Ring end gap. If you've built your own engine post up!

[mindless]

So here's the deal. I started putting the bottom end of my ZC back together sunday night. I go to set the end gaps for the rings and am a little worried about the clearances.

Starting from the bottom. The oil control rails had a gap of 0.030" out of the box so I didn't touch them. All four of the 2nd compression rings had a end gap of 0.015" so I didn't touch those either. The top compression rings, for the most part, had a gap of 0.018" out of the box. One or two of the top compression rings were slightly tighter (0.016" - 0.017") so I did file those to 0.018". I was, and still am, worried about that end gap but I thought it may be better to keep it consistent.

Are the end gaps ok? I have been told not to worry about the oil control rails as you offset the gaps anyway. The 2nd compression ring is dead on but the top compression ring just seems too loose. I have asked around and have been told everything from "order new top compression rings" to "don't worry about it".

DOHC ZC block bored .5mm over. The rings are also .5mm over. If I do order new top rings should I get them 1mm over?

Any help would be great. Thanks.

[guest]

I don't understand. You filied down the ring to .0018....

[mindless]

Originally Posted by guest

I don't understand. You filied down the ring to .0018....

What part do you not understand?

Have you ever put an engine together?

[Arachnid]

what is the max end gap spec.? .002in?(been too long since last build) ask yourself...."are these end gaps within spec?" if they are within spec you should be fine.

[guest]

^^ Honestly, I haven't. "One or two of the top compression rings were slightly tighter (0.016" - 0.017") so I did file those to 0.018". I was, and still am, worried about that end gap but I thought it may be better to keep it consistent. "

There all at .018 now right....., What's the spec?

[mindless]

Per JE's site the top was 0.015" for the top compression ring. They listed a a minimum gap of 0.015" on the oil rails so I don't know if the 0.015 is a minimum or not. I'm just going to call JE.

[Arachnid]

from the haynes manual, it says that .006-.012 inch standard(top ring) that would mean that your .018 setting would be kinda wide.
it is .012-.018 for second ring. and .008-.028 for oil control ring. i might add that i would follow the specs of what the book has to say.

[FMYStreetRacer]

you can throw the book out though if you're gonna be boosted or hit it with the gas. once you start going forced indection (not sure if he is) you want the ring gaps wider. i'd just leave them all alone and put them if it were me.

[DontSaveHer]

My ring gaps where about half this big ||

[zeus zore]

Originally Posted by DontSaveHer

My ring gaps where about half this big ||

LOL....

I just finished my ZC and the end gap for the top ring is recommended to be of factory spec, unless you are turbo or using a different type of piston material which could be a bit bigger, factory gap is 0.0060-0.0140. My top ring was 0.0110 if I remember, have had no isues, but you can always check with JE or your machine shop. Good luck.

[mindless]

Yes, this is a boosted application. I guess I should have mentioned that.

[mindless]

Well I just got off the phone with JE and the tech said that, as stated on the site, 0.015" is a minimum and anything up 0.020" is acceptable. So I guess I'm good to go.

[icarusdown]

My Hastings rings said that minimum gap HAS to be at least 'bore-diameter' x .004". All the rings cleared the minimum (.012" according to Hastings) but this was larger than the maximum factory specs for some of the rings (don't remember which ones now). You should be fine.

[AMkrew_1]

Originally Posted by icarusdown

My Hastings rings said that minimum gap HAS to be at least 'bore-diameter' x .004". All the rings cleared the minimum (.012" according to Hastings) but this was larger than the maximum factory specs for some of the rings (don't remember which ones now). You should be fine.

This is good info. We typically go by this at work. .004" per inch of bore is minimum, if it's a N/A street motor. If you're boosted, you need a little more room. Our single-cam motors have nearly a 3" bore. 3" X .004" = .012" minimum for a street N/A motor. At .018", you've got nearly .006" per inch of bore. This is about right for a boosted motor.

When assembling a SBC with cast hyperutectic pistons, the top ring end gap must be significantly wider than the second compression ring. We go by .0065" per inch of bore minimum. This is because the top ring gets cooked at a higher temp, and expands more than the same ring on a traditional cast piston would.

just some useless info for you. Lol!
-josh-

[mindless]

Originally Posted by AMkrew_1

This is good info. We typically go by this at work. .004" per inch of bore is minimum, if it's a N/A street motor. If you're boosted, you need a little more room. Our single-cam motors have nearly a 3" bore. 3" X .004" = .012" minimum for a street N/A motor. At .018", you've got nearly .006" per inch of bore. This is about right for a boosted motor.

When assembling a SBC with cast hyperutectic pistons, the top ring end gap must be significantly wider than the second compression ring. We go by .0065" per inch of bore minimum. This is because the top ring gets cooked at a higher temp, and expands more than the same ring on a traditional cast piston would.

just some useless info for you. Lol!
-josh-

No actually that wasn't useless at all. Thanks dude!