I bought a set of Sonny Leonards BBC heads with the heart shaped chamber. When I put them on my motor, the pistons were hitting the heads where the chamber rolls in between the valves. Sonny told me to relieve the piston and not to touch the head.

TS1955

Your absolutely right TS1955, its usually better to relieve the piston. But on Todd's post he said he already had his engine toghether. Under those circumstances I would have relieved the head also. No rebalancing or metal in the engine.

I see, you were answering russ not doorracer,not as appears,in order. Just looking @ my typo = should read +, sorry.

I ran a drag motor all last year,4.155 bore,.007 cyl.clearance .005 out of the hole and .041 gasket .036 piston to head,shift at 76-7800.When I took it apart 4 pistons had been hitting the head,all on the right bank,the deck clearance on all cylinders were set the same when it was first built.The top ring grouve was still good so i took .003 off the pistons and now have .039.I won't have it apart till next winner to see if they still hit,unless there's a problem.Just saying .036 might be to close in my combo.Bill.

i like to run zero deck with .041" gasket. I ran a 598 on the dyno once that was down to .035" total turning to 7500 and when we pulled it apart the piston part number was stamped onto the head. (it was a test engine and the pistons had a part number eched on the top) That was a 630ish gm piston on a scat H beam rod with .007-.008" clearance.

Just another vote for .040"+

Steve

SORRY FOR CONFUSIONS...I MEANT .005 TOP OF PISTON BELOW THE DECK.THATS JUST A LITTLE SAFETY NET....I DONT KNOW MORE ON THIS SUBJECT

IM ALWAYS INTERESTED IN WHAT MY MOTOR GUYS HAVE TO SAY.THEY BUILT BRIAN METZENHEIMS 540 ENGINE LIKE 7 OR 8 YEARS AGO AND ITS STILL IN HIS CAR, I THINK....WHICH RUNS CONSISTANT MID 7'S!!!

BRIAN METZENHEIM(http://www.metzperformance.com/about.html) WORKED WITH THE JEGS PRO STOCK TEAM AND IS WELL RESPECTED AT THE GREAT LAKES DRAGAWAY UNION GROVE WISCONSIN