As I am doing an engine rebuild my question is how important is it to have the piston ring gap as shown in the repair manual? I went with having the gaps of the piston rings 180 opposite of each other. What was the significance of what they shown in the manual compared to what I did? I believe I am ok but then I want to hear from some experts on this. I always was told to have them 180 deg apart from each other. I installed the pistons to the cylinders already but I can remove them now and adjust but this would be more time and work.. But doing it right with no problems is what I am shooting for.

"Been there and done that! Well Not everything.
65 500 2dr Coupe
63 Greenbrier

I think I found my answer but it looks like in any case it doesnt really matter? They rotate. Piston Ring Position

"Been there and done that! Well Not everything.
65 500 2dr Coupe
63 Greenbrier

I've got a weird 120 degree sort of but not really method that I can't really describe. I certainly wouldn't go after them unless they were all lined up and what you describe should be okay.

Jim Brandberg
Isanti, MN
CorvairRepair.com

120° apart gaps means the gasses do not have a direct straight line to flow past the gaps when they are first installed.

But, they do seem to rotate in use.

As long as they were not in line, I wouldn't worry.

Frank DuVal

Fredericksburg, VA



Edited 1 time(s). Last edit at 03/10/2023 10:46AM by Frank DuVal.

I do them as described in the Manual, if it did not matter I would think GM would go into detail with a picture of how to align the gaps.







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

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Rust Free Lancaster Ca



Edited 1 time(s). Last edit at 03/12/2023 02:03PM by 1966-Corsa-GT-180.

I assume few of us observe it..., but I wonder if there is a consistent pattern to the position of the ring end gaps when an engine is disassembled. Does it remain at the same "clocking" difference as assembled - even if the rings do rotate?

Or do the end gaps eventually (on a well worn engine) wind up on the thrust side of the cylinder because that is where the greatest wear is (creating a depression) and the end gaps would expand their greatest (getting trapped) at that position?

I rebuilt an engine for someone a few years back, an engine that had been rebuilt with a few miles on it. It had an oil consumption issue. Cylinders had the piston ring gaps all lined up. With the pistons still in the engine, you could just barely see straight into the block. With my reading glasses on. lol I usually do what the manual states.

--------------------------------
Ronnie
Southern Maine.
www.dirigocorvairs.net
66 Corsa Convertible, 140, 4sp.
65 Monza Convertible, 110, PG.




It doesn't leak, it's marking it's territory.

A mirror is a reflection of the miles travelled.

davemotohead Wrote:
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> I do them as described in the Manual, if it did not matter I would not think GM would go into detail with a picture of how to align the gaps.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Since GM wrote the book in 1960's a lot of information has come to light about piston ring behavior they never could have known.

>>>>>>>>>>>>

Do they need to be staggered with the initial build? Yes.
Is it imperative that they be exactly the 120 degree pattern? No.

I build all of my engines by putting the top ring gap on top or bottom, the second ring 180 opposite, then I put the oil ring spacer gap top or bottom then the 2 oil ring ends opposite one another over the piston pin ends.

Yes the piston rings rotate some when the engine runs

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com



Edited 1 time(s). Last edit at 03/12/2023 02:06PM by 1966-Corsa-GT-180.