New Pistons Too Short.

[geoffinbc]

Well I just got a call from my machinist and was telling me that most aftermarket pistons which are stock replacement are usually about .020 shorter than the stock ones. I had asked them to zero deck the pistons to the block and he went and took .014 off the block so far but he does not think he should remove any more since he has removed the amount of material it would have taken to zero deck the original pistons. Removing more may lead to intake problems and so on.

I really wish manufacturers would disclose this info in their product listings its a real pain in the ass to find this stuff out after you get the parts that took a week to get in the first place.

My only concern now is that even though the pistons are shorter hopefully the dish is designed to maintain stock compression ratio. Has anyone else ever run into this?

[SappySE107]

Gectek told me his stock pistons were flush with the deck, so perhaps they were replacements? I haven't ran into this myself.

[geoffinbc]

Well I am ok with it as long as compression is ok and nothing else is causing this problem.

I cannot find the stock compression height on the site anywhere. But the Speed Pro Site lists 1.442" with a .105" dish for the pistons I bought p/n WH562CP 1.00MM

[BMC]

Too bad... I'm not sure about the 60 degree but other engines we have had, we want to have the piston come just above the top of the deck into the head gasket area with the center of the piston dished so the compression/fire will mainly take place in the center and move out from there. Basically, combustion in the head and centre of the piston away from the rings.

-BMC.

[geoffinbc]

Yea I wanted a zero deck to get the minimum spec for piston to head clearance. I will measure the stock pistons when I get them back and see if the new pistons have a lower compression height than the stock ones. If it is the same then I have the wrong pistons, again,(even though the p/n is correct) or something else is screwed up.

[ForcedFirebird]

That doesnt make sense, raising the quench to those measurements. That would give a stock rebuild on a 3.1/2.8etc .07", unless they consider a rebuild that needs .02" off the deck.

[geoffinbc]

Yea I know it pisses me off. It really is the only over the shelf piston available for the 3.1L Iron Head motor.