What is the best piston wall clearance with Keith Black forged piston. I have .007”(according with KB instruction) and the engine turns with difficult when it’s hot.
I have a 360 .030” over bore, Mechanical Cam, 10.5 Compression Ratio, 185psi Static Compression.

Regards…. Jose Romero

What is the ring gap set on the top ring?

.012".

Why??

I believe minimum clearance in .0015

But if your ring gap is too tight, a kb hypo will expand more and can bust the rings

everything expands when hot. if the ring gap is to tight, it will bind up and lock the pistons in place.

The specs for kb pistons and ring gaps are on the kb site. just search it

From KB site: "street normally aspirated" forged pistons top ring-.016" 2nd ring -.012"

Did you make sure you had good engine/body ground cables and the right size? This particular question can bite a lot of people in the but.

could you hook up a batt up front so that when it is warmed up & acting up & dragging you can see if it's a voltage drop issue or an engine friction problem.

In resume:
Piston Wall to Cylinder: .015"
Rings Gap: First: .016"/Second: .012".
Is That correct??

In your 1st post you have .007" ptw with forged pistons. What do you mean "in resume"?

in your 1st post you have .007 piston to wall clearance with your forged pistons, & in the next post you have .012 top ring end gap clearance, correct so far?

on their(KB) site they want .004 piston to wall clearance on the top ring for each inch of bore with forged(not hypereutectic) pistons(If I am reading their site correctly,it was a little confusing) which would put you at .016" for a street normally aspirated application(the top ring). At .012 you are tighter than they recommend but I dont know if your rings are butting & causing the problem or not but the more I think about it I would be inclined to think the rear mounted battery & long cables are the culprit. When its warmed up it cranks too slow & this is the issue right? At that point in time could you pull the plugs & see how it cranks & also with the plugs out put a socket & breaker bar(or torque wrench) on the front harmonic dampener bolt & see how hard it is to turn ? or easier yet at that point in time get a jump directly to your starter & dont use your trunk battery & see what it does. It is midnight here & I am going to have to sign off. I will get back to you tomorrow. Post what you find out.