74 big block drivetrain
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
I ran a BB427 (400hp) in my 74 with the stock 350 power train but mine was a 4spd. with no problems. My Cutlass had a 455 with the th350 and it lived for a while. About 20,000 *** thrashed miles before the torque converter blew...
Team Owner
Joined: Jul 2004
Posts: 40,448
Likes: 793
From: Redondo Beach, California
This question has been discussed before in previous threads.
My old brain remembers that with an automatic, street tires - no more than 10 inch treads for sure, you could go with 600 to 650hp. I think I can remember the 650 hp figure being quoted by Tom of Tom's Differential.
Remember that the L88's (67-69) had 550 hp, manual transmissions, and the rear ends- same as production cars differentials, BB u-joints, BB-half axles, etc would hold up under road races.
There's a lot of improvements in C3 rear end's that are now available. Since it's pretty expensive to blow up a rear end, it would be prudent to upgrade it with improvements today even if you're only planning on 500 hp. There are some relatively inexpensive (!) things that will upgrade the strength of you rear end. Van Steel is a forum sponsor that will know what to do. Also, Tom at Tom's Differential. Tom no longer rebuilds units, but only sell parts many of which are custom made by OEM manufacturers just for him. Tom is a good source of advice although be forewarned he likes to keep conversations short.
My old brain remembers that with an automatic, street tires - no more than 10 inch treads for sure, you could go with 600 to 650hp. I think I can remember the 650 hp figure being quoted by Tom of Tom's Differential.
Remember that the L88's (67-69) had 550 hp, manual transmissions, and the rear ends- same as production cars differentials, BB u-joints, BB-half axles, etc would hold up under road races.
There's a lot of improvements in C3 rear end's that are now available. Since it's pretty expensive to blow up a rear end, it would be prudent to upgrade it with improvements today even if you're only planning on 500 hp. There are some relatively inexpensive (!) things that will upgrade the strength of you rear end. Van Steel is a forum sponsor that will know what to do. Also, Tom at Tom's Differential. Tom no longer rebuilds units, but only sell parts many of which are custom made by OEM manufacturers just for him. Tom is a good source of advice although be forewarned he likes to keep conversations short.
