So I recently got a few pieces of my engine back from the machine shop and noticed that my top rings were gapped .002 larger than the bottom (4in bore ls 6.0l). They're .026 top and .024 bottom. Now I investigated this a bit and it seems like the common knowledge is to leave the lower ring gap a bit bigger so that combustion gases cant get trapped between the rings. But then I see guys like denmah actually do gap the top ring bigger than the bottom due to heat at the top of the piston. So am I crazy to worry about this? I'm thinking I'll just open the bottom gap to .026 myself. Also, is it the accepted practice to keep the bottom gap equal or bigger? Anyone say otherwise?

Thanks

 

There is more heat up top, but most widen the second a couple thousandths to keep the ring from fluttering. I thought Matt was doing the same...ill have to go look again.

 

On LS motors I just do 26 top 26 2nd. I've never done a max effort LS build though. Been fine for the 700hp crap i've done.

 

Well I bought a 12 case and did em 26 and 26! Only got through four beers too hahaha. Thanks for the advice guys, no ring flutter in my future

 

on all the engines i build i always gap them both the same as well

 

Just FYI, i've been doing a ton of research on ring gap because the theory has changed over the years, and I wanted the latest opinions on the subject. I've searched many different manufactures, and talked to some machinist/engine builder buddies, and they all say the same.... a wider gap for the second ring is needed to make sure the top ring remains seated against the bore. Equal gaps may appear to work fine, but in reality, how would you know? I personally wouldn't go thru all the work just to second guess it for a couple extra minutes of filing. My 2 cents.

 

That was my conclusion as well. How much possible downside is there to .002 too much gap? Seems like a lot more downside with it too small.

 

It's an interesting topic for sure. One of the things I thought about was how significant it really is in the grand scheme of things. I bet half the people out there, including myself, arent even using feelers correctly, never the less squaring the ring in the bore perfectly. I think that if your gaps are between .020 and .030 and not fully of carbon you'll probably be fine. I really dont think that .002 here or there on a top or bottom gap will make any difference (but I still did it just in case I'm wrong which is often haha).

 

Exactly. If it blows blue and does 140 in the 1/4 who cares hahaha

 

I was taught by some pretty good builders that not much bad happens until you get over .045". Not that you want to run them that loose.

 

Getting them square in a fresh bore is easy, just push them into the bore with a piston, take your measurements with the feeler gauge. The real trick is not overshooting your measurements and getting all the rings uniform. Grind, debur by hand, push into bore, measure repeat 18.762 times per piston, twice... very methodical.