My old stuff says 80mm 3.150. 3.1492 on the pistons.
Yes, the oversize thrusts are an issue, but only with oversize bearing sets.
(never seen one with a standard set)
Some bearing manufacturers make the thrust surface oversize so that the crank
grinder can clean up the thrust surface for you.
Other bearing sets run a std dimension thrust surface on oversize sets.
When ever you get a crank turned have the bearing set first and take the thrust
with you to the grinder!
Jim Tyler
The way to "file" the thrust surface is with 400 grit sandpaper taped to a
piece of
glass. Use oil. Finish with 600 the same way.
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From: Thomas Walter[SMTP:walter@omni.sps.mot.com]
Sent: Friday, September 03, 1999 3:17 PM
To: datsun-roadsters@autox.team.net
Subject: G engine -- Bore size
OK you trivia buffs, what is the correct size
of the "G" 1500 engine bore size.
Charlie Hubbard stopped by yesterday with parts
of his 1500 engine in the back of his Explorer.
We did the visual inspection, and everything looked
great! Only one I kept hanging up on was the pistons
were standard. But pistons were at 3.140" Bore was
at a few thousands bigger. Thankfully no taper, no
oval shape, to the bores. Charlie lucked out!
Still I'd like to confirm the bore size, as my only
notes have 3.150" inch... so you can understand why
I was scratching my head trying to figure out if the
pistons were oversize or not. After a little carbon
cleaner on the piston tops we could find "STD" marked
on them, confirming standard sizing.
On the THRUST SURFACES (middle cap), there was a good
question. Do you have to "file down the surface to fit".
Typically those thrust surfaces are too keep the crank
from sliding back and forth. You want about 0.001 to 0.006"
end play on the cranksahft, limit around 0.010". For the
life of me, I never remember needing to "sand down" a
thrust surface to fit. Once again, I am ONLY talking about
the Datsun Motors. Just wondering if anyone ever ran into
problems with oversize thrust surfaces.
Little Humor: my straigh edge showed about 0.003" warp on
the cast iron head. Flip it over, and it didn't! It was a
uniform 1.003" wide x 1/8" thick. The entire straight edge
was warped 0.001 5". So after checking the warp with the
straight edge checked both ways.. total warp at the head
was only 0.001 5".
Cheers,
Tom Walter 67 2000
Austin, TX 68 2000
P.S. Long three day weekend... I am planning to get into the
garage to crank out some of those smog plugs this weekend.
Still behind, but hopefully will get some made this weekend!
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