Engine Assembly: Piston Ring Gaps

After the first few visual checks it was time to get serious. The Sealed Power piston rings that I had bought were pre gapped but I was following "How to Rebuild Small-Block Ford Engines" book by Tom Monroe and it instructed to check everything. So I got busy.

I pushed each ring in its respective cylinder and then squared it with one of the old pistons. I removed the top ring from it and then just pushed the new ring in with it.

Then it was time to check the gap with feeler gauges. After going through every ring, they all seemed to have 0,40 mm (0.0157 inch) gap. I did some reading and it was maybe a little tight. Also, I found more modern suggestions that the bottom ring gap should be a bit larger so any pressure that goes through the top ring is not trapped between the rings.

I clamped a fine toothed file to my table and went through the rings once more. I filed a tiny amount at a time and measured again many times until all top rings had 0,45 mm (0.0177 inch) gaps and bottom rings 0,50 mm (0.0197 inch). Finally I removed the sharp edges from the filed end with 600 grit sandpaper.

I will install the rings to the pistons later when it's time to put them in the cylinders.