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 Post subject: Piston Ring End Gaps?
 Post Posted: Fri Feb 25, 2011 3:39 pm 
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Joined: Tue Apr 18, 2006 6:38 am
Posts: 11631
Location: Coming At Ya!
Just opened up this Total Seal ring set today and was looking at the instructions on end gaps. They say that top ring is .0045 x bore and second ring is .0035 x bore??? It's my understanding that if the second ring doesn't have a larger end gap than the top ring that pressure building between the top and second ring will "lift" the top ring and cause it not to seal? :-k

The last set of file fit rings I used were gapped at .018 top and .025 second. Anyone have a reason to do any different this time? :-k

Big Boyz Toyz!


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 Post Posted: Fri Feb 25, 2011 4:20 pm 

Joined: Wed Jan 12, 2011 1:28 am
Posts: 140
Location: N.W.
I just re-visited this last week and a few professional builders I've spoke to continue with that same approach. 2nd ring gap is larger to help release pressure under 1st ring to aid/help compression ring seal. That's how I just sized mine last week. I'm actually tightening my top a little and opening my second a bit more for this build. This is a BBC build if that matters.

 Post Posted: Sun Feb 27, 2011 11:27 am 

Joined: Sat Feb 24, 2007 6:55 pm
Posts: 847
Location: NW MO.
I think I'd stay with having the second ring the same or a little wider than the top ring. If they are the same gap cold, I can't see the second not being more than the top one when they are at running temp.
The second is an oil scraper, so on a 4.155" bore, .005" more end gap will result in an additional .000383% more bore circumfrence not scraped by the second ring. (That's if my math is right)

And I'm not sure I'd narrow the gap much more. I think having them butt will cost more power than having a couple more thousanths gap.

Slow racing is better than no racing!


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