The piston rock is making things difficult to get nailed down. We followed JE’s recommendations for piston and ring clearances, but this introduces a good amount of rock at TDC. Tightest is right around .004 with the deepest about .018. Averaged out, I come up with .0105 (let’s call it .011). Those measurements are combined averages including rock at the intake sides and exhaust sides. If I measure at the wrist pin flats. I come in at .012 as an average. I know the piston will expand thus eliminating some rock and that rock really is greatest on the power stroke anyway. The head-scratcher for me... should I focus on the average numbers or should I focus on the absolute minimum measurement? I’ve probably answered my own question based on how I explained (expansion, rock on power stroke, measurement at the writ pin), but I’d like to know how others are going about it. I want quench to be good, but I also don’t want pistons crashing into the head at 5600.

I’ve held off on ordering head gaskets because of this. The .027 Cometic with the wrist pin measurement goes right at .039 and .038 at the averages. Taking minimum clearances, it ends up at .031-.032. That’s too close and would make the .039 Fel-Pro a safer choice. But the averages put the clearance over .051 (minimizing quench benefits).

Lastly, how important is all this with AFR’s very efficient chamber? I’m not running old GM heads.

What do you guys think?

Any thoughts on engine colors?

Currently, the one short block is gloss black. The heads will remain anodized and I'll probably spray some clear on the exposed areas (once all the MPI brackets go back on, and the heat exchanger is sitting up front, you won't see much anyway). I was thinking staying with black including the intakes. My valve covers are Merc blue. One of my intakes is Merc blue. Maybe pulleys and intakes Merc blue to match valve covers? I had also thought of bringing in some of the boat's Palm Beach colors, but not sure I want to do that.

Any thoughts or pics to add?

I don't believe the efficiency of the chamber means squat if you don't get the quench right first. I think you are on the right track, hopefully someone smarter than me has some definitive information to help you choose the correct thickness gasket. I wouldn't order up a set of .039's just yet.

Thanks Tyler, I hear you regarding the chamber.

I'm going to post this up in the tech forum to see what sticks.

I should rephrase my reply to mean that if the quench isn't nailed down then the chance for knock is going to be much higher thus requiring less total timing and higher octane fuels which really starts to go against what you are trying to accomplish. When I think of chamber efficiency I tend to first think of max power at least amount of timing. Thats why those LS engines are so amazing, they don't require **** for timing and make awesome power and seem to be fairly efficient.

I don’t think you have anything to worry about with regards to piston to head interference. I’m would check piston to valve with some clay and pick a gasket that gets you closest to your target CR. The aluminum heads are great for heat absorption and providing a little buffer where detonation is concerned so you will have some forgiveness on those cylinders that measure slightly closer to the top. These things are going to make great power and there isn’t anything wrong with going a bit safe if you feel like you are close.

Thanks Roscoe!

I posted a question about quench and clearance in the Technical forum that’s just starting up. There was a suggestion of using solder to check. I’m thinking. I’ll bolt a head on using a .039 as a control (it’s been handled plenty during the surfacing on my heads so not worried about it getting messed up). I have some .090 solder that will tell the tale with the .039. Fro. There I can judge a safety margin. Sounds like a pain to do all this, but for me it’s interesting... any reason to get out to the garage is fine by me!

Scotch doesn’t help with replies. FYI.

Caught the virus this week. I'm winded by the time I make it downstairs to just get a drink so everything is on-hold until this passes. Was making great progress too. UPS keeps delivering parts so at least they're making it here,

Crap...I hope you start feeling better soon! Stay strong!