Piston ring gap.

[Kern Dog]

I'm building the original 383 for the car. I had it bored .030 with Speed Pro forged pistons. The rings are Sealed Power Moly coated.
The top rings checked out with 6 having a .020 gap and 2 having a .022.
The second rings are tighter, 5 being .020, one is .025 and the others are .019 and .018.
I don't recall the rule about the difference in the gaps. I thought the second rings was supposed to either have a wider or narrower gap.
Of course it is too late to call Sealed Power and the weekend is here!
What is the general rule?

 

[Kern Dog]

Looking around, it seems that I am finding that the second ring should be slightly wider than the top ring. The theory is that IF the gaps are the same, the second ring can trap some gases that get past the first ring and trap pressure between the 1st and 2nd rings, causing the 1st ring to flutter and not seal.
I'm going to dust off the ring filer!

 

[Fran Blacker]

They have ring gap charts on line.

 

[vance.dykes]

Looking around, it seems that I am finding that the second ring should be slightly wider than the top ring. The theory is that IF the gaps are the same, the second ring can trap some gases that get past the first ring and trap pressure between the 1st and 2nd rings, causing the 1st ring to flutter and not seal.
I'm going to dust off the ring filer!

when i bought a ring set there were instructions on gap depending on use . or there web site should have some specks.

 

[69Bee]

The piston clearance for those pistons (L2315F-30??) is a minimum of 0.0015", and I would probably go 0.0020" to 0.0025" myself. That being said, the bore might be a smidge larger extra clearance by the shop that honed the block, and would guess that is the larger ring gaps from a stock ring set. The one that is at 0.025" is odd. I like Hastings rings, and they usually are good on the size. A file fit ring set would fix your issue though as they are usually 0.005" larger than the bore size.

As for your question about gaps, stock sets for older domestics are usually the same for top and second usually, while newer motors will have sets with larger second rings. I would run yours as they are, and would not make them any larger, but if you get a file fit set, you could go 0.016"-0.018" on the top ring, and 0.020"-0.022" on the second ring.

 

[Glenwood]

I'm no expert, but here is the chart I followed from Carrillo if it helps.

 

[oldbee]

Ring gap I can't remember. But I'll tell ya to follow directions with moly rings. Mine was smoking but I ran the protocol and within about 10 power/vacuum cycles those rings were seated in beautifully.

 

[67belvedere/225]

they have a sexy ring filer with dial gauge on it at summit,

 

[Kern Dog]

I went back and rechecked the gaps. The .025 was wrong. I must have had the ring in out of square.
They were really close to the size of the top rings so I filed them all to .025.
Thank you everyone!

 

[67belvedere/225]

I went back and rechecked the gaps. The .025 was wrong. I must have had the ring in out of square.
They were really close to the size of the top rings so I filed them all to .025.
Thank you everyone!

Post pics of your build

 

[Kern Dog]

Post pics of your build

It is an ongoing project already 37 pages and growing ! 383 build starts at # 707.
https://www.forbbodiesonly.com/moparforum/threads/lookie-what-5000-buys-you.178346/page-36

 

[Mopar Man 73]

I'm no expert, but here is the chart I followed from Carrillo if it helps.

View attachment 1009436 View attachment 1009437

Thanks for recommending our piston ring end gap chart! I answer these sorts of tech questions all day long at work. I custom cater end gaps for different applications when I have further engine data from the customers. You guys are welcome to hit me on this forum or call/email me at work with piston/piston rings/connecting rod questions.
[email protected]