[yzair]

Checked the piston clearance is .009

[BOBCRMAN@aol.com]

A .030" piston will require a .030" ring and a .030" hole. There is no way you can run a .030 piston in a .050" hole.

The required piston to wall clearance is built into the skirt.

I run into similar situations with old retired guys that decide to repair small engines.. Repeatedly having to tell them that you have to run the correct oversize piston in an overbored cylinder. NOT just put oversize rings on a standard piston..They get a bit noisy that way! Plus they smoke profusely...

[BOBCRMAN@aol.com]

Most clearance you can run on that type piston is .003" might be noisy even at that.. .040" oversize is available.. But the dimensions you are getting don't add up..

[lmsport]

.009 is alot of clearance but will work OK as long as you understand that ring and piston life will be decreased.

[cobalt327]

I used a telescopic bore gauge and quality digital micrometer and they were all around 4.050 average...

Well the piston mics out @ 4.030

Checked the piston clearance is .009

You sure this engine wasn't built as a demo derby mill? But if the p to w is 0.009" and the pistons are 0.030", the bore can't measure 4.050".

If you keep this block, have it checked for bore diameter by a shop and sonic'ed and if it's OK to take out to 0.040" or 0.060" over, do that. There's no way you will get a satisfactory rebuild out of it the way it sits, IMO.

So could I use .20 rings and check ring end gap clearance since the bores just under 4.050 or would this be an issue

I think you mean 0.020" not ".20", but either way, no- this will not work.

[yzair]

I rechecked everything the piston diameter @ the skirt is 4.0560
The bores are 4.0550

[BOBCRMAN@aol.com]

Again, the bore is 4.055" and the piston is 4.056 that won't work.

Measure the skirt directly across from the pin bore.It has to read at least .001 less than the bore.

Try this. get an inexpensive set of feeler guages. use the .001 leaf and place it alongside the piston with the end of the leaf at the pin area of the skirt. then place this in the hole. it should have light drag but pass up and down. Repeat this with the next size till the assembly locks up. next smaller is your clearance.

Probably a .060 bore..

[yzair]

Sorry Bob, I entered that backwards bore is 4.0560 piston is 4.0550