Don Terrill’s Speed-Talk

Is it possible to use 4.094 bore rings on a 4.087 bore with just a file fit

rocketracer380 wrote: ↑Wed Sep 16, 2020 10:28 am Is it possible to use 4.094 bore rings on a 4.087 bore with just a file fit

I would say yes. The difference in circumference is only about 20 thou. I did something similar in my recent build, had to file about 20 thou and have excellent cranking compression and no blow by.

The ring I used, from Total Seal, was for 3.330 bore. My bore measures 3.323.

.010 bigger than the bore "should" stay "light tight" in the smaller bore and be OK when file fit to match the bore.

.010 bigger than the bore "should" stay "light tight" in the smaller bore and be OK when file fit to match the bore.

Net difference between your cylinder diameter and your ring set is .007" so you will be able to use these rings. Be sure to check gap and file fit as necessary. You will have slightly more radial tension with these rigs, but not enough to be concerned about.

"Any increase in the diameter of the cylinder is being used in, over the designated size, results in an increase of approximately .003″ in ring gap for each .001″ increase in cylinder diameter"

The opposite is also true.

The "issue" isn't tension...and your tension in this instance will increase, not decrease. You're going to a smaller bore, not a larger one. If there is an issue it would be in triangulation, not pressure.