Datsun was very clever using the same 6-cylinder engine/transmission and drivetrain platform from 1970 to 1983.
Not only did this make them easy to manufacture, but it lets an enthusiast mix parts from different years to create the perfect first generation Z. The secret is that the heavier 280ZX used physically identical 6-cylinder engines and transmissions from '79 all the way through 1983, making them simple bolt-ins into earlier Z models. Since a great many 280Z's and ZX's are in junkyards, what better time to breathe some life back into your car? So here is my formula for a very quick and fun 1970-78 Z, along with tested performance tips. 240-260 folks would want to swap everything, while 280Z and ZX people should keep their injection and ignition and change the drivetrain parts only.

FIRST - the car

Unlike Chevy Chevelles of which several million were made, there were only 360,000 or so 1970-78 Zs made. After 30 years how many are still running? Sadly, rust, wrecks, and rebuilds have sidelined most of them over the decades. Despite the nostalgia I don't see a problem removing the old engine and drivetrain and replacing them with newer versions. Without your intervention the car would likely never see the street again.....it's your car after all.

If you want to find a base model to use for your fantasy racer, try to find one of the first 12,000 or so 240Zs made from 1970 to early 1971. These are identified by a "240Z" badge behind the side window and two grills on the rear hatch. These '70-71s were the lightest of all ZCARs, at about 2300 lbs, making them the best for performance buildups. Later models went to a round Z badge behind the side window and removed the hatch grills. Unfortunately the weight went up a few hundred pounds too.

1970 240Z F54 with shaved P90, Nissan T5 5-speed, 4:11 differential

SECOND - the engine

Datsun made several blocks over the years, varying in bore and casting methods. Compared to the 240Z L24, the 260Z L26 had a longer stroke, while the 280Z L28 had both a longer stroke and  a larger bore. The way to identify the block is to look on the driver side of the engine, to the right of the motor mount. That's where they cast the block number.

Except for the turbo guys it seems that only since the late 1990s have have people focused on the F54 engines. Because of the Z's longevity these motors didn't show up in junkyards until then, well past the heyday of Z racing fever in the late '70s and early '80s. What people didn't realize is that minus power steering, AC, and other ZX plumbing the F54 was Nissan's final evolution as the most powerful and refined of the L-series engines...it had to be to carry the heavier ZX. Personally, I like the idea of putting a late model F54 engine in a first generation Z and converting it back to carbs. Very retro, but totally functional and quick.

So I suggest using the last of the L28's: the 1981-1983 F54. It's cylinders are "siamesed" meaning that instead of coolant flowing between all the cylinders as on earlier models they are connected between 1-2, 3-4, 5-6 with cast webbing for more rigidity. In addition, all There really isn't a "turbo block", all Datsun did to make the F54 a turbo motor was to replace the flattop pistons with dished ones to lower compression and add a turbo head with better exhaust ports.

It can be tricky determining exactly what's in a car as many have had the heads swapped over the years. First check the block code, and then the head code between the 1st and 2nd spark plugs. Check out the head page to see which head came with which block. Sometimes you have to do a little detective work to figure out what you have.

L28 COMMENTS:

• PISTONS The F54 motors with P79 heads ('81-83) have flat-top aluminum pistons. All other L28 motors (N42,N47,P90, P90a) came with dished pistons. In a performance engine, flattop pistons create a higher-quench mixture and allow for higher performance combustion chambers. Dished pistons are usually used to lower emissions.
  
  
• HEADS The P79, P90 and P90a heads are the three heads found on F54 blocks and all have the same chamber volume (53.5cc).  The P79 has diamond-shaped exhaust ports with steel liners that heat red-hot to reduce emissions, some say they reduce flow but I pulled a 13.9 1/4 mile with my carbureted P79, so it can't flow too badly. The P90 and P90a had square exhaust ports identical to L24 and L26 heads, my guru racer buddy says Nissan finally "got it right" on the P90 and feels it's the best flowing head out there. I have to agree, I just modified one and it's design incorporates the best features of all the heads: square exhaust ports, high-quench chambers, and steel seats. Check out my P90 and P79 pages for more modification details.
   
• HORSEPOWER A lot of factors affect horsepower and it's best not to fixate on numbers. But as a baseline the 1975-80 motors put out about 135 net, the 1981-83 motors 145 net. The little plate on the shock tower in the 75-78 280Z's engine compartment says 170hp SAE which is a sneaky way of saying 135 net.

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THIRD - carburetion

The optimum air/fuel ratio for car engines is around 14.7:1. Either the mixture and intake flow is correct for the engine demands, or it isn't... one of the most common mistakes on any high-performance motor is to over-carburete. More gas doesn't always equal more power.

Luckily the stock 240Z Hitachi SU is a great carb for both street and performance, and automatically meters the gas depending on the airflow through it. So whether you are stock or have a cam with large duration, with the proper needle the SU carb tries to keep the correct mixture from idle to redline. A simple, accurate design.

The "good" SU's were from 1969-1972 and will have 4 or 3 screws holding down the domed piston depending on which year it was made. The year makes no difference for performance, as the nozzles and needles from different years interchange. If you have carbs with the square choke flap in the inlet or flat tops then you have porly performing emission carbs. Exchange them for earlier SU models. A buddy of mine has a Mikuni 6-pak which runs great flat out, but he has had to spent a lot of time tuning them, very finicky. So for street performance and autocrossing I would stick with SUs.

FUEL PUMP
If you are using carburetors you can remove the stock mechanical fuel pump from the head to reduce drag from the cam and replace it with an electric pump. There are two types of aftermarket fuel pumps: Rotary Vane, and Oscillating.
The square Purolator/Facet brand electric pumps found in auto stores are the oscillating type. Reliable I'm told, but the design is very noisy with a loud tapping that's audible through the rear deck, especially if you have a quiet exhaust. A rotary vane pump produces a quieter whirring sound and is the style used on newer cars.

My own choice is the Carter CRT-P4070. It can produce 72 gallons per hour and 6psi max and is considered very reliable. Pushing fuel through my stock 240Z fuel rail it produces a steady 4.5psi at my SUs. The perfect spot for it is just under the mustache bar against the brace that holds the differential. I put a clear fuel filter on its inlet to protect it's motor.

A 240/260 carb intake will bolt right up to any L28 head. The bolt size is 8mmx1.25.

• The 1970-73 used the E88. I've heard of another (E36?) but never seen it.
• The 1974 260Z used the N36. This intake manifold is rumored to produce 10hp more than the 240 one. If it's true, simply bolting it on a stock motor probably wouldn't do much. A modified motor that needs more flow would benefit more: if it's true.

The manifolds are actually 2-piece: left and right, with a water line connecting them. However, I don't see any performance reason for removing the water lines, as they keep the intake temperature stable. Sitting over the exhaust and connected to the head they can get pretty hot. Vapor lock anyone?

INTAKE MANIFOLD BALANCE TUBE
The balance tube between the intake manifolds performs the simple task of creating a spot for the brake booster hose, vacuum hoses, and PVC hoses to vent to. I'm not sure why people think blocking it off from the manifold will somehow increase horsepower, all that does is ruin the brake vacuum. Additionally, you want the PCV hoses to vent into the balance tube to keep crankcase by-products and blowby from dirtying up the block. Make sure the gasket under each end is sealed tight as a drum as they get squashed after 30 years and can leak air into the manifolds. Permatex makes a great roll of gasket material you can use to make cut your own.

This little vent on the front 70-72 SU carb photo above is a real enigma. Some people use it as vacuum tap to connect to their distributor vacuum advance, which is incorrect. If you look inside the carb the size of this port is less than the diameter of a pin....there's no way this tiny hole could pull enough air to operate a vacuum dashpot (suck on a hose connected to it if you don't believe me). Z Therapy says it's a choke air vent which operates when the butterfly is cracked open on startup, I believe their version. While I don't think it provides any benefit on my car I didn't want to cut it off or seal it up, so I have a rubber cap on it.

NOZZLES AND CARB NEEDLES

• the '70-71 240 used "N27" needles and related nozzles.
• the '72 manual trans car used N54 needles, the '72 automatic used N58, both with the same '72 nozzles.
• the '73 nozzles/needles were emissions designs, not recommended for performance.
• SM needles from British SU's are excellent for performance. 

My own setup is 1970-'71 nozzles, SM needles on a set of 1970-'72 carbs, 260Z "N36" intake.

• Always mount an electric pump as close to the gas tank as you can. It's better to "push" the gas rather than "pull".
• Remove the little copper mesh filters in the SU float bowl inlets. These can restrict flow. I have a Purolator "clear" fuel filter installed where the hose comes off the firewall. This is easy to inspect and clean.
• Retain the water cooling through the intake manifold.
• Don't block off the PCV hoses. It's important that the crankcase be vented to the intake so the motor stays clean. Using a little K&N breather on the valve cover is fine on a good motor, but can stink the car up with fumes if you have ring blowby.
• On 240s, keep the "flow-valve" on the driver fender-well connected. This pulls fumes from the gas tank and burns them in the carbs.

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FOURTH - the transmission

Borg T5 and lightened 240mm turbo flywheel

Datsun used three 5-speeds for U.S. Zcars

• One from '77-80
• One from '81 to 83.
• A Borg-Warner T5 in 1983
  
  My page on installing a Borg-Warner T5 in a 1st generation Z.

Nissan called the '77-80 trans a "wide ratio" while the '81-83 was called a "close ratio" 5-speed. The early one has the lowest 1st/2nd gears for acceleration, but a wide spread between 2nd and 3rd. The later one has a taller 1st/2nd but a tighter spread between 2nd and 3rd. It also has a much taller 5th for cruising. Your choice.

According to a Z Doc friend who rebuilds transmissions the early 5-speed is a 4-speed with 5th and reverse sharing the same fork. He said it's common for people to "blow" 5th gear as the fork is weaker. He stated the later 5-speed is a genuine 5-speed which is stouter. I call the early one a 280a and the later a 280b to keep them straight. 

Keeping the speedometer correct
Everyone gets confused about how to calibrate the speedometer after swapping differentials, it's actually very easy. The speedometer is metered by a plastic, toothed cog on the end of the speedometer cable that screws into the transmission. This cog is paired with the differential, not the trans. So it doesn't matter which trans you have, all you do is select the proper cog for the rear-end ratio you have in the car. While they are colored for easy identification, the Nissan dealer only has them in their part list as "17, 18, 19, 20, or 21" tooth cogs. Here's how to figure out which is which.  

NOTE: There are 2 different aluminum cog sleeves, a '75-80, and '81-83. These have different cog "offsets". If you look closely in the picture above, notice how the red cog is offset to the right, and the blue to the left. This means you must keep the sleeve with the trans it came in, and only swap the cog. Otherwise the cog may not mesh the proper way inside the trans. The weird one is the larger red 4.11 cog, which requires a later ZX sleeve to fit into the older '77-'80 trans (I tried it). But will it fit into a later 280b? I don't believe so, the red cog is much larger than the white. So I'm using a white cog on my 4.11 rear.

• On 240's, you will have to cutout about 2 inches of metal from the front/right edge where the shifter goes through the trans tunnel when using a 5-speed. Otherwise the throw into 5th gear will hit. This cutting is the price of a 5-speed trans and is not a big deal at all, the console covers it.

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FIFTH - the flywheel and clutch

This is a 2+2 flywheel and clutch.

Measure the width of your flywheel's shiny clutch contact surface.

• If it's 225mm wide then you have a coupe version which uses a 550lb pressure-plate.
• If it's 240mm wide then you have a 2+2/turbo version with a 780lb plate and a wider disc.

Flywheels are identical in diameter and weight at 23 lbs (only the contact area is wider). But a turbo pressure plate and disc clutch are heavier than the coupe version by a few pounds. So how much performance is actually lost with a heavier turbo clutch assembly? Truthfully the only time you really need a stronger clutch is if your engine torque overpowers the clutch and causes it to slip. I agree it sounds neat to say your car has a "competition clutch", but it doesn't make the car faster.

Perfection Clutch (ZOOM) is my choice if you want a hot clutch. Not only are they one of the largest and oldest clutch companies in the US (circa 1919) , but they make 4 performance clutches from kevlar street, all the way through radical track. Amazingly they make all four of these clutches for 1970-83 Zcars. The also include a pilot tool, bearing collar and pilot bearing...a nice touch. Perfection makes stock replacement clutches too that include all the parts mentioned above for about $100. They openly state their stock clutches are made in China from German steel but advertise very tight quality control.

If you're on a budget you can get away with their stock replacement clutch, especially if you have a 2300lb 240Z. I have the stock one installed on my modified L28 with no problems at all. On a heavier 280ZX I would start with a Stage1 kevlar. Look for them through Summit Racing.

Zoom Stage 1, 2, 3, 4

LIGHTENED FLYWHEELS
Light flywheels have been used for decades in racing to reduce drag on the engine and to make it spin up faster. It won't make the engine develop any more horsepower internally but can cut down on parasitic drag and give you that Indy-car revving sound. Better for track racing than dragracing as on smaller engines the rotational inertia that helps the car off the line is reduced. This loss of inertia can make it harder to modulate off the line, some people consider the the lightest ones (about 10lbs) more difficult to drive on the street because the engine can stall more easily when cold. On motorcycles, having a too-light flywheel can make it stall between shifts(!) On my L28 I am using a stock coupe flywheel lightened to about 16 lbs. It speeds up my revving by about 20%, and makes the car much snappier without losing drivability.

CONVERSION NOTES

•  There are 2 versions of flywheels on all '75-83 motors: coupe and 2+2/turbo. 23 lbs each.
• Coupe and 2+2 clutches aren't interchangeable because the pressureplate dowel holes won't match the flywheel dowels.
• A Zcar 5-speed will fit on any year Z block and any year L28 clutch can be used, but the throwout bearing "collar" must match the style of the flywheel (coupe or 2+2). In other words, if you have a 2+2 flywheel, you need to change the throwout collar to a 2+2 version when using a coupe trans. And vice-versa.
• Auto transmission engines have a 1/4" metal spacer between the driveplate and crankshaft, remove this when adding a flywheel.
• A pilot bushing needs to be installed in the crankshaft if using an auto trans engine (they didn't get one).
• Unless you need the accessories don't use a big 3-row harmonic balancer, get rid of it. I've read that taking 10lbs off a 10" rear flywheel is the equivalent of taking 207lb off the front of the car. So I believe removing 5lbs from the front of the crankshaft is desirable. Also, I've been told the 3-rows like to break up over 6,000rpm. 
• All L28 balancers have identical TDC timing marks and are interchangeable.

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SIXTH - the differentials

4.11 from 200SX turbo, freshly painted.

There were three different Zcar R-200 ratios from 1975-83, none were limited slip until 1987. 280ZX automatic transmission cars came with an R180, so if you want to find a 3.90 look for a 1981-83 5-speed in the junkyard. Don't try to analyze the confusing table in the Haynes manual, this is the easy way to do it: 

If you want performance get the R200 out of a junkyard '81-83 5-speed, NON-turbo ZX (3.90). if you're speed freak like me use the 4.11 out of the 200SX turbo. The '85-86 200SX turbos came with a R200 while the non-turbo models I've seen have a solid rear axle. While not LSD differentials the 4.11 adds more snap over the 3.90 and can make your Z a real rocket off the line. It came with CV halfshafts which aren't needed, just use regular Zcar R200 halfshafts on a 4:11 in a first generation Z.

1975 NOTE: 1975 R200s and driveshafts came with unique rear driveshaft/differential flanges. So if you plan on doing a later year R200 swap into your 1975 280Z, you should try to find a 1976-78 R200 driveshaft to use.

BTW: to get R200 halfshafts out, DON"T pry them out and damage the flange or spend an hour unbolting the differential-side. Simply unbolt the wheel end, and "yank" the halfshaft hard a few times. A little circlip in the diff holds it but it will pop right out, the yanks don't hurt it. To get them back in you can lock it in place by thumping the end with a mallet till it locks.

LIMITED SLIP DIFFERENTIALS
Despite the performance of the Z, Nissan only made a limited slip diff very late in the Z's life. They made 2 types: a standard LSD, and a LSD with a viscous internal drive. The 1987-89 Turbo 300ZX's had the "good" 3.70 LSD, and can be identified by it's finned rear cover. This cover needs to be replaced with the smooth R200 cover to fit properly to the 280Z mustache bar, and the front driveshaft flange on the diff. needs to be replaced with the one your driveshaft uses. The '88 white SE 300ZX came with the "viscous-drive" R200, and can be identified by a sticker on the driver-side of the diff that says "VISCOUS LSD". While the viscous model fits into an earlier Z, R200 halfshafts don't lock into them without some fabrication of new halfshaft fittings.

TO DETERMINE THE RATIO (internally)
If you're not sure which ratio R200 you have lying around the garage, check it this way: Remove the rear plate (drain the oil of course). Then rotate the large ring gear until you see these numbers stamped into the edge facing you.

• If it's a 3.54 it will read  "39:11"
• If it's a 3.70 it will read  "37:10"
• If it's a 3.90 it will read  "39:10"
• If it's a 4.11 it will read  "37:9"

The first number marks the number of teeth on the large ring gear, the smaller is the number of teeth on the pinion gear connected to the driveshaft. Someone suggested swapping ring and pinions around to create the ratio of your choice. I checked with my buddy the Z Doc, and he said it's very difficult to get the preload and tooth geometry setup properly (he tried it). Oh well.

HOWEVER: Since the 3.70 and 3.90 apparently use the same 10 tooth pinion, I wonder if a 3.90 ring could be swapped onto a factory limited-slip assembly? This would make a "factory" 3.90 limited slip!

GEAR OIL REFILLING TIP: Instead of uninstalling the differential I remove one halfshaft and add the oil though the side of the case. Easy

SEVENTH- Ignition

There is more to the Zcar ignition system than any other part of the car, so this is a long section below.

POINTS vs ELECTRONIC IGNITION

Points distributors are an obsolete technology when it comes to high performance engines. The reason is that Dwell (the amount of time the points stay open) changes if there is even a tiny bit of play in the distributor shaft. Dwell directly affects ignition timing, so any slight rocking back and forth of the shaft puts your ignition timing all over the place...not good on any motor.

Electronic distributors are usually rock-solid when it comes to timing. Shaft play can still cause slop in the distributor, but generally doesn't cause the timing to fluctuate the same way.

Nissan made two ZCAR distributor IC modules from 1979-'83

WIRING A 280ZX DISTRIBUTOR INTO A 240Z

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This mod converts a 240Z to an ZX electronic distributor. It's not needed on a 280Z or ZX which already have electronic ignitions.

• Find a 1979-1983 280ZX distributor. Any year '79-83 can be used, but if it's '81-83 it will have the E12-92 module which needs to be changed to a E12-80.
• Remove and clean the metal rear of the IC module so it can ground itself to the side of the distributor.
• Remove the triangular hold-down plate on the base of the distributor. Burnish it, as well as the spot where it contacts the distributor and replace...this helps everything ground well to the block. Note that the hold-down plate rotates, you may need to play with the position to get the proper timing mark range you want.
• Use quality spade lugs and wire with TIGHT crimps, and solder the wire to the spade connections if possible. Don't solder or crimp onto the E12-80, just make sure the spades fit on tight.
• You will need to buy a L28 distributor base for the front cover if this is a 240Z. Motorsport Auto used to carry them them.
• A 240 tach will not work with this setup because its inductive pickup that isn't compatible with the signal from the E12-80. There are two solutions: Replace it with a 75-78 280Z tach and connect the tach sensor lug to the - terminal on the E12-80 module. If the tach jumps around, solder a 7500-10,000 ohm resistor inline with the sensor wire to reduce the signal voltage. If it still won't work buy a Autometer #3990 black face tach.
• WARNING: if you have a MSD or Crane, DON'T hookup the E12-80 or tach directly to the coil. The 450 volts can fry it. Follow the ignition's hookup guide.

ALTERNATOR UPGRADE
Old news, but the teeny 40 ampere alternator and mechanical voltage regulator that came in the 240Z are marginal, especially when using an electronic ignition system. If you're not an electrical guru here's the basic explanation:

CURRENT is the amount of voltage 'draw' that your electrical system pulls from the battery or alternator. Every electrical item from your gauges, to dashlights, to the ignition, draws this current rated in amperes (amps). The manufacturer simply adds up the total amperage that electrical items in the car use and installs an alternator with enough current to supply everything. If everything in the car draws 30 amps when used, you would likely get a 40 amp alternator.

In the early 1970's a stock 240Z only needed an AM radio, points ignition, basic lights and was given a tiny 40 amp alternator. But today you add an MSD type ignition, a big car stereo amp and flamethrower headlights, and you easily pull several times as much current as the stock alternator can supply. In addition the Voltage Regulator on the firewall is a "mechanical" type with points inside that open and close just like on an old distributor. These mechanical regulators have been obsolete for 30 years, even Nissan went to internally regulated alternators in the late 1970s.

I realized I needed an upgrade on my 240 when I noticed my ammeter needle would jitter at idle. Even more obvious was that at night my dash lights would dim when I neared redline. After spending hours checking grounds and cleaning connectors, I finally decided to get rid of my vintage setup. Instead of a monster aftermarket alternator that puts out 120 amps, I took the factory route and used a Nissan 1981-'83 non turbo 280ZX which was 60 amp version, the turbo with a 70 amp. I haven't tried the turbo version but the non-turbo version swaps right over.

THE ALTERNATOR MOD FOR 240Zs only:
Buy a new "1981-83 Nissan 280ZX non-turbo" alternator at the auto store. Replace the original alternator and follow the directions below. Before you start, fabricate two little wire "jumpers" (cut a wire about 3 inches long, strip the ends, and solder/crimp a male spade on each end.

• Unplug and remove the voltage regulator on the right firewall.
• On the regulator's rectangular connector coming from the wiring harness, look at the wires going into the bottom. Plug in a jumper to bridge the white wire and the yellow wire. It may appear that both wires are yellow (due to age). Luckily there are only two solid light-colored wires...these will be the white and yellow.
• Plug the 2nd jumper between the black w/ white stripe, and the white w/ black stripe wire. Leave the other holes alone.
• Reconnect the thick white/red stripe wire (Battery) to its spot on the alternator.
• Reconnect the thick black wire (ground) to its spot (Earth) on the alternator.
• The "P" connector on the new alternator isn't used.
  
  
• IMPORTANT STEP: Go to Radio Shack and get a "1N5402" diode. This needs to be soldered inline with one of the wires on the plastic T connector that goes to the back of the alternator. If this step is missed, the engine won't turn off with the key(!) Make sure the "line" on the end of the diode faces the connector. Don't solder directly to the connector like my graphic shows...just solder it inline with that wire of course. Diodes are sensitive to heat so be careful not to overheat the leads when soldering.

COMMENTS: On startup I found my exhaust note is smoother at idle and idle is rock solid. I suspect the more stable voltage at idle enhances the MSD ignition. On the road the engine feels smoother with none of the hiccups I was getting when lugging the engine to low revs or accelerating in too low a gear. Revving past redline is more smooth and solid with a bulletproof feel. My ammeter is solid and accurate and my dash lights are brighter and wipers are faster. I measured 14.58 volts at the battery...just what it should be. I'm not saying this makes the car faster, but it's more driveable now without the voltage sagging at idle and redline like before. This is probably the easiest and most worthwhile of all the 240Z mods. I would save your old 240 alternator/regulator for an emergency, or to swap back to stock someday.

NOTE: You may need to come up with a way to shield the connector and jumpers from the elements. You could clip the connector from the old regulator to make a plug-in jumper arrangement which would look cleaner than just using two jumpers.

AFTERMARKET IGNITIONS
There are several companies battling out on who has the best ignition. Most use the same concept: provide a multiple spark out to 3,000 and then revert to a single hot spark. So the brand choice is up to you. I have used both a Crane Hi-6 and a MSD 6A on my carbureted F54 fired by a E12-80 on a ZX distributor, both felt similar to me. The Crane has a more advanced RISC processor, while the MSD has better credentials, your choice.

PERTRONIX
I haven't used one but a friend has one on his '71. It seems to work perfectly and I'm impressed at it's simplicity and quality. A great option if you can't locate a L28 electronic distributor. I would still pair it with a MSD ignition to boost the spark though.Make sure to lube up your breaker plate and check the operation of the vacuum advance dashpot.

CHEVY HEI MOD
Using a GM HEI module is a 25 year old way to put a 1975-78 280Z distributor on a 240. The problem is that the GM HEI was designed for the low redline of a V8 and is well-known for it's spark and poor saturation abilities above 4,500rpm, even Chevy people hate them.

I've heard of people adding a HEI chip onto their 280Z or ZX ignition which makes no sense: The E12-80 is a superior ignition module, why would you add a HEI chip to make a "double-ignition"? So while the HEI "works" for average driving, it's a cheap mod and I don't recommend it. The HEI modules sold in the auto store sells for $14 the Nissan E12-80 for $200, you be the judge. Use the Pertronix if you want to save money.

PERFORMANCE
I spent some time on the interstate with a stopwatch doing 60-80 and 70-90 runs in the top three gears, comparing a E12-80 firing a MSD 6A, and a E12-80 module by itself. The times were within a tick of each other, back and forth. Kind of inconclusive. The MSD/Crane DO give smoother idle, need little choke, drive better when cold, and cut down on my exhaust smell at idle. But despite all these credentials, I'm not convinced they actually makes the car faster over a E12-80 alone. I've decided that on a carbureted motor, the better starting and idle quality alone are worth using a MSD-style ignition, even if I'm not sure the top end is better.

COIL TYPES 
There are two basic coil types: oil-filled "can" and "square"' transformer style (like the Crane PS-91). But I wouldn't get hung up over which is better. The specs are what you should focus on.

• A coil is simply a transformer that steps up 12 volts to several thousand. Its positive terminal gets a constant 12 volts to power it on, and a pulse to the negative terminal causes the windings to produce a large spark out of the center tower. This is the common setup on just about every car over the last 100 years. A capacitive discharge ignition like a Crane or MSD sends 450 volts to the coil (instead of 12). This is why a better ignition produces such a mammoth spark out of the coil.
  
• Serious racing coils have very low resistance "primaries" (primary windings) which draw a large amount of current. This is why real racing coils are advertised to only run with a companion racing ignition: if you run one on a stock ignition the coil can draw too much current from the ignition and damage it..
  
• There are many performance coils out there but some designs haven't kept pace with technology. Look in the Summit Racing catalog and you see several generic oil-filled "performance" coils. I consider these iffy as they were designed for stock engines or muscle cars with points, not 10,000 rpm racing ignitions. I doubt they have changed internally since the 1970-'80s.
  
• MSD and Crane make coils designed for high performance. I have used the MSD Blaster-2 (.73 ohms), Crane PS-91(.43) and PS-92 (.20). I really like the Crane's E-coil design and when I accidentally cranked the engine with the coil wire off, the end of the PS-92 was covered with crackling blue fire. This coil was HOT! My PS-92 mysteriously went dead after a few months though, I heard the same experience from someone else too. So I'm using a Blaster-2 again.
  

TACHOMETER
I would recommend getting rid of your old 240Z tach. Vintage, but not designed well, they're inaccurate and start jumping around as they age. They're not as accurate at redline as you would think even when working well. I'm not into the white face look, I replaced mine with an Autometer #3990.

BALLAST RESISTORS  
Surprisingly, stock coils on older 12V points systems on cars were designed to operate with a max of 6-8 volts. The reason is that on points distributors the entire voltage from the coil passes through the points, and too much voltage would burn them out. So the ballast resistor was put inline with the 12+ wire to the coil to limit the voltage the coil produces.

When you turn the key to start, the ballast is bypassed, and the coil gets a full 12V to put out a hotter spark for starting. Releasing the key inserts the resistor back into the circuit to preserve the life of the points. Why not design the ignition to use 12V all the time? Well, nowadays they do but before 1977 or so that's the way points ignitions were designed. This means if you buy a high performance coil and simply install it, the ballast resistor may limit the new coil's power output. On a points distributor you can connect a wire across the ballast, it will route a full 12-14v to the coil and pick up some voltage, but it can shorten the life of the points.

SPARKPLUGS  
NKG plugs are the best I've used in a Z engine ~ smooth, predictable and long lasting. Bosch plugs are fine on German ignitions but not on Z motors. I've been told that German ignitions evolved with a different overall resistance from coil to plug than Japanese ones. For whatever reason, many Z owners report misfiring and poor performance from Bosch. There's a big markup on "platinum" plugs too...companies know that people think products with "gold, platinum, silver, diamond" in the name are better. Centuries-old marketing.

I think the best Z plug to use is the NKG BPR6ES-11. A few years ago Grassroot Motorsport magazine recommended the NGK ZFR6F-11 sparkplug for stock Z engines. It's a "V-Power" plug with a projected tip which extends out into the center of the chamber which simulates advancing the timing slightly by firing the mixture faster. Projected tips provide a more complete burn through the rev range, creating "free horsepower" and improving throttle response. Be careful using extended tip plugs in a shaved head or you might touch the piston(!)

Also, be wary using multi-electrode plugs, especially on high compression motors. I spoke to a NGK tech once, who said that the nooks and crannies on multi plugs can create lots of little hotspots and contribute to pinging. He said that multis are mainly designed for the modern hemi-style chambers on Hondas where the mixture is quenched in from all directions.

My 2 CENTS: Don't waste your time on Splitfires or plugs that use hocus-pocus: use the plugs the factory chose. If you want to increase spark performance spend your money on upgrading the ignition system instead.

PLUG GAP TIP
Drag Racing lore is when using a high performance ignition/coil to open the plug gap to .050 (or wider). This is said to create a larger, longer duration spark to increase power. But on high compression motors today's wisdom is to keep it at .045, because as compression goes up, it's harder for the spark kernel to start. Crane says to use .045 for "offroad and high-performance usage", MSD says .050. NOTE: if you open it up to .050 on a stock ignition/coil you will only weaken the spark. I played around on mine and I like ".050 with my MSD 6A.

PLUG WIRES
I really like 8mm Magnecor competition wires. Very high quality blue silicone, they are "real" competition wires and put the other designs I've seen to shame. Grassroots Motorsports Magazine did a test a while back and found that these wires added 1.5hp to a stock BMW motor(!) But despite what people think, performance wires don't actually "increase" horsepower. They simply work transparently to allow the coil's full output to reach the plugs consistently. These certainly do, with very clean output all the way past redline, they even smoothed out my idle. Nice. Don't use the do-it-yourself Accel yellow performance wires. I've tried sets on different cars since 1980 and they tend to corrode inside the cores.

MECHANICAL  ADVANCE CURVE
There appear to have been two different distributor choices on '81-83 L28s. If you take off the breaker plate you can see "8.5" or "9" stamped into the top of the advance weights. 8.5 came on the manual transmission cars, 9 came on the automatic cars. Double these to get the total mechanical advance for the distributor (17 or 18 degrees). Published specs show the mechanical advance coming in fully at 2800pm on the 8.5 degree and 2700 on the 9 degree models. The vacuum advance is listed as adding 15 degrees. This means that a stock '81-83 distributor gives you 17-18 mechanical with 15 degrees vacuum on top of that.

A mistake people make is bumping the idle timing way up to push the maximum closer to 34-36 degrees which is considered the region for performance. This results in pinging and can damage the engine. What you want done is to find a hot-rod shop that recurves distributors. They can alter the weights and springs inside to widen the advance range so you have the correct timing at idle but when revved the maximum advance is bumped way up to the mid 30's. Sorry, there is no perfect curve though, engine compression, head work, etc all change the curve. It's best to let the shop determine what's best for you.

VACUUM ADVANCE
For the vacuum advance dashpot to work properly it needs to be connected to a "manifold vacuum" inlet as opposed to a "port vacuum" type. Manifold vacuum is what the brake booster uses...this is the intake area between the carb butterflies and intake valves. Port vacuum is "outside" the intake manifold and is usually in the outer throat of one of the carbs. Port vacuum is very old fashioned...Manifold vacuum is what these engines use.

The vacuum advance dashpot's purpose is to react to vacuum from the intake manifold to move the breaker plate inside the distributor to keep the timing "optimum". It adds its advance on top of the amount the mechanical advance produces. Unfortunately, after 25 years, many dashpots are leaking, causing no advance and a big vacuum leak into the intake manifold. Test yours by sucking hard on the hose going into the dashpot. With the distributor cap off watch the vacuum arm pull in. If you "hold" the pressure, the arm should stay fully retracted. If it slowly leaks down, it's internal diaphragm is leaking...and it should be replaced (it can't be fixed). If you hear your breath hissing then you have been leaking air back into the intake manifold which is not good. To fix the leak temporarily plug the dashpot hose going INTO the manifold. It's better to run without vacuum advance than to lean out the motor and burn a valve. You can still buy dashpots from the dealer I believe.

Removing the hose from the dashpot and plugging it is how you disable vacuum advance and convert the distributor to run only mechanical advance. Not running vacuum advance can make part throttle acceleration a bit sluggish and supposedly hurts gas mileage. Vacuum advance doesn't work under full-throttle so if you only drag-race vacuum advance isn't needed.

DIELECTRIC GREASE
Dielectric (d-lktrk) noun.
A nonconductor of electricity, especially a substance with electrical conductivity of less than a millionth (10-6) of a siemens.
Dielectric grease does not conduct electricity. It's purpose is to protect the surfaces of metal conductors from corrosion, sealing spark plug boots to keep water from getting in, as well as preventing arcing. Putting it on metal connections like distributor cap terminals, rotor tips, or injector contacts will block signal transfer. Personally I think the companies deliberately call it "Tune-up grease" so people will slather it on at tune-up time thinking it's some sort of metal cleaner.

To clean old connectors I like to use an exacto knife to scrape any oxidation off. Then use a quality contact cleaner/solvent to blast them clean. Standard brake cleaner spray is fine, but on electrical connections you want to leave a thin film of protectant on the metal to keep it from re-oxidizing. Years ago the high-end magazine "AUDIO" recommended WD40 for cleaning the volume controls on high-end preamps. Places to clean are the voltage regulator connections, wiper motor plug, injection brain connector and injectors. Also open the injection airbox and spray the circuit board to clean the resistive wiper. Also check the little ground connector that screws into the lower shock tower just below the battery on 240s.

 MY OWN SETTINGS?
I use a 1981-83 manual-trans 8.5 (17) degree distributor, with the earlier E12-80 module on the side to fire my MSD 6A. I advance my distributor timing about 4 degrees to 12btdc. After lots of swaps and testing I believe this is the best setup for a L28 with flattop pistons.

This is why a short duration cam can't produce power at high revs, the valves aren't open long enough.

I've used a two dual duration cams (Crane 262/272 and 272/282) with good torque. My current cam is a 268/268 duration (230/230@.050") which is also had good torque. Your choice.

CAM BRANDS
Crane cams used to make some great L-series performance cams. They were unique in that the lobe base-circle dimensions were identical to the stock cam. And with .450 lift they were simple drop-ins that could use stock lash pads and springs. All you needed were new rocker arms...perfect. In 1996 I bought a 262/272 duration cam (#168-0010) directly from Crane for $118. But by 2003 they decided Z cams were "special grinds" and the prices went up to $300ea. Finally, in May 2005, Crane told me via email that they can no longer obtain the blank steel cam billets from Nissan, so they are dropping ZCAR cams from their catalog after many years of production.

All other cams on the market (Schneider, Comp Cams, Isky) are quality remachined (reground) from stock cams with smaller lobes that require thicker lash pads. These are considered excellent cams and running thicker lash pads is OK, but they add extra weight to the valvetrain and are headache to measure and purchase. And after adding up the price of new retainers, lashpads, springs, labor and downtime, I like to use a plain old drop-in cam.

CWC BILLETS
Stock factory Datsun cams are stamped "Japan" and are made of some very tough metal, lasting 200,000+ miles with no problems. But blank Datsun cam billet have been unavailable in the Nissan Motorsports catalog for over 7 years and also show as unavailable on the Courtesy Nissan site. So as far as I know no one makes new Zcar cam billets anymore except the company "CWC". I Googled CWC on the internet and CWC Textron out of Michigan is listed as the "industry leader in ductile iron cams for passenger car and light truck applications".

Interestingly, my friend the Z Doc in VA. said he had noticed that aftermarket ZCAR cams with a "CWC" marking were prone to lobe failure when used with performance springs. I took a look and both my failed Cranes were stamped "CWC", which seems to bear this out. So I suspect that Crane really dropped their Datsun cam line due to too many complaints of cam failure. Since Crane appears to have been using CWC for years, their argument that they suddenly can't get the Nissan billets doesn't hold water.

However, I suspect low ZDDP in motor oil is a chief cause of cam failure. Since CWC is the only new cam billet choice out there the trick is maximizing its longevity.

ONE SOLUTION:
Webcamshafts of Riverside, California caught my eye. They have 45 years experience with creating custom and antique engine grinds as well as a couple of decades of producing Zcar cams. And after talking to them on phone they appear to really know their stuff. It turns out they use CWC billets for their Z cams, but they "Nitride" them which involves heating them to 900 degrees and in an ammonia gas chamber. Nitriding creates a super hard lobe surface and is considered to increase the life of a cam 10-fold (no kidding).

Unlike V8s, you really don't need a radical cam to wake up a Z motor. So I resisted the temptation to go with their stage 2 cam the "# 91" which has 238/238@.050 duration. I was worried it would lose too much bottom end torque on the street. So after some discussion, I decided instead to order their "# 94a" grind which has .430 lift, 230/230@.050" duration which they said uses stock base circles(!) It has an advertised duration of 248 which may look low, but it's the true 230 duration at .050" duration that really matters.

So later when I opened my mailbox I found a nitrided, higher duration, new CWC billet cam with wonder of wonders...stock base lobe circles! I installed it in my P90 head in mid October 2005 I found the wipe patterns on the rocker arms were perfect...this makes the 94a a true drop-in cam. NOTE: If you go with their #91 or higher grinds I'm not sure if they can retain the stock base circles. Talk with them before you buy to verify what you want.

PERFORMANCE: Despite its moderate specs on paper, the 94a isn't a baby cam. The exhaust note is deeper than stock with a nice cam burble which idles best about 1000rpm. On the road the big L28 torque bump between 2-3K is lessened slightly but it doesn't have that "dead below 3k" feeling of some higher duration cams. Acceleration is strong and linear down low and when you tach it out the acceleration is very strong and it pulls hard all the way to 6800rpm. It is a bit finicky in very cold temperatures, so you have to wait a couple of minutes for it to warm up.

VERDICT: The Webcamshafts 94a grind is an excellent all-around performance cam...the only one I know of using stock base-circles. It's great combination of driveability and performance. Recommended.

SPRINGS AND VALVE FLOAT
The redline on a 240Z is 7,000, the 280Z is 6,400. This has nothing to do with the springs however. The valve springs were identical from 1970-83 and a properly tuned 2.8 liter motor can easily rev above 7,000. Redline differences on motors are because the larger an engine's displacement, the lower the usable power range. V8s can be a low 5,000 while a motorcycle might be 12,000 or higher.

Valve float is when the valve spring can't control the valve at high revs and the valve flutters on the seat. This makes the engine misfire and lose power of course. It became an issue years ago when American V8 engines came with poor valve springs from the factory and would float the valves at ridiculously low revs. So drag racers started installing heavy valve springs to try and control the valvetrain at high revs. But I've never heard of or experienced valve float on any Z motor with stock springs, they were that good from the factory. However, if you are rebuilding a cylinder head, I would replace your 25 year old stock springs as it's a good time to do it.

ROCKER ARMS 
You've heard this before, but when replacing the cam you should always replace the rocker arms. Everyone always wants to save a couple of bucks here, but you CAN'T. Even though the arms' surfaces might look smooth, they all have a subtle wear pattern that's mated to it's respective lobe. This mating takes place in the first few minutes of new cam/engine startup, and creates a perfect meshing between the two. If you use old arms with a new cam, the subtle wear pattern in the pad surface will wear into the cam lobes and damage them. This probably the most misunderstood part on a Z motor.

ROCKER ARM BRANDS:
I broke in a new cam a few years ago using the now discontinued Crane Cams rocker arms. Several months later the engine started missing. On investigating, several of my cam lobe tips were actually worn down(!) They were broken in properly and I always used quality oil, so this was a shocker. In looking at the rockers, the metal on the pad surfaces was porous and veined, and looked like cast pot metal. A Crane tech told me one the phone that the porous metal was "normal' and that it was a specially chosen composition to work with the cams. ...hmmmm. I only got 5,000 miles out of them.

In comparing the other non-Nissan rocker arms, I noticed that the Sealed Power and Melling brand used the same cheap pad metal. Just speculating, but I suspect that Federal Mogul/Sealed Power wholesales their rocker arms to everyone, who repackage them under their own brand name. The real Nissan brand rocker arms are unique, lighter, ultra-high quality forged rocker arms with shiny steel pads...the reason why Nissan cams can pass 200k miles with no problems. Expensive, but worth it.

Motorsport Auto sells real Nissan arms for much less than Nissan or Beck Arnley. I installed a set and they broke in perfectly. Please keep em' in stock Motorsport........!! I also just broke in a new cam with reground rocker arms from Delta Cams of Washington. They have two methods: you can order pot luck rockers from them or send in your own to be refinished. Personally I sent in my own to be refinished...that way I know their history and that they were all matched. They grind off as little as possible and for about $50 is a genuine deal.

HISTORY
The quality of the oils used in the 1970's-80's was horrible compared to today. The old oils sludged up, burned, and turned to varnish over time. I remember a mechanic telling me he knew when a car used Quaker State oil by the amount of gunk in the bottom of the oil pan. That's why the "in-thing" back then was to change your oil every 2,500 miles, otherwise it dirtied up the motor.

Well, motor oils in the past 20 years have come a LONG way, even more in the past 5, because of the demands of turbos and exotic high-revving motors. The secret of oil quality has to do with the API rating. The first letter (S) means the oil is rated for a gasoline engine. The higher the second letter, the higher the levels of detergent, varnish inhibitors, viscosity improvers in the oil. The old ratings from the 1970's (SA, SB, SC, SD) are obsolete, while today the current ratings are SM. That's why today an engine with 50,000 miles will be nearly clean inside, while motors from the '70s have a brown film baked on everything.

So changing your oil every couple of months isn't as critical as it used to be. The filter catches the dirt the same as it's always done, but the oil maintains it's slipperiness (viscosity) for well beyond 5,000+ miles now. The oil change Lube shops are having problems as a result. They still tell people to change oil every 3,000, while new cars manufacturers are saying 5-10,000. Times change.

SYNTHETIC vs. PETROLEUM- The age old debate
You'll get no argument from me: Synthetics are the best out there and help lengthen the life of the cam lobes. However there are a couple of rules you need to follow:

• don't use a synthetic in an old motor that's always used petroleum oil, especially if it's high mileage and been abused/badly maintained. This is because synthetic is highly-detergent, and can liquefy the old engine sludge and can clog the oil pickup screen. In any case, switching to synthetic on a motor with 180k hard miles isn't going to show much improvement.
  
• despite what Chevy and Porsche do, don't break in a motor with a synthetic. Rings and cam lobes need a certain amount of friction to break-in properly, especially on rebuilds. Break it in with a petroleum oil, and change to a synthetic at 1,500 miles.
• don't combine brands of synthetic. Some use different "bases", and may not mix properly.

SINGLE WEIGHT
A single weight oil (ex: 30W) remains the same viscosity in all temperatures, while multis (ex: 10W-30) change with temperature. Singles are identical in quality (SL/SM rated) to multi-weights, but people tend to overlook them in the store. They aren't good in low temperatures though because they thicken. Hence the creation of multi-viscosity oils.

Porsche used to recommend only single weight oils in their 911 engines into the 1970's, and Crane use to recommend only a "single-weight Pennsylvania crude" to break in their new cams. And engine lore especially on motorcycles is to use single weight to break in a motor. This creates constant friction at all temperatures for balanced break-in. I agree and use "Heavy Duty Castrol 30W" for break- in, until the rings seat at about 500 miles, then switch back to a multi or synthetic. My friend the Z Doc recommends using a straight 30W in the summer in the southern U.S., and changing to a 10W-30 in the winter.

MULTI WEIGHT
Despite what your old manual says, don't use 10W-40, no new engine today uses it. Instead, use 10W-30. Because it's lighter, it will free up a couple of horsepower, rev faster, and will reach all bearing surfaces more quickly. I wouldn't use 5W-30 or 0W-30, I think those are too thin for Z motors. At the same time, don't use 20W-50, that stuff is like molasses and is meant for older VW motors with large bearing clearances. 

OIL ADDITIVES
25 years ago when oils were crappy, using an additive was a pretty good idea. But today, SM grade oils are so superior they're not necessary. Have additive companies like STP even changed their formulation since 1980? I doubt it. The API rating is probably horrendous. But those companies keep cranking out cans of oil treatment like it's 1978 for some reason...I guess old men somewhere still buy the stuff.This STP FAQ sounds like it was written in 1963, notice there are no specs on the API rating.

MY CHOICES 
See the Oil section on my Rebuild Page for recommendations

OIL PUMPS
The 1981-83 Turbo 280ZX came with an oil pump that put out more pressure and volume than standard oil pumps. The automatic trans 280ZX turbo version has a higher CC volume per rotation than the manual trans pump. The reason is that the auto trans cars came with an oil cooler and needed the extra "ummph" to supply to it. So upgrade your L series motor to a turbo pump and pick up better lubrication, and get your oil needle off zero. Mine hovers at about 15 psi at idle and goes up to about 65 at speed. If you're lucky you can pick one up in the junkyard for next to nothing.

If you buy one new, be careful. The auto store might secretly list the same part # for stock and turbo pumps since they were physically interchangeable. I would buy a turbo pump from Victoria British or Motorsport Auto to guarantee you get a real one.

I originally used the individual "mesh-flo" basket types for my SUs. They looked great and seemed perfect. Unfortunately the clips kept getting loose and I eventually lost them on the interstate.

After losing the clips, I installed a 240Z air cleaner and cut the old filter foam and stretched it across each carb inlet with a zip tie holding it to drive to the store. Strangely, I found the foam was restrictive, and the engine wouldn't rev over 3500rpm. It appears the foam in these "performance" filters is actually pretty marginal in it's flow capacity when stretched. It addition, they draw in the hot air from the exhaust manifold which isn't good for power. So here are my recommendations:

STOCK AIR CLEANER MODS

• Use a K&N filter in the stock 240 air cleaner. This keeps all the PCV hoses and vacuum lines active, reduces intake noise and gas smell, and makes the engine bay look stock. ZTherapy says that the air horns on the 240 baseplate are actually better than aftermarket airhorns, and flow more than the carbs require so no anxiety is needed when using the stock housing. 
• My second choice would be the individual round K&N filters that use nuts to hold the filters on, not clips. Keep in mind that open air filters bring in hot air from the engine compartment. 
• If you want to repaint your 240 air cleaner, use "Chevrolet Orange" engine enamel. Available from the auto parts store. I don't know what the original color was 30 years ago, but it looks factory to me.

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• The stock Z exhaust manifold is said to actually flow pretty well for street use. Quiet too.
  
  
• A header is used to separate the exhaust runner pulses and allows better top-end breathing by providing more "scavanging" of the gases from the exhaust ports. An interesting benefit is that gas mileage usually goes up. The standard improvement advertised by header companies on motors is advertised at 5-15hp.

While some people claim a header produces no effect, putting one on a motorcycle requires that you actually rejet (richen) your carburetors because it improves breathing so much. In addition, car legend is that the Corvette 427 L88 motor would pick up 150hp just by adding tuned headers. While I admit that a Z engine in stock form wouldn't benefit much from a header, I feel a L28 with a bigger cam, higher compression and ported head demands one. If you create a free-breathing motor that pulls 7,000rpm, putting a stock 2" exhaust on it doesn't make sense. Every road-race car in the world uses headers...good enough for me.

Headers are made of thin-gauge steel because they have to be bent into shape and welded rather than cast like the stock manifold. The result is that they tend to rust through quickly. The solution is to get one with Jet-Hot or ceramic coating to lower heat and improve durability. If you buy a non-coated header, before you put it on use paint stripper to remove the factory paint. Then prep and spray with a quality manifold heat paint. The paint they are shipped with usually flakes off...paint it properly before you put it on the first time.

I've have used the Motorsport Auto 6-2 header for about 10 years and have had no problems with it. In May 2007 I just replaced it with a 6-1 version and their premium bolt-on 2 1/2" system. The header has a thick flange with good clean welds inside the header. The exhaust system exceeded my expectations, with high quality 3-bolt flanges both the in front and rear joints...the exhaust hangers were even welded in place. A monkey could put it on. Good job Motorsport!

If you plan on keeping your Z for another 20 years, I would make sure you have an extra stock exhaust manifold in the garage as a replacement. I suspect Z headers will be difficult to find in the coming years as the these cars get really old.

HEADER GASKET
The MSA header gasket used to be a cardboard fiber material which didn't last very long. Now they are supplying a newer style one with a metallic core which looks very close to the Fel-Pro version. So I have no problem using this new gasket which appears very durable. Again...good job MSA! If you want to use a stock gasket I had no problems using one with my sets of headers. Despite the old wives tale that stock gaskets leak with headers, mine sealed tight as a drum. Maybe that's an old Chevy wives-tale.

TIP: use a fine flat file across all the ports on the header flange before installation to take off high spots and make it flush. I believe this is actually where the leaks come from.

MUFFLER
The search for the best muffler is as long as the one for the Holy Grail. Everyone has their favorite, but no one is satisfied. Here are my experiences and the ones I've tried so you can form your own opinions:

ANSA TIP: I used dual Ansa tips on my '76 280Z in the 1980s. Good idle tone but raspy under power. Thin wall 2" pipe.
MONZA BIG BORE SINGLE TIP: I used one of these single tips on a straight pipe on my '76. Sounded incredible when opened up but the Virginia State Police pulled me over for a noise violation.
SUPERTRAPP 4": I used one of these for about 8 years. Great for tuning the sound using the removable plates. No negatives other than having to keep an allen wrench handy for the screws.
DYNOMAX super turbo-oval 2 1/2": nice refined tone which made the car much quieter, excellent performance. Doesn't fit well under the rear valance though.
MAGNAFLOW 2 1/2" round satin: My current muffler seen below. Fits perfectly and looks stock. Around town has a nice sedate burble, but when opened up above 4k it sounds like a machine gun on 110 octane. The welds have an odd brown tint that isn't rust, I would have it Jet-Hot coated if I were to do it again. I had the tip welded on afterwards.

PIPE SIZE
People have been arguing about whether to use a 2 1/4 or 2 1/2 " pipe for years. If you are doing competition then a 2 1/2" pipe will add more power on the top end, a 2 1/4" works and fits well for the street. Just don't lose sleep over which is best. NOTE: if you have a catalytic converter, you can only 'legally' change the "cat-back" part of the system. Keep in mind that the Monza and Ansa brand systems are only 2" in diameter (boo). Also, the 240Z came stock with a teeny 2" exhaust pipe stock. Kudos if yours is still intact, but I would replace it with a larger diameter pipe.

HEADERS vs HEAD TYPE

All intake ports from 1969 to 1983 were round, the L28 heads have a notch at the top for the injector. Use a carbureted year gasket to cover these if you want to use an injection head with carbs.

• 1970 through 1976 heads have square exhaust ports (E31, E88, N42)
• 1977-'83 heads use rounder, diamond shaped exhaust ports (N47, P79)
• 1981-'83 turbo heads have square exhaust ports (P90,P90a)

In terms of design, a retailer told me that all '77-83 headers are actually identical. The only difference is that '80-83 versions come with an EGR connection. So if you have a P79/P90 on a carb'd engine, just use a '77-78 header. Just don't start swapping stock manifolds back and forth. GET A HEADER!!

So you end up with a stock-looking 240Z with a ZX motor, superior electrical system and ignition, 5-speed, upgraded drivetrain AND a high-ratio rear end. A good old fashioned hot-rod using factory parts! Thank you Nissan for making all the parts interchangeable!