Rebuilding your 1970-83 Datsun ZCAR motor?
These are the easiest and most satisfying motors to rebuild. The most important things to remember are: keep the rebuild spotlessly clean, and don't use cheap parts.

DatsunZGarage.com

Putting the rebuild back in, always a great feeling!

DATSUN ZCAR ENGINE PARTS SOURCES for 2008

NISSAN DEALER
While I can't speak for Nissan I doubt they have a factory devoted to making parts for motors that haven't been produced since 1983. The Japanese are experts at outsourcing parts (examples are Nabco, Tokico, Hitachi, Lucas, ) nowdays they likely have someone in Asia making parts to Nissan specs. Nissan parts are factory quality with the expected high prices.

BECK ARNLEY
Beck Arnley has been a parts distributor since 1914, they don;t manufacture parts. Due to their high quality and Nissan-like prices, I've always suspected they import parts from the same sources as modern day Nissan. A timing chain set of theirs I purchased in 2006 was labeled "Made in Japan", a welcome surprise. A main bearing set was labeled "ACL" of Australia which is highly respected. I would make them your first choice after the dealer.

FEDERAL MOGUL
The company Federal-Mogul of Michigan owns nearly every other aftermarket company: Sealed Power, Speed Pro, Fel-Pro, Champion, Carter, Ferodo, Wagner, Moog, Wagner, National, Precision, Abex, Anco, and supposedly Crane Marine. This gives Federal Mogul a huge inventory to draw from for Z parts. However, they declared Chapter 11 in 2003 due to asbestos claims. And despite having a wide range of aftermarket Z parts you can bet that L-series parts are becoming less of a priority for them. Buy 'em while they last.

BORG-WARNER (BWD)
Borg Warner is a niche company nowadays and concentrates on high-quality electrical items such as voltage regulators and ignition parts. Their distributor caps and rotors use the coveted brass contacts, I bought a 240Z mechanical voltage regulator a while back which was very high quality. Borg-Warner doesn't support T5 transmissions anymore, they sold the rights to Tremec in the 1990's and won't even respond to questions on them.

DANA and CLEVITE
Dana is the parent corporation of Clevite and in March 2006 declared Chapter 11 bankruptcy. Napa used to carry Dana parts which consisted mainly of bearings sets and pistons parts. Clevite made an OEM L-series camshaft I bought from Black Dragon Auto a few years ago.

JC WHITNEY
JC Whitney is just a catalog company with about a zillion suppliers, they don't produce or manufacture anything. When you buy engine parts, headers, tools, performance parts, you're just getting the aftermarket brands listed above. No secret underground line of parts...trust me.

My Personal preference of new internal Z parts

• MAIN BEARINGS: use factory Nissan. The price is good the tolerances can be trusted. My dealer: $50.
• ROD BEARINGS: Nissan are pricey. Beck Arnley gets the nod here. My auto store: $28
• PISTON RINGS: I have used Beck-Arnley three times with good results, $50. Nissan and Fed Mogul are $$$.
• HEAD GASKET: For non-turbo engine I think Fel-Pro is great, easy to remove too. My auto store $20.
• TIMING CHAIN: Several companies make replacement chains. I would again go with a Beck-Arnley full set for $79.
• MISC ENGINE GASKETS AND SEALS: Fel-Pro and Beck Arnley make a great general gaskets. Rubber seals should be Nissan, always.
• CLUTCH: I like Perfection brand stock clutch or "Zoom" brand for performance clutches.

THE REBUILD
Ready for the project to begin

REBUILD BOOKS
While the Datsun shop manuals show you the procedures, they don't discuss the principles of engine rebuilding. For that check out a few Hot Rod type magazines (Car Craft is the best) and study their engine rebuilding tips. V8, L28, the basic concepts are all the same.

Get both the Chilton and Haynes manuals since separately they tend to be incomplete. The Chilton mainly covers replacing, not troubleshooting while the Haynes is a British version with sometimes odd photos. But between the both of them you can usually sort out a procedure. My favorite is an older book by Clymer which had excellent detailed diagrams and troubleshooting and even a fold-out electrical schematic in back. Sadly, it's out of print.

HELPFUL TOOLS
While it seems obvious to have a decent amount of hand tools before you start, the following ones will make the job go much more smoothly.

• complete 3/8" and 1/2" metric socket set
• 27mm socket for the front pulley
• open ended wrenches (spanners) in 10-19mm
• 10mm allen socket for head bolts
• long 1/2" breaker bar. Craftsman makes an 18", Northern Tool a 24".
• torque wrench, I like the cheaper wand type.
• quality gasket scraper (not a screwdriver)
• tap set and brush-on anti-seize (see below

ENGINE STAND
If you ever wondered, you CAN rebuild a Z motor in the car. If you unbolt the motor mounts, you can use a floor jack under the transmission to lift the engine a few inches. This lets you unbolt the oilpan and take it out with a bit of difficulty. If the oil pickup gets in the way slip a wrench in sideways and unbolt it. You can then remove the head and pull the pistons out. But I recommend spending $50 on an engine hoist and putting it on a stand. Lying contorted under a dripping motor was ok the first time, but my other rebuilds have all been done by removing the engine.

L28 BLOCK CHOICE
According to Nissan, there were 2 different L28 blocks, '75-80, and '81-83. The early block is stamped N42 to the right of the driver side motor mount, the later F54 which has "siamesed" cylinder bores. Siamesed means that additional webbing supports were cast between the cylinders 1-2, 3-4, 5-6 to increase rigidity. While the factory says neither is better for racing, newer is better in my book.

CAM CHAIN TENSIONER
As you probably know, there's a chain-tensioner deep down inside the front cover. This little item presses tightly against the cam chain and is a real problem if you take the cam sprocket off without wedging the chain in place...you'll find that suddenly the timing chain is too short. This is because the slack is taken up as this tensioner pushes against the chain. I've heard of some people levering it back with a long screwdriver, but I don't trust that. If you messed up the chain timing, you should remove the front cover and reposition everything to be sure its correct. A few hours work unfortunately. Get a chain wedge from Motorsport Auto or make a wooden one from a diagram in the Chilton manual to prevent this from happening.

FRONT COVER
Since the oil and water pump are here the mating surfaces on the cover must be spotless upon installation, otherwise you will have an oil or water leak. It's very hard to get the old gaskets off so spend extra attention here. The best method is to use gasket removal spray and then a sharp razor blade to slice off the old gaskets. But be careful not to gouge the aluminum or slice too deep. Then follow it up with fine emory paper on both the cover and engine block surfaces. Forget silicone sealer....use a brush-on gasket sealer like Permatex 300 to seal it tight as a drum.

PISTONS-RINGS-RODS

Flat-top P79

BALANCING
A Z engine is not same as a small block Chevy, yet people insist on using the same rebuilding folklore that their grandfather used. There are 2 methods of balancing car engines. Those that are "Internally" balanced and those that are "Externally".

• INTERNAL drills holes in the crank counterweights to balance it. The pistons and rods are prebalanced at the factory.The flywheel and front pulley are separately balanced and can be changed without affecting rod/piston/crank balance in the engine.
• EXTERNAL uses an unbalanced crankshaft and typically unbalanced pistons and rods. A front "harmonic balancer" and sometimes an offset-weighted flywheel are used to smooth things out and dampen vibrations. Change one and the whole rod/piston/crank assembly can go out of balance.

Many Detroit V8 engines were externally balanced, sometimes times not even the high-performance versions. Why? Likely because making quality parts and balancing thousands of engines on the assembly line was expensive and time-consuming and redlines were low. So crankshafts and rods were cast iron instead of forged steel resulting in breakage under racing conditions. To compensate the factories used harmonic dampers on the front of the crank to smooth the vibrations out and guesstimated everything.

On the other hand, Datsun L-series "ZCAR" engines have been internally balanced since the car's inception in late 1969. Both the crank and connecting rods were forged steel and were precisely balanced at the factory. Remember...this was a sports car with a redline of 7,000 intended for racing, so they made sure to use all the engine balancing tricks to ensure reliability This is likely the main reason L-series Z motors easily turn over 200k miles while American ones of that era were lucky to see 100k. At rebuild time you should still get both the crank and pistons checked at the machine shop. But on my last four L28 engines I have never had a factory part needing rebalance. Go Nissan!

A machine shop will tell you that an inline-6 engine is the easiest to balance because the pistons all move in the same plane, unlike a V8 where pistons are always off axis. This is why they ask you to bring in "everything" (cranks, pistons, rods, flywheel) when you want a V8 engine balanced: they use a complicated series of plumb-bob weights on the whole assembly while spinning to get things right.

A crankshaft with only two ounce-inches of imbalance at 2,000 rpm will be subjected to a force of 14.2 lbs. At 4,000 rpm, the force grows to 56.8 lbs. Double the speed again to 8,000 rpm and the force becomes 227.2 lbs.

As you see in the factoid above, this is where V8 balance is critical because even the slightest out-of-balance piston/rod throws off the balance on the whole assembly... next thing you know you've thrown a rod through the block. Just picture an unbalanced gyroscope running at a high speed!

Remove the weight and it becomes "...a neutral balance unit for internal-balance crankshafts."

CONNECTING RODS
According to the Honsowetz L-series rebuild book, Datsun connecting rods were matched as a set at the factory. Racers like to grind and polish them (Chevy folklore again) but checking the balance is all that's necessary for the street. The factory says to replace the rod-bolts on every rebuild, but if you're being cheap you can get by with re-using the stock bolts. I've built 3 motors reusing the stock bolts, which I have driven very hard with no problems. But for my newest rebuild I went to Summit Racing and got a set of ARP rod bolts, part# ARP-202-6003 which will last forever.

Some people insist that you should get the big ends of your rods recut and resized at rebuild because they will be out-of-round from heavy use. This is another holdover from muscle-car days when cheap connecting rods always needed resizing at rebuild time because they were oval from the pounding of an unbalanced engine. While I'm sure some Datsun rods have required resizing I wouldn't consider it a must. My machine shop laughed when I asked them to do mine...they said Datsun/Nissan rods are so stout it's not an issue but checked mine anyway. They were perfect.

CLEANING
When cleaning off the hard carbon on the piston tops, don't use a wire brush on a drill, or you'll grind into it. I let the tops soak in carb cleaner for a while, and then use a Scotchbrite pad. It takes a while to get it all off, but be patient. Use a piece of broken ring to clean out each groove, and make sure the grooves are PERFECTLY clean with no burrs. Don't use a cheap sponge with Scotchbrite on one side, use a real Scotchbrite pad

RING TYPES
There are three types of piston ring materials used on the face of the top rings: cast iron, moly, and chrome.

MOLY Molybdenum is very porous which results in more retention of oil in the face of the ring and also has the highest melting point of the three types. In continuous high speed or severe load conditions moly faced rings are considered the best choice because of high scuff and scoring resistance. I've read that stock Nissan top rings were moly, and I think Arias makes moly rings for L-series motors.

CAST IRON According the Honsowetz L-series rebuild book, cast iron rings are a good choice for the street in Nissan motors. For typical driving where the car is not subjected to long periods of high speed or on paved streets, plain cast iron is considered very durable. While there is nothing wrong with cast iron, it seems to be used more for stock replacement applications than high performance like chrome and moly. The Beck-Arnley rings I've used were cast iron.

CHROME These are recommended for a "dusty environments such as offroad racing". I'm not sure why dust would be in the cylinders, but chrome's smoothness and hardness keeps dirt from impacting into the face of the ring which can cause cylinder wear. Its resistance to scuffing and scoring is higher than cast iron but somewhat less than moly and it requires a special honing finish on the cylinder wall because chrome is so smooth. Sealed Power, Total Seal and AE Clevite makes chrome rings for the L-series. ITM replacement pistons sold by Black Dragon Auto are listed by ITM as having top chrome rings with cast iron 2nd rings.

CONCLUSIONS: Moly rings are considered the "best" for high performance as they seal well, resist scuffing and are used on nearly all modern performance motors. Cast iron is very durable and seals well, I've used them on the last three motors with no problems. Chrome is good for performance too but requires a special hone finish in the cylinder to break in properly. I wouldn't lose sleep over which is best, buy what makes you feel most comfortable.

RING INSTALLATION
Don't try to install or remove piston rings with your fingers, spend $5 and buy a piston ring spreader. It makes installing them much easier, and reduces any scoring of the piston as well as the possibility of breaking one (as no-one sells single piston rings).

Ring oiling: The Haynes 240Z repair manual says to "liberally" oil the pistons before install which later changed to "lightly" in the later 280ZX version of the book. Confused, I called and spoke to a tech at Total Seal and asked his advice on installing rings. He was very emphatic that all rings should be broken in with only a light film of oil on the cylinder wall, no dipping the piston tops in oil like some old books show.

His reasoning: Except for what sits in the cylinder crosshatching, oil doesn't make it past the bottom oil control ring to the top ring under normal driving conditions. So if you use the the old-timers practice of dipping the piston-top in oil, it actually clogs the ring lands and glazes the rings during break-in. On thinking it through I have to agree: the only thing that the top of a piston should ever see is gas vapor. So I lightly oil the edges of the rings and the cylinder wall, but that's it. Each spin of the motor re-oils the cylinder wall and pistons anyway, let the engine do its job.

BOTTOM END

BLOCK
We're lucky to have these motors. Nissan designed the bearing caps for the crankshaft to tap down deep into the block skirts. This makes the block super rigid: that crank ain't going anywhere! Did you know that some V8 engines have the main bearing caps bolted to the bottom of the block with only a small edge to hold them? That's why it's so easy to spin a bearing on a V8 and why 4-bolt mains are so desirable to keep everything together. When was the last time you heard of someone spinning a main bearing on a ZCAR engine?

GLYPTAL PAINTING
After cleaning off casting flash and grinding down any sharp edges in the crank area of the block, you might consider painting the interior with Glyptal. Glyptal has been made by GE since 1924, and is mainly used as a heavy enamel for armature windings on generators. For years racers and vintage engine rebuilders have been using it to coat the interior of blocks at rebuild time. Oddly, web opinions are few and everyone quotes exactly the same benefits: "...to seal the metal pores, and aid in oil runoff".

To be honest I've never thought of those as problems needing solutions in a car engine, so here are my own reasons to paint the block interior: "...to prevent sludge from adhering to the metal surfaces, the added peace of mind that you've prepped the interior of block and sealed any grit... and that it looks great".

I've seen photos of people lining cylinder head valleys, timing covers, etc with the stuff. Personally I feel that the block interior is the only area that should be painted and that the bearing caps should remain uncoated...the sharp bearing edges and bolt contact surfaces worry me that oil might get under the edges of the enamel. You might be paranoid that the paint might come off someday in the block. But an engineer friend of mine says his company paints the insides of the magnesium transmission housings of their helicopters with Glyptal. And if it ruined the engines of high dollar auto-restorations I think we would have heard horror stories by now. Of course you should grind and prep the metal to make it adhere, and use brake cleaner to clean all the grease off before painting. Eastwood carries cans of Glyptal. Might seem pricey but a little goes a very long way.

IMPORTANT NOTE: as durable as Glyptal is when dry, spraying brake cleaner on it makes it bubble and dissolve into shreds very quickly which is disconcerting. Motor oil doesn't have the same solvent properties, but l'm surprised that this has never come up before that it's so sensitive to solvents. Something to keep in mind.

HONING
Nissan cylinder bores are very tough nickel-steel. While old American engines commonly require a rebore, it's very common to open up a 30 year old Nissan motor with 200,000+ miles to find the factory crosshatching intact in the cylinder walls. As a result it's not always necessary to rebore the cylinders unless you have the need for an oversize piston. If you decide to simply add new rings you can get away with honing the cylinders to roughen or "de-glaze" them. This is standard engine rebuilding practice that many shops do and doesn't take off a very measurable amount of metal.

HISTORY: A cylinder wall may look clean when you pop the head off, but it's not a perfectly smooth or dry finish. Otherwise the piston rings would overheat and seize due to lack of oil. What is done on all engines is to hone a very fine crosshatch pattern into the cylinder wall. This scoring creates thousands of shallow "valleys" that oil sits in as the rings slide past. During ring break-in the rings slide over the crosshatching and slightly "wear" into the metal forming a tight seal.

FLEX-HONE If you want to hone it yourself try a "Flex-hone" made by the company Brush Research. It looks like a bottle brush with a stone on the end of each bristle. It fits into your power drill and lets you hone each cylinder yourself for 10-30 seconds. This de-glazes the wall and creates new crosshatching and is very recommended on rebuilds. The crosshatching should appear at a 45 degree angle to maintain oil.

The model to buy for a L28 (86mm) cylinder is the GBD-3 1/2" (89mm) with a silicon carbide stone. I use a 240 grit which is their finest for honing. My machine shop used to recommend carb cleaner as a cutting oil, but but Flex-Hone says to only use a 10W-30 or their own brand cutting oil. So I used bottle of their special Flex-Hone oil for mine with great results.

BORING
The max safe overbore on a L28 is said to be about .060" although the riskier people have gone out to .100" or higher. Personally I think you should get a little as possible taken off to maintain bore strength unless you're creating an exotic rebuild. NOTE: scrimp on other things but get your block bored properly. Otherwise you will live with blowby and reduced horsepower until it's bored again someday. A quality shop will leave about .004" of material unbored to be used up when they hone the cylinder. So if you decide to get your block bored ask them how much they leave on for honing. If they say it doesn't matter go somewhere else.

bored out .5mm with new pistons

CLEANING BORES
When cleaning out honed bores use a shop towel which is typically made of lint-free cotton, don't use paper towels which are really just sheets of compressed wood fibers that can remain in the metal grain. And instead of using WD40 or brake cleaner use ATF (auto transmission fluid). ATF is a 10 weight oil with high-detergent properties and has an unusual feature: When used to clean metal parts it seems to pull up residue that nothing else will. On my last rebuild I thought the honed bores were clean, but after running a shop towel with ATF through it came out with gray residue. Mysterious and very cool.

CRANKSHAFT
Precision forged steel, this is the very heart of a Z motor. With the stout 7 bearings it's mainly responsible for the longevity and durability of these engines. Japanese crankshafts are generally perfectly balanced, and these are no exception. But if you're doing a rebuild, it's worth getting it checked and polished by the machine shop. The last one I had checked had 140k miles...the shop said it needed NO balancing at all. The rod/pistons from it's motor were all within 1/2 a gram as well. Let's see an American car company from 1983 manage that one! All the shop needed to do was polish the bearing journals on the crank.

FRONT BALANCER
Unless you have a need for AC and power steering and have no choice, get rid of your 3-row pulley and replace it with a 2 or 1-row. I've weighed all three and here are the weights:

3-row: 8 pounds
2-row: 6 pounds
1-row: 3.5 pounds

I'm not going to get into the argument over whether changing these increases performance. If you want a 8 pound weight on the front of your crankshaft, go for it.

One row and two row

No comment

P90 getting the valves replaced

VALVE SEALS
These seals tend to shrink as they age and let oil drip past them into the cylinder...creating smoking on startup. They are inexpensive to buy and are not as tough to replace as you think. People have been using the "rope trick" of stuffing a length in through the spark plug hole to hold up the valves for decades. The faster and easier method I use is to get a foot of clear vinyl hose from the hardware store. I forget the diameter but it should be the largest diameter to fit into the spark plug hole. Just bring the piston to the top of its stroke and push the hose as far as you can through the spark plug hole. It compresses against both valves and holds them fully up. When finished simply pull it out.

Beforehand search the internet and buy a KD 3087 spring compressor which is made for OHC engines. Using this tool with the hose trick lets you whiz down the head and replace each seal in under 5 minutes.

BEARING PRE-LUBE
You should always use a good startup lube to keep the bearings slick on startup to prevent scuffing or seizing. Permatex makes an excellent red, gooey pre-lube in a small bottle. Mixing it 50/50 with new motor oil makes a great pre-lube. Use it liberally on all new bearings and rotating surfaces. GM makes an engine lube called "EOS" sold at Chevy dealers which is also an excellent pre-lube. It used to be high in ZDDP additive but I belive the new versions may not be.

GASKETS

HEAD
According to Nissan, L series head-gaskets should be installed dry (no sealer). I've tried a couple of head-gasket brands and I really like the Fel-Pro brand. It seals well and as a bonus at rebuild it simply pops off the block, little scraping is necessary. I've seen comments that it's thinner than a stock gasket, and may increase compression slightly. I've also heard it may not seal well for turbo motors, but on regular motors I think it's ideal. I very lightly spread Permatex 300 around the water jacket holes on the gasket. This keeps it from weeping coolant from the edges which is a problem on older motors.

FRONT COVER
Fel-Pro makes a great little kit that includes gaskets, distributor base gasket, balancer seal, water pump gasket. Use brush on sealer (Permatex 300 again) and it should seal tight as a drum. Make sure you triple-check to make sure there are no gaskets bits left on the contact surface, a razor-blade lightly slid down the surface can find them.

NOTE: As I said above, be careful trying to unbolt the radiator hose neck on the passenger side of the cover. On the last three covers I've cleaned, the steel bolts were frozen into the aluminum.

Permatex Super 300 brush-on gasket sealer

CARBS
Be very careful not to turn the float bowls over when removing the carbs. Normally gas doesn't touch them, but flipping the bowl can cause the cork gaskets to curl and leak from contact with the gas.

CARB SPACERS
240 and 260's use a thick red spacer, and a thinner one respectively between the carb and intake. I use the thick, red 240Z versions with a 260 intake and '70 SUs on mine. Double check the two balance-tube gaskets as they get crushed over the decades. They can be fabricated by buying "gasket material" at the auto store and cutting them out yourself.

INTAKE/EXHAUST
I have never understood why stock exhaust gaskets are supposed to "leak" when used with a header. It's torqued to the same ft/lb as a stock one, so there's no reason why it shouldn't seal identically. My old Motorsport 6-2 header went through several MSA cardboard header gaskets: I found they would dry out and break into several pieces on removal, even after using anti-seize on them. MSA now uses a new gasket with their headers which has a metallic core and is very similar to the Fel-Pro. I have it on my Z right now with great results. Thanks for listening MSA.

I have also used a Fel-Pro intake/exhaust gasket ($20) with a metallic core. I covered it in anti-seize for easy removal down the road. Well, it seals perfectly, with no black soot around the exhaust ports. Maybe I got lucky, but I consider the warnings of using a stock gasket with a header to now be an old Chevy wives' tale.

TIP ONE: before header installation, use a flat file on the header to file the flange sealing-surface perfectly flat. Headers can have unseen high spots on the flanges which can cause leaks.

TIP TWO: as seen in the cylinder head photo above, use 8mmx1.25x45mm studs in all head bolt holes. This lets you really crank down the nuts to tighten the manifolds.

OIL PAN
Use a straight edge across the pan to see high spots and sealing problem areas. I like to use a brush-on gasket sealer instead of silicone sealer on both sides of the gasket before install. Also make sure the bolt holes in the pan are not dimpled, as they can cause leaks. Hammer the bolt holes flat.

CAM TOWERS
As I said on my Head Page for rebuild info, these can be removed and replaced with no problems. The specs only ask for 10lb of torque on the bolts. Be careful you don't overtighten and strip one out.

SPARK PLUGS
I bought a 14mm tap chaser and cleaned out the spark plug threads when my head was off. Lots of junk came out. Since aluminum threads strip easily, probably not a bad idea. I used anti-seize on the plug threads on install. I never had problems with threads stripping out, but it couldn't hurt.

FASTENER CHOICES

BOLTS
DON'T use the black metric bolts available in many parts bins.While black bolts look great when new, the black oxide they are covered with is not rust resistant and rusts heavily within a few days exposure to the elements. I'm not sure why anyone would make a machine bolt that is not rust resistant, seems like a useless product. The rod and main bearing bolts can be upgraded to ARP versions, you can replace everything else with stainless steel bolts Don't spend afternoons driving from store to store, go to Boltdepot.com as they sell metric bolts in any style or size you need.

METRIC OR STANDARD
Don't insult this car by tapping out a bolt hole and installing a SAE bolt, it has enough trouble staying Japanese looking without all it's metric "bones" being replaced. TIP: While SAE bolts come in a simple "fine" and coarse", metric 10mm bolts come in 1.00, 1.25, 1.50, and 1.75 thread pitches. 8MM come in 1.00 and 1.25. In 25 years I've never found a hardware store that carries all the pitches. Again, go to Boltdepot.com.

TAPS
Do yourself a huge favor, and spend a few bucks on a metric tap and die set. These somewhat unknown tools are used to recarve threads in rusted/stripped bolt holes, and will save your sanity several times over. Try to tap out every hole you remove a bolt from (same size of course) to ensure accurate and trouble free torquing. This especially true on the head, where sticky manifold threads can cause you to overtighten, resulting in stripped threads. Also when the head is off, tap out the all bolt threads in the block. This gives much more accurate torque readings when installing the head. Sears has a good set. In case you wondered, the correct thread for the oil sensor hole on the passenger side of the block is 1/8" -18 NPT (National Pipe Thread). To clean it out buy a "Pipe tap" which is a fatter, tapered tap especially for NPT threads.

ANTI-SEIZE
Anti-seize is a brush-on silvery paste made out of molybdenum disulfide. When used on threads, it keeps bolts from seizing for literally forever, even in wet or high temperatures. Done in conjunction with tapping the holes ensures yourself, and any future owner, a car with easily loosened, but properly tightened bolts. Get it at better parts stores, very recommended. When possible use anti-seize on EVERY bolt on the car before replacing them.

COOLING

RADIATOR
I just bought a new 3-row 240Z Datsun radiator off the internet for $120, excellent quality. Mine was worth every penny: it dropped my temperature about 10 degrees and my needle barely goes over 170 now. If yours is 30 years old it might be time to let it go.

People obsess over 3 or 4 row radiators and lose sleep over which one cools better. Here's what to do: buy a 3-row radiator and if you need more cooling buy a 4-row. But unless you have a some serious needs a new 3-core radiator is going to cool just fine. If you want to use a 280 radiator in your 240, I measured one and it's side frame bolt holes are off too much, and its too tall to fit a 240Z. The V8 crowd has talked for years about using a Camaro radiator which is about the same size as a 240Z model. I used one for a while but found the Datsun version was superior in fit and finish so I got rid of the Camaro model. Keep it Japanese.

FAN DISTANCE
Be careful if you are dropping an L28 with a 3-row front balancer into a 240. The fan clutch is the same, but ZX fan design extends a couple of inches closer to the radiator than earlier fans. And upon flexing, the fan can cut into the radiator. It happened on mine (#$@%!). The reason is that 3-row fan hubs were made longer to clear the long balancer. .

LUBRICATION

MOTOR OIL
The quality of the oils used today versus what was available in the 1970s is night-and-day. Back then they sludged up motors and filled oil pans with glop, it's amazing so many Z engines made it to 200,000 miles using that oil...it really says something about the quality of Datsun engines as a whole. Today's SM API rated oils have much more detergent and anti varnishing abilities and are said to be stable out to 10,000 miles.

HOWEVER....
Older engines with mechanical valve tappets like the L series and V8s with flat tappets (not roller cams) were designed for motor oil which contain a moderate amount of zinc and phosphorus known as ZDDP (zinc diaklydithiophosphate). ZDDP is considered a miracle lubricant for engines and has been used for about 60 years in motor oil and greases worldwide.

While zinc is not directly harmful to the environment, if its burned due to ring blowby it ruins your catalytic converter. So over last decade the EPA has pressured the oil companies to reduce the percentage of ZDDP in their passenger car oils. This extends the life of converters which in turn reduces total car emissions. SM grade oils all have about .08% ZDDP to conform to EPA standards. 2% and higher ZDDP is considered the level to shoot for.

Pressure from the construction industry allows some diesel oils like Rotella T made by Shell to use higher levels of ZDDP which they claim is needed on heavy equipment. However, I don't like the idea of using bulldozer-grade oil in my 7,000 rpm L28, even if it does have more zinc. Starting in 2007 construction equipment had tighter emissions standards, so zinc in Rotella is likely to diminish eventually.

Luckily there is still one company with the guts to market a higher ZDDP oil for passenger cars, in a viscosity that doesn't reduce horsepower: Valvoline. Their VR1 10W-30 racing oil is a quality SH grade oil which simply means the ZDDP hasn't been removed to qualify as a SL or SM grade. Valvoline's MSDS sheet lists it at 1.3% phosphorus/zinc, 1% sulfated ash and 2.5% calcium...which makes for a nice lube cocktail. Valvoline states it exceeds SM levels of protection...so this is now my oil of choice.. The best place to find it is at NAPA stores, the part # is 205, $5.75 a quart on October 2008. It also comes in a 20w-50 version but I think that's too thick for a L28 motor

OIL FILTERS
Oil filters don't increase horsepower or make the engine breathe better...they filter the oil. The particle size considered to cause the most wear is said to be around 15-25 microns in diameter. What you need is a filter which can reliably filter the smallest particle size from your oil supply. Be careful using racing oil filters as many are designed for maximum flow by allowing everything up to 50 microns or so to pass into the engine...which I guess is fine if you tend to rebuild your motor every season.

I remember a few years ago Consumer Reports named FRAM the best on the market and I have used them since 1980 with no problems. However, Fram is starting to include "additive gel" in some filters to "infuse into the oil" which worries me that they're going down the Slick 50 path.

WIX filters appear to be of high quality and filter down to 19 microns. Their advertising is aimed at people who understand engines, instead of the Slick 50 crowd. The filter they list for 1970-83 Z car engines is #51521.

NAPA makes a high-quality filter with part #1521 which filters down to 19 microns and is easy to find. Interestingly, the specs between WIX and NAPA are identical and it appears they may be the same filter. Between the identically spec'd pair I use the NAPA because it's easy to find and the black case looks great against a blue block (WIX is plain white). The NAPA name may conjure up thoughts of truck parts, but isn't that what you want... a quality filter designed for long service duty?

FIRST-TIME STARTUP

Coming out after months of planning

BREAK-IN TIPS
There are a hundred methods to breaking in motors, from running full throttle immediately to babying it for 1,000 miles. I'm not going to discuss which is correct, I'm just going to just list the methods I use for myself. Cam break-in is not covered which has a whole other list of to-do's. So the tips below are for general engine startup.

Bearings generally don't need break-in, what we want to concentrate on is seating the rings against the cylinder walls to ensure high compression for the engine's life. This needs to be done properly early on.

• Immediately on first startup, check the oil pressure and bring the engine up to 2,000, listening for noises, looking for leaks, adding water, etc. Try to use as little choke as possible as the extra gas can wash the oil from the cylinder walls and affect ring seating. Don't race the engine but blipping the throttle is fine. Let the motor idle at 2,000 until it reaches full operating temperature. Once at full temperature bring it down to idle, re-check the timing, synch the carbs.
  
• I don't believe in pampering by letting the car cool down for 24 hours to "set", that doesn't happen on new cars from the factory. Instead, if all seems solid I go for a test-drive as soon as possible. You need a road with little traffic or a parking lot for this next step: Once on the road accelerate moderately up to 3,500 or so in a lower gear, let off the gas abruptly. Let the engine braking pull the motor down to 1,500 or so. Do this 10 or more times in the lower gears, in different rev ranges. This is a well known method which uses the engine vacuum pull the rings against the cylinder walls to ensure proper seating.
  
• After these initial "throttle dumps" do some moderate driving at different speeds around the area. Continue to do moderate acceleration, occasionally backing off the throttle as before using the engine vacuum to brake the motor. Some people say the rings seat immediately, but I like to take my time over the first couple of hundred miles to let the rings seat smoothly.
• Try to do as much driving in this first phase as possible (first startup should be a weekend). Change the oil at 100 miles.
• By the time you get a couple of hundred miles on the motor you will notice the idle is smoother and stable, with smoother revving and all around "better" feel. If your cylinders have been bored properly ring seating is generally quick at a couple of hundred miles. If your cylinders are roughly honed it might take you a 1000. Doing a compression check will tell you for sure.
  
• Don't start doing 0-60 runs with the startup oil in the crankcase as it has pre-lube remnants and other contaminants in it. Wait until after the first oil change and at 500 miles if everything seems stable and tight, start taking the engine closer to redline occasionally. By the time you get to 1000 miles you should be revving the engine to redline with no guilt.

ENGINE TIMING
This is the #1 problem on newly rebuilt Z motors: the engine cranks, with backfires out the carbs/airbox, but won't start. This because you have the distributor oil pump shaft 180 degrees off. I did this myself on my first rebuild, it's very common. There's some confusion on the proper method, this is the secret to getting it right:

• Set the engine to 0 TDC on the front pulley.
• Open the oil cap and look at the front 2 cam lobes, they should be pointing up. If they are down you need to rotate the engine once more to 0 TDC.
• Now at 0 TDC, with the front two cam lobes pointing up, the distributor rotor should be pointing at 9'ish o'clock. If the rotor is at 3 o'clock then you put the oil spindle in 180 degrees off.
• In other words: At 0TDC with the cam lobes up....the rotor tip will always be at about 9-10 o'clock if the spindle is in properly.

• There's a lot more to rebuilding a Z motor but these are the basics. The only way to really learn is to dive in and try it yourself. Luckily a Z motor is very forgiving. The only real trick is watching out for the engine timing and front chain tensioner.

  © 2008
  Z Garage Engineering LLC
  Hamden CT
  
  All mods are illustrative only, perform at your own risk
  This site has no affiliation with Nissan/Datsun.