Ring gap

90sc35thann

Registered User
I am essembling the engine........finally. How much ring gap do folks on here run on the top ring?


I am currently at .018 and I see the ford manual recommends anywhere from .010 to .020 and that puts me well within range but wasn't certain if folks run more than the factory recommended ring gap.
 
Thanks for the post. I put the bottom end together Friday night. I used .023 for the top groove and .024 on the second ring. They were both .018 out of the box which I knew was too tight for forced induction. I did quite a bit of research where it used to be folks recommended less ring gap on the 2nd ring but evidently on forced induction engines it helps compression to run that gap a bit looser as it helps to keep the pressure relieved between the first and second ring which helps keep the top ring in better contact with the the cylinder wall. Well that's the theory anyway. :) I figured I would give it a try. Either way it's still plenty tight to not hurt compression or cause oil consumption issues.

It went together nicely and I would have gotten the heads on if I hadn't forgotten I needed new cylinder head dowels. :( I forgot when i pulled the engine apart the dowels were so fetched up I distorted the tar out of them during removal. I have a new set on the way and should be here on Wednesday.
 
Thanks for the post. I put the bottom end together Friday night. I used .023 for the top groove and .024 on the second ring. They were both .018 out of the box which I knew was too tight for forced induction. I did quite a bit of research where it used to be folks recommended less ring gap on the 2nd ring but evidently on forced induction engines it helps compression to run that gap a bit looser as it helps to keep the pressure relieved between the first and second ring which helps keep the top ring in better contact with the the cylinder wall. Well that's the theory anyway. :) I figured I would give it a try. Either way it's still plenty tight to not hurt compression or cause oil consumption issues.

It went together nicely and I would have gotten the heads on if I hadn't forgotten I needed new cylinder head dowels. :( I forgot when i pulled the engine apart the dowels were so fetched up I distorted the tar out of them during removal. I have a new set on the way and should be here on Wednesday.

Might want to modify those new head alignment dowels to allow for some cylinder head expansion. See this post for info on what we did to the dowels in my motor a few years ago.

http://www.sccoa.com/forums/showthread.php?t=105928&highlight=4.3+SCU+motor&page=5

David
 
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So you cut a half moon on the top half of the dowel to allow the aluminum to have room for expansion? Since aluminum expands wouldn't the head get looser as it gets hotter around the circumference of the dowel?
 
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