Here’s what the factory wanted for piston to wall clearance.
As you can see as the compression went down and the exh gas temps went up the engineers wanted more piston to wall clearance.
I would suggest to you that since you are saving money with your rebuild by not boring, that you put a bit more back in by getting a Total seal gapless top ring and then run a reverse twist barrel face moly second ring like the motor came out of the factory with.
The moly face top and second ring are why Pontiac cylinder walls last so long.
Be sure to take the hours that it will to break / lightly roll over all the 90 degree corners on all the rings .
This will stop these edges from digging into the walls and scratching them and also digging into the pistons.
Besides being rewarded with having no added ware taking place to the cylinder walls you will also have less friction and cooler water temps.
The ends of the oil ring rails being that they are hard steel are a big culprit in the scratches seen on cylinder walls.
If you do any rolling over of the corners of any of the rings then it should be these.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
Last edited by steve25; 06-11-2023 at 10:57 AM.
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