[tom s]

You can play with all the things BUT IMO 215 pumping compression will be a issue.Putting a "bigger" cam can bleed off pumping compression but we put bigger cams in to make better cyc filling so what happens at 2500-3500?Been through this too many times.My 91 gas line in the sand is 190 MAX,180 better.Carry on.Tom

[Formulajones]

Originally Posted by tom s

You can play with all the things BUT IMO 215 pumping compression will be a issue.Putting a "bigger" cam can bleed off pumping compression but we put bigger cams in to make better cyc filling so what happens at 2500-3500?Been through this too many times.My 91 gas line in the sand is 190 MAX,180 better.Carry on.Tom

That's been my experience as well.

Really doesn't matter what the static compression ratio of the engine is at this point. It's the dynamic compression that's going to be the concern just as Tom mentioned. Simple compression test would give you some ideas, as in this case.

Every engine I've ever had that would pump 210-220 psi was a real bear to run on even 94 octane pump gas. I had to be spot on with timing and fuel, but even on hot summer days that wasn't enough.

More camshaft was the solution, and even though larger cams are better at cylinder filling, it happens higher up in the rpm range where the engine isn't loaded as much so detonation becomes less of an issue. It's down low, off idle, slow speed, where most of the pinging problems lie, and couple that with a heavy car that has no rear gear, tight converter, it just exaggerates the issue.

Personally, that is a very very tiny camshaft for a 400, probably more suited to a 9:1 engine and/or 350 cubic inch.