VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Installing Rings On A 216

When installing a new set of piston rings on a 216... is simply swapping out the old rings with correct size new rings?

I was told I might have take a ring by itself and place it in the cylinder at the bottom of the stroke. Then use a feeler gage to verify that the opening in the ring is at a certain spec. If not, file the opening until the spec is achieved. Is this the correct way?

First you need to check the bore for size and taper. If this is in spec the ridge at the top needs to be reamed. If this is not done, the new rings will hit and break. Then the bore needs de-glazed with a hone.
Yes,the ring need to be checked that the end gap is correct. Each ring is placed in the bore half way down and checked with a feeler gage.

I'll have to look up the end gap unless someone has that spec handy?

The "common" calculation I have been told is .004" per 1" bore diameter. That equates to .016" gap but I would look for a gap of .015" to .018" in a 4" bore. More than .018" gap I would looking at reboring and new pistons.
Tony

The Repair Manual for 1931 (194 cu. in.) specifies piston ring gap of 0.002-0.014". It instructs gap over 0.014" should be cause to replace the rings. The cylinder diameter is 3 5/16" which is close to that of the 216.

If the gap is not sufficient,at operating temperature the gap could close and score the cylinder. I always go with the high number with the top ring as it gets the most heat. If it calls for .014 to .016, I may even go to .018. I have experiamted on a dynometer with ring gaps up to .029 with no loss of power or performance.

My initial theory is close (.004 for 3 5/16 bore = .013), but I would not go less than .012 total despite stated book specs.

The extra clearance may not cause power or performance problems initially but carbon build up behind the top ring in particular is not desired in the long term even though it cannot be prevented no matter what ring gap there is.

Tony

On a 1947 the manual says the gap should be between .005 and .015.

I took my pistons to the machine shop to make sure to get the right ring set. They measured them and said they are standard size pistons and gave me the rings.

I measured the new ring gap at .020.
What do you guys think, will this be ok?

Another question... The rings that I removed from my pistons had an octagon shaped ring/spring behind the second ring. Do I use this on my new ring set?

The answer to your question(s) is depends. If all you want to do is get the engine running again then use a glaze breaker, install the rings and put the engine back together.

If you want to do the job once then that is likely not the best option. A .020 gap in itself is not a big problem. The problem may be the amount gap between the pistons and cylinder walls coupled with the taper in the cylinders.

The answer to second question is it is probably better to use the rings in the set as supplied. There are several different type compression and oil rings and each had their own pieces to make them work best.

The replacement rings they sold you should have a spring expander behind the middle ring - or - it should be a segmented ring. A segmented ring will have a two piece (or three piece) center ring and a four piecce lower oil ring which will consist of two thin rings with a pair of zig-zaged spacers between.
The .020" gap should pose no problem on an engine that will get limited use.
The original factory rings had not expanders behind the rings, all rings were a one piece cast iron, and w were designed for new cylinder walls that had no wear.
The Chevrolet replacement Chromeflex rings that became availale for replacement in the mid 1950's did not require cylinder wall glaze bustings but most mechanics did it any way.

ChevNut, the set of rings came in a sealed box with three sealed boxes inside of that. The inside boxes were labeled-top groove, second groove, bottom groove. The top groove were one-piece rings, the bottom groove contained as you described two thin rings the zig-zagged spacer with colored ends, the only thing not as you described is the center-ring... it's only a one-piece. Everything was sealed packaging so I'm pretty sure nothing is missing.

Fleetboy
Measure the gap in 3 places (top just below the top of travel, about half way down and close to the bottom) this will give an indication of bore taper as well as a more accurate ring gap.
To be sure the ring is square to the bore turn a piston upside down to push the ring to the different bore positions.
Tony

Years ago the popular ring makers made rings with "expanders for worn cylinders". I think this was a common fix to get it on the road again. Many folks with didn't have the money for a complete teardown and re-bore. I would say that putting food on the table took precedence over a perfect motor!