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L18 Engine Rebuild Help for a Beginner


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Soooo I’ve got an extremely long question. I’m planning on pulling my motor next month and buying a rebuild kit so I can learn how to do it. I’ve been looking at a rebuild kit from CleggEngine.com and the price seems pretty decent. But I assume I would need a rear main seal because I’m pulling the motor correct?

And I know the heads need valve work so I’m just gonna give the heads and block to a machine shop to do a small bore and hone (maybe for 280zx pistons) and valve job. What all would the machine shop need to do to the block? I know the heads need some work and valve seats, but I’m just trying to get a price estimate for all of this so I can make sure it’s within my budget.


The main points I need answered are what does the machine shop need to do? Does the engine rebuild kit come with everything I would need? And extremely general estimate for machine shop charge(if possible). Do I need any special tools besides a timing kit? I’M NOT GOING FOR PERFORMANCE, it’s just a “budget” and learning rebuild to get a new motor on the inside. I don’t know anything about working on the inside of an engine so if anybody has any input I’d appreciate it.


Edit: Also planning on getting a Weber 32/36 to replace the stock Hitachi because this thing is garbage.

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I am in the process of rebuilding my engine. I have sent the head out to the machine shop for new valve guides and lapping in new valves.  The block will be bored as needed.  The cost for boring is about $100.00 a hole.  The crankshaft grind is around $300.00 for grind and balance if yours  is in decent shape.  The head work will be the cost of the guides plus the labor.

I am expecting to pay right around  $900.00 when I get it back.  The good machine shops around here have a 3 month lag time so patience is important.    I have asked the machine shop to source the replacement parts he needs i.e. pistons, valves, valve springs etc because he has suppliers he trusts to deliver quality parts to re-builders.  I am reluctant to buy these on the internet from sources I DON'T KNOW.

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L crankshafts almost NEVER need machine work. The are well supported by wide bearings. YOU can check the widths with a caliper yourself and use plasti-gauge to check the main and rod clearances. Why pay machine shop price per hour to do this simple thing?


Turn the cam till the valve is fully and open and wiggle side to side in 4 directions. If you can feel slop you might need new guides.


Older heads used hardened bronze alloy seats on the intakes and without leaded gas to lubricate them they may have sunk. If getting new seats make sure they are the newer hardened steel ones for today's gas. Find a reputable shop for head work, a rule of thumb is a 3 to 5 week wait because they ARE reputable and in demand. If not done right the seats fall out while driving and fuck a piston and the head is junk. Ask around. Yes.... it will cost more but you get to keep your engine.


Sometimes the heads are in good shape, even so replace the valve guide oil seals.


I had my Z22 block bored 2mm to 89mm for $25 a hole Canadian. A gasket kit, rod and main bearings, oil seals, rings, over bore came to $500-$600? New pistons would be more like $100 each. Do not over bore till you have the pistons. Head rebuild would be $4-500. A good (made in Japan) timing chain another $100.



A re-build kit should include pistons (over size and matching rings) so forget the stock 87mm 280z flattops unless bought separately.

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One valuable lesson I learned back when I was building engines for a living, was that most machine shops want to machine every surface of an engine. Whether it be the main and rod journals of your crank, or the deck surface of both the block and head, they always like to cut things... even if those things were perfectly fine. It isn't hard to tell if the head and block deck surfaces need to be cut. All you need to verify that is a block of wood, some emery cloth, a squirt of WD40 and a good straight edge (which can be purchased easily online or on any tool truck).


Cutting the head a few thousandths (.010") isn't a bad idea, as this will give you a slight bump in CR. Cutting the block, however, can put your pistons too close to the head surface.


Grinding the crank, as Mike mentioned, is almost never needed on an L series. If the bearings look usable, or at least not destroyed, the crank will likely need just a polish. The balance is almost always within 4 grams on a Datsun's rotating mass, so before you have them balance anything, ask about price. If the cost is only $100, go for it. Note that sometimes aftermarket pistons may need a bit of balancing, so balancing may prove to be worth it.


If you don't have any experience building engines, but want to build this one, you may consider having the machine shop assemble the bottom end, leaving you to install the head and everything else. There is a lot of nuance that goes into building the bottom end: measuring bearing clearance, setting the thrust, getting the rear main seal and side seals in just right, not cracking a ring when hammering it home. A machine shop will charge you only about $400 for bottom end assembly, but it can cost way more than that to find out that you made a mistake somewhere.


So in short, buy a straight edge, or ask the machine shop to inspect the surfaces while you watch. That's about the only specialty tool you need other than a good torque wrench.

Edited by Stoffregen Motorsports
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28 minutes ago, Stoffregen Motorsports said:

One valuable lesson I learned back when I was building engines for a living, was that most machine shops want to machine every surface of an engine. Whether it be the main and rod journals of your crank, or the deck surface of both the block and head, they always like to cut things... even if those things were perfectly fine.


Lawyers see you as a cash cow

Cops see you as a criminal or at the least... not another cop

Doctors see you as must have something wrong

Mechanics see you as gullible.

Psychiatrists see you as probably having mental heath problems in terms of their own.


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have the block done. I had both of mine done by a shop that does imports.  I got 190K on my 521 motor that was redone.

most like might need a rebore. finding L18 pistons are hard . 4cc dished 85mm

cranks are most likely good. but ck the bearings.


Personally I would just see if you get by just clean up the bores and new pistons.


the side crank seals I would get the nissan ones and give to the engine builder.


find  Jap made timming kit.


if possibel truck is still running buy a hopefull know running more and rebuild it on the side. But if not possible you know your motor is good and dont have overheat issues then most likely its good

Edited by banzai510(hainz)
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brand names?

Nissan head gaskets.

OSK, Tsubaki timming kits, Made in Japan, Not Mellig or Cloyes those use taiwain chains and USA 3 hole sprockets. Might not be bad but cant verify timming marks for cam alighnment

Paurant water, oil pumps(uausally reboxed Hitachit made in Japan

Felpro gaskets are OK for the rest of the motor and the headgasket for a L16 83 mm. on 85mm I would go nissan or Durapro which I get from Datsport in Austraila which is a Jap made graphite gasket in 87mm

 Clevite bearings


But my piston s were ITM brand made in Taiwan and seemed OK as it now has 190k on motor now.


soemtimes thats all is now listed as parts are drying up and most might be more NON Jap made parts



back in the day Beck Arnley, Bap Geon was all just reboxed Factoy parts.


Busta Nut on here was getting good parts from somewhere but forgot the name

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