I am about to put the crank back in the block of my L24. I bought new engine main bearings from black dragon and i am goin to plastiguage the new bearings. Does anybody know the oil clearance spec for the L24 mains?

I'm thinking the FSM might be a good tool for you. Look at www.xenonS30.com under the Reference tab for the manual. The Engine Mechanical (EM) chapter has good rebuild information and of course all the related specs.

Cleanliness means more than anything (right next to part fitment)! Pretend you're doing heart surgury and the slightess bit of crap in the wrong place means death. Things you can't see, like oil passages, are the places to pay attention. Soap, water, compressed air and a clean place to work are your best friends at this stage.

Jim

Was there a package insert with the rings? These often have ring gap settings.

One bearing shell has a small hole in it, make shure it goes on the block side of the first bearing jurnal, it feeds oil to the timing chain tensioner.

The answer to your question is main bearings are .0025-.0034 inches. Rod bearings are .0025-.0028 inches. Use plasti-gauge.

yes, but i went to xenon z and downloaded a 1973 z FSM and it says thatt the main bearing oil clearance is .0008 to .0028 inches and the wear limit was .0047 in, i think if my reading was anywhere near that i would need a new crankshaft, but the car ran flawlessly before i disassembled it so i doubt the crank will be that worn

Edited May 8, 201014 yr by J Shara

My How to Modify book gives .0025-.0028 inches (rod) and.0025-.0034 inches (mains). The 240Z factory manual gives .0008-.0028 inches (mains) and .0006-.0026 inches (rods). Why don't you plasti-gauge your bearings and see what you come up with. .0026 on the rods and .0028 on the mains would be in the ballpark. The How to modify numbers would give you a little looser engine but if your crank is standard, they're always pretty much on the numbers. Oh by the way.....I don't think your number one main journal has two holes(either would the bearing shell for that journal)......let me know if I'm wrong. Thanks Guy

yes, i was a bit puzzled by zforces post because as far as i know the L20B and the other L series fours are the only ones that have the two front bearing oil holes that feed the chain oil. And would the green plastigauge cover this range, it measures .0010 to .0030, it should be fine right?

Edited May 8, 201014 yr by J Shara

When I build my engines (and I've built a lot of them), I take the crank to a machine shop..... get it checked for straightness and make sure it mics to standard....I also have them polished. If the crank checks out, I install Clevite standard bearings and just bolt her up. I've never had a problem. Datsun engines don't wear unless really abused. In 20 or so engines, I've never turned a crank or rod journal and you usually can't feel any wear on the cam lobes or at the top ridge of the cylinder. It's always prudent to check things though.....let us know what your clearances are and if you have other questions as you go forth! Good Luck.....Guy

Green should be perfect.

Edited May 8, 201014 yr by Diseazd

So on saturday i finally put my new main bearing in the block. I put the grooved inserts withe oil holes in the block and did all the necessary cleaning and prepping of the bearing backs and the bearing bores in the blocks, and put the crank in. I plastigauged all the main bearings and here is what i got. Journals 1,2,3,4,5, and 7 all read .0020 inches oil clearance, and journal 7 read .0015 inches clearance.

Super.....you're good to go!