jskorz

In the process of rebuilding my 455 .030 over , using Keith Black Hypereutectic pistons ... Total Seal rings . Car will be 99% street use , I have set the top ring end gap @ .020 " ...... 2nd ring end gap @ .024" .... should these clearances be good for my set-up ?

Thanks in advance.

BillK

You need to read the instructions that came with your KB pistons. They will have a chart and will tell you the top ring "end gap factor" You multiply that by the bore size to get the top ring gap. It will probably be more like .027 for the top ring.

If you lost the instructions they are on their web site

matt69olds

If all else fails, read the instructions!!

I wouldn’t guess, call the manufacturer to get their recommendations

The old rule of thumb “3 to 4 per inch of bore” comes to mind. Meaning .003-.004 per inch of bore.

im not a professional engine builder, but I think most builder set end gap a little looser than the rule of thumb for a performance engine, especially one with power adders. They also like the second ring to have a little more clearance than the top ring to prevent it from unloading under heavy throttle.

BillK

The Keith Black piston instructions call for .0065" per inch of bore size for the top ring for "street normally aspirated" engines. That would be around .027" for a 4.155" bore. I dont know exactly what js is doing with his engine so he needs to look at the instruction sheet and decide for his application.

For the second ring I would go by the recommendations that came with the Total Seal ring set.

cutlassefi

Hypereutectic pistons retain more heat in the top area of the piston so consequently they need more end gap.
Bill and Matt are correct, read the instructions or call the manufacturer.