My motor is now to the machine shop and the guy need the wall clearance... since I bought the pistons with 1000 miles on them from a member, he did not give me any sheets. And the machanic does not know the 420A so well... he knows the 4G63 but was no clue with the 420A.
Mine are 0.020 overbore and 8:8:1 compression.
Ive read some place with 0.0030, other with 0.0035, and 0,0040.
What I need to say exactly to the guy ? And if someone have a scan of that sheet that would be perfect.
#100277, "RE: JE wall clearance, need help fast !" In response to Reply # 1 May-23-07 12:58 PM by dougie2
Originally posted by noboost .0038" is too small. .0040" works but I think it might be too small .0045" is what I'll be trying next time.
Do you have any evidence or are you just guessing?
I have a set of used JE pistons sitting here on my shelf that had a clearance of 0.004" for 3 years of use in a single 420A engine. They've seen nitrous, 30 PSI of boost from a 20G, and coolant temps of well over 250 degrees (not all at the same time of coarse)... and there's absolutely nothing abnormal about the wear that they show. Actually, I'm getting ready to install them into another engine. The only time I heard any piston slap was during startup on a 10 degree winter morning.
So, why do you think 0.004" might be too small? Why is 0.0038" definetely too small (only 0.0002" smaller)? Doug
#100279, "RE: JE wall clearance, need help fast !" In response to Reply # 2
When you said 0.0040 its the space between the pistons and the wall ? So its about 0.0020 on each side ? 0.0038 will egual to a more tight space ? I know JE will expend with heat, on the scanned sheet I see 0.0040 but cant read all information I need a little more on the right of the sheet :/
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