[GT182]

Gotta agree with Chip and 1967Tempest.

I'm running on 87 octane with my 400 4bbl 4speed and 3.55s, with a CR of 9.5 to 1. No ping or any other problem..... well a small overheating issue tho but that's all and it's not the engine's fault per say. It's that water pump problem that a lot of us are having. Tho it stays cool so far with a 160 thermostat.

[ta man]

Everyone is talking about static compression..except for Cliff that mentioned a cam that was too good at filling a cylinder,everyone should really look at their cranking compression as one of the factors.My current engine is 180 to 185 psi and runs well on 87 octane with about 10.25 for static compression.

[screamingchief]

Originally Posted by ta man

Everyone is talking about static compression..except for Cliff that mentioned a cam that was too good at filling a cylinder,everyone should really look at their cranking compression as one of the factors.My current engine is 180 to 185 psi and runs well on 87 octane with about 10.25 for static compression.

The problem with that is the very next engine with exactly the same cranking compression and static CR might be a completely different story.

IIRC your using the KRE-D aluminum heads so that has significant affect on that deal,as does most everything else.

Comparing iron head combos and aluminum head combos in terms of static CR is pretty much comparing apples & oranges,especially when the aluminum heads in question have a far better & more modern combustion chamber design than the OE iron heads have.

There are plenty of combos out there that will barely pump 140 psi and they'll still rattle their brains out,and there are other combos out there pump out over 200 psi,and they dont have even a hint of rattle,so there is no easy answer as to what will always work perfectly,and what wont ever work well @ all.

Even when trying to copy other "known safe" combos the results can be a bit hit or miss for others who choose to try following that very same route.

All it takes is missing one or two (or more) key details that the other guy took care of without even giving it a second thought.

FWIW

Bret P.