End Gap Mistakes That Will RUIN Your Engine

A little loose and nobody knows...a little tight and everybody knows...

It's the installing mechanic's job to verify the end-gap and not the machine shop's. I rebuilt this guy's engine block and ordered his parts, and he put the engine together himself. He overheated it because the ring gap was not set for a turbo application - he blamed me for not verifying the ring gap before I sold it to him. I told him that, "that's like blaming the gas station clerk for not checking the condoms for holes after you've used 'em." It's the installing mechanic's job to verify the ring gap. Olympia Engine Builders.

45 years ago I called TRW and asked what ring gap to run for their forged pistons on gas. Their answer was .004 per inch of cylinder bore. Never broke a ring, never scratched a cylinder.

I have the same beliefs on the three ring gaps, but I try to take into consideration two more things; How much will the rings close up at operating temp? The top closes up much more than the second. You have to anticipate that and adjust accordingly. Also, how much does the ring open up as it seats? A C-33 AP steel ring may not wear the face at all, so it’s gap stays consistent after break in. The second ring, being a tapered face, will open up the gap .00314” per .001” of face wear. per side, which means .00628” more gap, per .001” combined face wear around the ring. That second ring can open up .020” pretty easy. So keep that in mind. This is often the reason people see a power increase “after the rings seat”. It’s not that it’s sealing more compression, it’s that the ring pack starts working better because the second may have been too tight initially. Something else to consider about blow by and gap is, on our drag outboards, some pistons only have one ring, and others have both gaps aligned on a common pin, installed from the top. They still hold 2% leakdown, no problem.

I've always run tighter second gaps and had many conversations with guys that did too, never put me wrong and never a blow up from it, BUT I'm building a serious tarmac race car ATM and think I'll pull the bottom end back down and try the larger second ring gap as the rpm is up around 8200 with this motor so it can't hurt to try a bigger second gap, thanks for the good explanation, never too old to learn a new trick 😊

Glad this video popped up in my feed! Always good to see Lake JR on a video. Great information and tons of good concepts to think about. Gonna be taking a lot of this into consideration when I get the rest of my parts to finish my 410 windsor blower motor and have to set gaps.

Good information. Thanks guys. I have been opening up my second gap for a few years now. Thanks for sharing. Take care, Ed.

maaaaaaaaaaaan oh MAN! This is some of THE best ring information I've ever listened to. I have always wondered if there was a gap difference between n20/turbo/alcohol/n/a, etc... Thanks tons, and have a happy 4th !

I really like Jimmy; what a personable and knowledgeable guy. He's the kind of guy I would enjoy sitting down and having a conversation with.

This video clears out so many doubts, wish it had been around when I was building my motor. Would be interested to see you guys discuss piston to wall clearance.

Thank you sir. Your expertise is ao great to hear. Ill follow this on my next build. I love that you are so humble for a man whose been 277mph at Bonneville!! God bless! you!!!

Guy's, thank you so much! This was a huge help and it saved me time and money. God bless you both!

I debated myself for weeks on what to do for end gap on a 225 V-6 Dauntless Jeep Engine. Cost of boring and line honing in my area is not cheap, plus the fact many machine shops have closed down over the years, also could not get .020 rings due to several factors , they weren't available. The Cylinders measured out just over 3.75 to 3.77 throughout each. So I honed them myself and ordered standard rings and installed with 28-32 gaps....Sure that's a lot....but these little Odd-Fire engines run pretty warm too.......still waiting for the heads to get finished 4 months at another machine shop. It's become impossible to rebuild motors fast anymore.

great to hear from Lake Speed Jr again !

This is making me feel better..I'm building a Honda engine for a guy It's a d series... I tried to offer him a better engine but he wanted to stay factory and just build it... So, we had custom wiseco pistons made for this engine 75.5 mm bore, stroke is .163 mm longer than factory rods...when I was checking the ring gaps they were a little bigger than what was specified on the sheet from wiseco...there was three different end gaps... street ,street /strip, nitrous /boost... Well the gap is slightly larger than the nitrous boost gap setting but this engine is going from 9-1 compression all the way to 11: 00-1...The bore is exactly on par and the Pistons measure exactly on par with the correct clearance.. My machine shop guy says it'll be just fine... I think it was like 26ths... The biggest setting on the sheet was 24... I think it's about 2 to 3,000s More than the biggest measurement... This engine will never see a turbo but there's a possibility he might put a 50 shot on it at some point so I guess the slightly larger ring gap is okay....

Man such a wealth of knowledge. I messed up and did a gapless top ring on my turbo rb25 and until it gets hot at the track it smokes a decent amount. I’m not pulling any vacuum on my catch can and it seems like that could be my main issue w using these rings. That or I never seated them properly lol. Great vid!

Thank you for including high performance diesels in this discussion. It makes a lot of sense

Great information I had to watch a couple times ,built many engines and always went by the charts looks like it's time to widen the Gap, Thanks for sharing!

It's amazing how if you take the oil scraper rings and bend the ends so they point back towards the piston skirt instead of having that /\ outwards, the pistons just glide in the bores instead of needing to be tugged on. And this was $0 mod was worth over 20hp on my friends car, LOVE things like that and thats what the name of the game is here!

As long as you lead the race or being in second 🥈 will ingest less dirt than anywhere else on the track. Bravo 👌👏 on that one Lake and Mr. Barton. Thanks again for sharing this with us Mr. Speed Jr!