VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Cyl size 31 chev 194

Just starting rebuild on motor. book says cyl should be 3.30 inches or 3 5/16 I have 3.34 looks like somebody honed or cut the cyl that size. There is no ridge at all on the cyl. the pistons and rings are standard. Doesn't appear to be any taper on cyl. Should I bore it out or just throw new rings on it. The second and oil ring both have expanders on them. ring gaps are too huge to measure. Could almost use a 50 thousands feeler gauge if i had one. It really just has to run and was running before previous owner let it sit until it seized. Are oversized rings still avail for this engine. Thoughts anyone?

For me it would depend on how the piston fits into the bore. If they are iron they have very little clearance..

I have a bunch of these rings for these 3 5/16" pistons. But I need to know what thicknesses of all 3 rings are on your pistons and maybe then I can help with some new rings.

bwbugay@aol.com

I can get a 15 thousands feeler gauge between piston and cyl. Ring grooves are 1/8 for both compression rings and 3/16 for the oil ring. The are not cast iron (non ferrous maybe cast aluminium) If you have oversized rings would be great

The piston fit is measured at the lower part of the skirt.

As CHEVNUT noted you need to properly fit the pistons. Chances are good that most cylinder wear is on the thrust side and the block will need to be bored for proper fit. A common size would be .030 oversize. That would be easiest to get replacement parts for. I suggest you speak to a qualified machine shop that can explain the entire process before you get too deep only to end up with a less than expected rebuild. I don't know the correct piston clearance but am guessing it is somewhere around .003.

I have .003 opposite the the piston pin and .006 on the pin side on the bottom of the piston

I have checked my ring supply and do not have the .030" oversize rings . sorry !!!

The original spec for fitting was "pass on .002, lock on .003" with .001 max taper or out of round.
So you are good to go.

3-5/16 is 3.3125.
Figure out your oversize from that (3.34?? from your first post minus 3.3125 would be around .030?? oversize).
So, find a set of rings for a .030 over 3-5/16 bore.

For best results you should lightly de-glaze the cylinder walls leaving a cross hatch pattern when done.
The best tool to do that without removing too much material from the cylinder wall is what we called a flex hone.
Looks like a bunch of balls on the ends of a bunch of wires.

Good luck! 🙂

any idea where i might search for these oversize rings I like that idea more than going 030 bore out and new piston and rings Another question what would I gain in drivability with a new set of 030 pistons?

Alternately would rings for a 030 oversize piston from the filling station work?

Yes these rings:
https://store.fillingstation.com/detail/AF-403/Chevrolet_192936_PISTON_RING_SET_1818316.html
will work.

You will need to specify the .030 oversize when ordering.

But first, verify that your bore is 3.3425" or thereabouts.


If your clearances are as you wrote above, I see no good reason to replace anything but the rings.

I sent you a PM.