Even if they did, the deck clearance (down the hole at TDC) would still have been about -.120 Do the math. True zero deck flat tops would yield a 10.5 to 1 ratio in a 400 with open chambered heads.

 

. Depends on the gasket thickness and cc's of the valve relief... I think the 1971 deck was supposed to be about .067"... using that and a steel shim (.025") head gasket (don't know what they used) I get about low 9's... assuming 5cc valve relief (may be more)... later engines add a dish to the piston, as well...


.

 

I'm using Tim's flat top pistons zero-decked with a .039" gasket and expect 10.5:1 - according to Tim.

 

The engine had been overhauled before I got it. I think it had fourty over pistons that were dished. The heads are off. I'll try to get a picture tonight.

 

I get 9.25 to 1 with those figures.

 

I know the OEM pistons would be junk, but I just wanted to see if the 1971 400 has flat tops like many people say. I have never actually seen a 1971 400 with flat top OEM pistons and there are no pics I have seen on the internet, so I was just curious if it's true or not.

 

. Haven't seen any disputes about the '71's having flat top pistons... everyone seems to agree on that... the '71 Ford 400 seems to be patterned after the '70 Chevy SBC 400 with both engines having nearly identical HP, torque, carb. size, and compression ratio spec.s... and both going to pot afterwards in later years... except Chevy started offering 4 bbl. carb.s later apparently for MPG and emissions reasons... (and maybe advertising reasons)

 

The one engine I have is a D1AE. It was overhauled and has dished pistons in in now. It was overhauled before I got it. I'll try to get pictures up. My first attempt was a fail.

 

400 pistons





D1AE 400

Here are picks from the engine. It had been overhauled.