390 w/open chamber heads

Treblig, RRR's point was that AFTER the overdrive, your final ratio would be 2.74 if you were running 4.10s out back. That's the beauty of OD, as it brings down the effective final drive. I don't know if I'd personally go with 4.10s, but 3.55s or 3.73s will make it a ton of fun to drive around town without revving high on the highway @ 70-75mph. 3.23s with no OD are still 3.23s, and flaring to how ever much your converter slips to...


Regarding the intake, a performer can be ported, but you're really limiting the breathing of the engine itself. The performer intake has a smaller volume in the runners to improve low engine speed port velocity and this is especially useful for 273s, and 318s--which is what that intake was designed for. You're planning to significantly increase your displacement and that intake isn't intended to feed that engine up to your max intended RPM, especially when coupled with a cam over 220* at 0.050"...an RPM intake would be light years better, and will actually allow the engine to breath better. I have an RPM intake on my bone stock 5.2 Magnum, and I experienced NO loss of low engine speed torque...and if that's the case with a stock 5.2, imagine what it can be with a correctly built 390...