Piston ring end gap

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Model T Ford Forum: Forum 2009: Piston ring end gap
Top of pagePrevious messageNext messageBottom of page Link to this message  By coreywalker on Thursday, December 31, 2009 - 10:01 pm:

What is the gap supposed to be between the ends of a piston ring when in the cylinder? This ring was on a stock piston in a 1919 engine, the ends are cut on a 45. There is a large gap, at least an 1/8 maybe 1/4". It's hard to see in the picture but it's worn twice as much on the gap side, I suppose fron compression entering and forcing the ring outward more on that side. Were original rings on 45's or straight? The new ones are straight (for cast iron pistons). Or at least they were 15 years ago.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey on Thursday, December 31, 2009 - 10:33 pm:

When a ring wears the gap will naturally increase. I have seen the angled ends but that is unusual.
The ring gap for the engines we talk about here should be about .004 per inch of bore.
That figures to fifteen thousandths of an inch(.015")
The bottom (oil) rings can be less.
I would give the top ring .016 and the second .015 and the oil rins AT LEAST .012.
If you give the top ring .020" I'll not say bad things about you.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR. on Thursday, December 31, 2009 - 10:57 pm:

I have heard that .012-.013 is the number to shoot for. My 91-year-old T guru says .020 won't hurt a thing.


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