SuperFast80

I am worried about the 454 blowing away the TH350 in due time. I am trying to build 500 GROSS hp and 400 NET.

The tranny is 22 years old and never rebuilt. It has ~125K miles on it and about 20K miles ago I put in a B&M kit.

Any ideas?


[Modified by SuperFast80, 2:49 PM 12/4/2001]

Stingy74

Everybody will tell you to run a TH400 but I feel the 20-30 horse (or so I am told) loss in a 400 tranny is substantial. Back in the day a friend of mine ran SuperGas in a Vega (9.90 index) he built and he used a TH350 with a 6000 stall. He has told me that to his knowledge that tranny is still in use somewhere and that's well over 10 years. I think if you build it right it will last a long time in street use. Just remember to use a cooler.

Golden80

I'm pretty sure it's all a matter of how lead-footed you are. If you don't nail it everytime it'll probably last a while. But wait for other opinions before taking my advice because I'm not 100% sure of it. I'd think you could probably get the TH350 built for it.

Matt

78RedShark

Oh, I can personally vouch that he nails it EVERYTIME :smash: ...there's just no other way...right Superfast?

45ACP

HP does not matter when it comes to trannies, rear ends, etc - they are rated by the amount of TORQUE they can handle.

The number that I have always heard that a stock THM350 can take day-in day-out is 400ft-lbs of torque.

From what I have seen this seems like a credible number BUT, I do not have a source to back it up, so don't bet the farm on it.

SuperFast80

400lb/ft NET or GROSS beacuse this thing is going to be around 500 GROSS.

Yes, I nail it ALL THE TIME, but my slightly balded 255s will stay on so the weak point will be traction and hopefully not driveline.

L71

I pulled a sweet turbo 400 out of my 69 camaro and went to the original Muncie setup , what a diappointment, I'm thinking about putting it back in

SuperFast80

What was disappointing? What was it? M-21?

TH400 is a bit stronger than TH350 right? I believe it also has a little longer gearing in 1st and 2nd too.

L71

My M21 is OK but nothing beats a 400 with a high stall, WOW

redc3vette1

hey SUPERFAST i would stay with the TH350 I think it will hold up just fine and its also lil lighter than the TH400 hey do you have a pic of that shifter in your car thinking of doing it to mine i just wonder if it looks good and how hard it was to put in and what kind did you use in yours? :cheers: :cheers:

L71

yes a turbo 350 is lighter but so is a 2 bolt main engine block

Techno

My understanding was the later models have a lighter drive train completely. Since the engines were enemic there was no reason to make them strong enough to handle large amounts of HP. I would think this would be a prime candidate for production cost slashing. During the double blow of emissions and economy during the '70s All the companies were scrambling.

If this is true it isn't your tranny thats the problem but the dangerous whipping of the drive shaft and half axles.

bence13_33

I don't think he has to worry about busting a driveshaft or a halfshaft. A u-joint will go long before he ever busts one of those. If I remember correctly he will be running 255/60/15 street tires, if this is the case he will never hook hard enough to have to worry about this.