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Discussion Starter · #1 ·
Im building a 3o over 454 with mahle forged 11 to 1 dome pistons with 781 casting heads and the piston hit the head ive tried different heads and same thing , has anyone had this problem before?
Any sugestions would be helpfull thanks Joel
 

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Many aftermkt pistons are designed for rectangle port heads. The combustion chamber on oval port heads is designed a bit differently and the piston will contact the head on the exhaust edge of the dome. This used to be a constant problem with TRW, Speed-Pro, Manley and Fed-Mogul (all four use the same forging blank/pistons).

The easiest cure is to use a cutter and relieve the piston around the exhaust/deck area untill it clears the head with no gasket installed.
 

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rat_crazy said:
i wish i knew exactly where to grind and how much i wrecked a 402 head already grinding too much away
I think Bob is saying cut on the piston, not the head. Just off the top of my head, I can see myself using some slow-drying paint to paint the inside of the chamber, then bolt the head on with 2 or 3 bolts and no gasket. Bring the piston up until it hits and you will transfer a little of the wet paint to the piston and show you where to cut it. Keep cutting a little at a time and re-dressing the paint with a brush until you get clearance, then remove the paint from that chamber and go to the next one. That might sound like a stupid way, but it makes sense to me.
 

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Discussion Starter · #8 ·
re

i understand what your saying its just i wasted 2 sets of head gaskets now and didnt realize that such an exspensive set of pistons would need this ive had trw 11 to 1s and they didnt hit
Its just frusterating thought i would be frying tires by now
thanks for the info
 
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