c4 internals, how strong
 

I found a c4 for sale that is freshly rebuilt. Would the stock internals be ideal for a 10 second car ? I am planning on adding a transbrake and a reverse manual valve body. I know that imput shafts and whatnot are usually replaced aswell, im just wondering, can I get by with stock internals except the above mods ?
Please advise. thanks

My thought is that a stock C-4 will not stand up to a car running in the 10's. That much power (400-500 hp) will fry the clutches in a stock C-4. You will probably also be running a high (4000-4500) stall converter in a car like that. You'll need a built C-4 or C-6 for that application. Anyone disagree?

Rev

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

Agree. Also I think you'd need the heavy duty planetary - that's the weakest part of a stock C4.