Stupid, quick piston/block question.

[86Shelby]

Quick question. The piston top while at TDC is supposed to be below the deck surface, right? This is on a TIII BTW.

I think I've got an issue since one is sitting about .010-.020(rough eyeball measurement) above the deck at TDC.

[Orangetona]

Im going to go check for you right now.

Edit: On my 2.5 its almost perfectly flush with the deck. If its not its a hair under it.

[turbovanman²]

Flush with the block, but some sit slightly under, like a C hair, :p

[86Shelby]

Red or blonde?

[turbovanman²]

Red or blonde?

Red, :nod:

[Lotashelbys]

I have had a few stock ones(never been apart from factory)that have been up a thou or two but not any more than that. Have you ran this motor yet?

[Devsdaytona]

Hope your head gasket is thick enough:p

[86Shelby]

I have had a few stock ones(never been apart from factory)that have been up a thou or two but not any more than that. Have you ran this motor yet?

No, it hasn't been run so far like this. Basically it's a re-ring & bearing overhaul. Deck the block, clean-up hone on the cylinders, resize rods & ARP bolts. It was a bone stock, never been touched block.

I'll be running the thicker Cometic gasket since the head has been surfaced at least twice that I know of. Combined with the deck being surfaced I believe the CR will be higher than stock, even with the thicker gasket.

I'll have more info tomorrow about the rest of the pistons & how they sit in the block.

[Lotashelbys]

I'll be running the thicker Cometic gasket since the head has been surfaced at least twice that I know of. Combined with the deck being surfaced I believe the CR will be higher than stock, even with the thicker gasket.


I really think they need to offer thicker Cometics for us also. With your head being cut on more than once what is the distance between the VC surface and the HG surface? If you take too much off remember you move the cam timing. Both cams will be more retarded and might hurt you in low end. Unless you have adj. gears and can get the centerlines back where they need to be. I am driving one now that was like down to 4.99" and it has a stock thinkness(actually and 8valve HG with extra holes drilled)in it and I can tell the cam timing is off just by the way it runs.

[86Shelby]

Adjustable gears, no worry there.

What is the distance on an uncut head? Mine is measuring 5.004".

The piston is .02" +-.002" above the deck. It was tough getting repeatable measurements within that window.

[Lotashelbys]

What is the distance on an uncut head? Mine is measuring 5.004".
A new one is like 5.024 to .021 if I remember correctly. So if you got an .074 Cometic I wouldnt be too worried about it.

Did you say you decked the block too? How much is missing there?

[86Shelby]

I honestly can't remember how much the deck was milled.