'71 Service manual says 455s had an 11" clutch and 350 a 10.4" clutch from factory. Pricing clutch from TA Performance they told me to use the 10.4" with my 455, due to the Centeforce being much better than original, stock unit. Any input and/or recommendations from anyone on using the smaller clutch? It is, afterall, only a half-inch smaller diameter. Also, would it be worthwhile to run the Centerforce II as opposed to Centerforce I? As a guesstimate, with my upgrades, I've got 400HP and 500ft/lbs torque running in a 4500lb. Riv with a 2.93 posi rear.
I don't have the formula handy, but an extra .6" of friction surface is probably 5% more surface area. I vote for the 11", especially with all the torque. My car has the CenterForce II 11" clutch, pressure plate, and throw out bearing......Works great, and has low pedal pressure.
Mcleod makes a 12" that will fit the 11" bolt pattern, if desired. Ugh, 2.93 !! Your launching ratio will not be optimal. Expect to slip the clutch for a looooong way. I would not use the smaller one. What is your tranny first gear ratio ??
Only other available rear gear in the Riv's 9-3/8 diff was/is 3.42. Tough to find a set. I do like the highway cruise rpm of the 2.93 I now run a VP TH400 (2.48 1st) and the torque does its thing in the high stall mode. The BW ST10 I've got is a 2.64 1st. I realize it'll never run out like a mid-size with lower rear gears.
