Please Help!!!!
Thread Starter
Intermediate
Joined: Feb 2005
Posts: 43
Likes: 0
From: Rapid City South Dakota
Please Help!!!!
Hello,
I own a 1974 Corvette that originally came with a small block. When I bought the car, the motor had already been replaced with a run of the mill 350 out of a 72 Chevy pickup. I sold that motor for what I could and I am currently having a 427 built. I know I could get a lot of horsepower for not a lot of money out of a small block, but I’ve always wanted a BB Vette. I do have basic mechanic skills and would consider myself a novice mechanic. My questions are: What can I do to start preparing my Vette for this BB? I assume I will need new springs in the front. Will I need to do any modification to the engine compartment (I wouldn’t think so since some 74 models came with a big block)? I’ve been told the motor mounts for a SB & BB are the same…is this true? What about exhaust? I’ve read some of the postings on this forum and it seems that Stahl headers are the way to go if you want side pipes. Any Tranny tips? And how about axle ratio? The stock 3:08 setup is just too long legged for my liking. I also need new brakes. Any help would be greatly appreciated. Thanks,
BB74
I own a 1974 Corvette that originally came with a small block. When I bought the car, the motor had already been replaced with a run of the mill 350 out of a 72 Chevy pickup. I sold that motor for what I could and I am currently having a 427 built. I know I could get a lot of horsepower for not a lot of money out of a small block, but I’ve always wanted a BB Vette. I do have basic mechanic skills and would consider myself a novice mechanic. My questions are: What can I do to start preparing my Vette for this BB? I assume I will need new springs in the front. Will I need to do any modification to the engine compartment (I wouldn’t think so since some 74 models came with a big block)? I’ve been told the motor mounts for a SB & BB are the same…is this true? What about exhaust? I’ve read some of the postings on this forum and it seems that Stahl headers are the way to go if you want side pipes. Any Tranny tips? And how about axle ratio? The stock 3:08 setup is just too long legged for my liking. I also need new brakes. Any help would be greatly appreciated. Thanks,
BB74
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Motor mounts are the same. You'll probably need completely different pulley setup for power steering and A/C if you have it. The exhaust will need to be changed, but it sounds like you're into that already. You'll need a bigger radiator for the BB. Brakes should be fine, but it also sounds like you are fixing those. Internally, tach might need a different redline if that's important. You will also need a different console plaque! 
Pro
Joined: Nov 2004
Posts: 531
Likes: 118
From: Atlanta area
No mods to the engine compartment, as you thought, but you'll need different brackets for the alternator, PS pump, AC compressor, and an idler for the water pump belt. All this is available from Paragon or Corvette Central. Also, the small block AC compressor hoses won't work on a BB but the BB hoses aren't available. You'll have to have them custom made.
You might think about some added insulation under the carpet, too. The heat from a BB, especially with headers, can be horrendous.
You might think about some added insulation under the carpet, too. The heat from a BB, especially with headers, can be horrendous.
Melting Slicks
Joined: Jul 2002
Posts: 3,128
Likes: 3
From: Deltona (son of Deland and DAYTONA) FL
depending on the tranny and stall speed for the converter you choose. 3.08 gear might not be bad because of all the low end torque of the BB.
Bowtie overdrives makes some nice 200r4's if you're looking for an automatic.
Bowtie overdrives makes some nice 200r4's if you're looking for an automatic.
Melting Slicks
Joined: Dec 2004
Posts: 2,161
Likes: 0
From: pr, frederick md.
to each his own, but dont give up on those 3.08's so fast. when your turning alot of rpm's with 4.11's and the kid in the honda passes you because you cant go over 65 for fear of blowing your engine. youll wish for those 3.08's! unless you get an overdrive tranny, then forget i said anything
Thread Starter
Intermediate
Joined: Feb 2005
Posts: 43
Likes: 0
From: Rapid City South Dakota
Wow....
Wow guys,
Thanks for all the great tips. So if I'm going with a beefed up TH400 tranny, 3:08s might be the ticket? I'm sure I'll be back with plenty of questions.
Thanks for all the great tips. So if I'm going with a beefed up TH400 tranny, 3:08s might be the ticket? I'm sure I'll be back with plenty of questions.
