512 Piston to Head Clearance

[BHB4408]

New Bracket Racer, looking for experts on what my Minimum Piston to Head Clearance can be. .40 Over 440 with 440-Source 512 Stroker Kit, ICON Flat Tip Forged Pistons, 12.1 Compression ratio, Trickflow 270 Heads, Steel H Beam Rods. Block has been Line Bored and Decked by a well known Top Alcohol Engine Builder. Pistons are above the deck by .015 - .016. I have Cometic .51 Crush Value MLS Head Gaskets, which means my Piston to Head Clearance is at .035 - .036. I've read that .40 is the minimum, but others are saying they go to .032 to get the compression they want. The lowest I've read is .027. Am I OK at .035 clearance? Thank you for your help!

 

[RustyRatRod]

I guess it will all depend on how high you plan on spinning the engine. I would think .035" would be safe. I'm building another hot slant 6 and plan on down around .020" or so quench distance with a closed chamber head. But I only plan on a red line of no more than 5500. Yours I'm sure will be more.

 

[MOPARMAGA]

New Bracket Racer, looking for experts on what my Minimum Piston to Head Clearance can be. .40 Over 440 with 440-Source 512 Stroker Kit, ICON Flat Tip Forged Pistons, 12.1 Compression ratio, Trickflow 270 Heads, Steel H Beam Rods. Block has been Line Bored and Decked by a well known Top Alcohol Engine Builder. Pistons are above the deck by .015 - .016. I have Cometic .51 Crush Value MLS Head Gaskets, which means my Piston to Head Clearance is at .035 - .036. I've read that .40 is the minimum, but others are saying they go to .032 to get the compression they want. The lowest I've read is .027. Am I OK at .035 clearance? Thank you for your help!

I had .029 and my pistons were cleaning the heads just enough to cause issues.
My pistons are .010 out & now I run the .051 cometic, so .041 clearance.
I would hate to tell you it's okay and it's not.
What does that dude who decked your engine think ?

 

[Newbomb Turk]

There is no way I’d run less than .040 on anything unless you share taking the engine apart to monitor ****.

On top of that, the bigger the bore, the more rock at TDC.

Unless you are going to coat the pistons with Line2Line coatings which reduces piston to wall clearance to near .001ish running.

This ain’t Pro Stock or Comp Eliminator.

You wouldn’t run your intake valve to piston clearance at less than .040 would you??

Set it at .040 and send it.

 

[PRH]

My preference for that kind of build is .050”.

Get some .060” gaskets.

 

[GTX JOHN]

I have not and will not run at least .040 on my stroker big block
bracket engines.

 

[fishmens67]

Out of the hole .040 min, zero deck . 035

 

[gregsdart]

Keep in mind every combo is different, and yours MAY tolerate .035, or may NOT. It is up to you if you want to roll the dice. If you have a tight piston to wall, pistons that don't rock a lot in the bore, you might get away with less than .040, but what is the risk versus reward? Not worth it, IMHO. IF you were building a competitive stocker, then the very little gain might be worth the risk. Keep in mind those guys go to extremes for very minor gains.

 

[BHB4408]

Thank you all for your expertise and advice. I ordered .56 from Cometic and that will give me .040. Hoping that will be good. Thanks again,

 

[MOPARMAGA]

Thank you all for your expertise and advice. I ordered .56 from Cometic and that will give me .040. Hoping that will be good. Thanks again,

Looks like you've got a nice dart in the making from the looks of the avatar picture.