quote:
Originally posted by SteveBuchanan:
... It may be as high as 11.8 ... he said ... this motor was probably built at a time when high octane gas was readily available ...
The tech at Clay Smith must have been a young guy. Pump gas like that wasn't available when the 351C was new.
I'm pretty certain the piston domes are the standard Ross pop-ups for the 351C. The piston specs are listed on their web site. They are definitely the wrong choice to combine with D0AE heads and pump gas.
With D0AE heads, a flat top piston with the stock 1.65 pin height will give you 10:1 static compression. This is assuming the engine has a stock 3.50 stroke crankshaft. Combined with an intake valve closing around 70 degrees ABDC that nets 7.7:1 dynamic compression, the car will run on 91 octane pump gas reliably. You won't need a dished piston. You can take the dynamic compression up to 8:1, but I like to leave a little wiggle room. The cam's intake valve closes around 72 degrees based on the spec card.
I always recommend a round skirt piston, due to the thin cylinder walls of the 351C block, but the Ross flat top has a 1.668 pin height. The pin height of the good ol' TRW flat tops is 1.647, that would be a good match with the D0AE heads. I promise not to tell anyone if you were to make that choice.
That cam has 76 degrees overlap, based on advertised duration. The engine will be a lot more street-able with about 60 degrees overlap.
Flat top pistons and a cam swap are my recommendation.
I was tickled to learn that Clay Smith Cams is still in business.