[HO LEMANS]

Originally Posted by Formulas

An important part of your equation is compression ratio. if you have flat tops in a 428 and bleed down lifters under 16 heads you might create to much dynamic compression when at running temp.... the bleed downs on paper will give more low end torque yes but what else is going on then? a reduction of valve duration which is in effect a smaller cam at that time and if octane tolerance is low due to a higher static compression you can be shooting yourself in the foot

Formulas the pistons have not yet been purchased for this engine... I know I was reading some stuff on the necessary dish for the 428 pistons to get her just under 10 to 1 compression and was going to bore all you guys with that question earlier this morning but our internet was flaking out so I will do it now since you have already touched on the compression issues I may run in to. So any good info in that direction would be greatly apprectiated.
Thank You

[Jay S]

The old Crane Hi energy variable duration lifters do not generally affect the compression required for pump gas. If they do change it, it isn’t much. They usually do about 1/2 to 2/3 of what the original Rhoads would do.

The M20 with 3.55s usually can tolerate a good sized cam with most engines. Sometimes the power valve needs to be modified to eliminate off idle surging.