Power rating for stock TH350?

Discussion in 'The "Juice Box"' started by online170, Jun 30, 2006.

  1. online170

    online170 Well-Known Member

    Looking at purchasing a chev bolt patter TH350 rebuilt to stock specs, with roughly 5K miles. Its gonna be mated to a 463horse 350 motor with similar (if not more) torque. The car will be driven mostly on the street, will see the strip a few times, and my foot might slip a few times while cruising. Will the transmission stand up to the motor? What are the stock TH350's rated at?
     
  2. Nicholas Sloop

    Nicholas Sloop '08 GS Nats BSA runner up

    I wouldn't do it. I believe the highest torque the factory ever put through a TH350 was 410 ft/lbs
     
  3. online170

    online170 Well-Known Member

    Your right nick, i saw an article on hot rod the other day, saying that the stock rating hovers around 400 ft/lbs depending on vehicle weight, traction and rear gear ratio of the car. That motor would definately blow it.
     
  4. Ed O'Brien

    Ed O'Brien Member

    We run 350 trans in our 455 stocker and it runs in the 11s and weighs 3900lbs
    and it has not broke . Ed
     
  5. online170

    online170 Well-Known Member

    Wow, really? Is this a stock 350? I dont doubt that it can be built to take that power, but not without some modification.
     
  6. Ed O'Brien

    Ed O'Brien Member

    All hard parts are stock .Ed
     
  7. Nicholas Sloop

    Nicholas Sloop '08 GS Nats BSA runner up

    Yes, but the "rebuilt to stock specs" transmission in question here ain't gonna do it...
     
  8. D BERRY

    D BERRY 72 Skylark 2 DR POST

    You can always do what I'm doing, running that 350 turbo til it quits working, then put a good trans in it.My 350 has been behind my 455 for four years now, although I don't drive it much except to and from a dragstrip, so it gets abused. Even blew a u/joint last year but no troubles with the trans yet. :Do No:
     
  9. online170

    online170 Well-Known Member

    I might end up doing something like that. We'll see, hopefully the guy will throw in his built transmission with the deal for the motor. In which case i wont need to worry. Thanks for the replies.
     
  10. wilburdean

    wilburdean nameless stranger

    my best friend had a 69 chevy stepside pick-up we put a 454 in. the 454 had been built by someone who knew what they were doing and we were told it dyno'd at a tick over 500 hp. we went through 5 th 350's in that thing just thrashing it a little on the street. put a 4 speed muncie in it between autos as the truck was originally a 6 cyl/ 3 on the tree truck and already had the clutch pedal hung and everything. between th350# 4 and #5 my bubba snatched 3rd out of the muncie. i had located an 400 turbo but it had the long tailshaft and it wouldn't work with the current driveshaft. he bought 350 #5 and put it in rather than getting the stuff to make the 400 work. smoked #5 then put the muncie back in with the dead 3rd gear. temperary fix till we got the stuff together on the 400. well, truck got wrecked. bad. now there is a 454/400 turbo in his out building waiting for a home. i know every one of those th 350's were promised to "handle" that 454 and none made that promise good yet. i hope in the future we get to see if that 400 will. but in my honest opinion i won't have a 350 turbo in anything with that much power and torque. swappin slushboxes every weekend sux.
     
  11. SS-TRUCK

    SS-TRUCK Stage 1 X

    The 350 is a tough transmission when built right . A few yeas ago Randy New held the G/SA record in a 72 GS using a 350 transmission . I never saw him break a trans . I don't know his horsepower or torque but his 455 was making good power and lifting the front wheels every launch . I have a 71 Lark with 350 motor and 350 trans running 11.90s at 3900 lbs , only trans problem was bad torque converter .
     
  12. online170

    online170 Well-Known Member

    Youre right mike, it is a very tough transmission, but it would need slight modification to handle the 400+ ft/lbs. It doesnt take much, just a new valve body, a nicer shift kit, a trans cooler, and a few other external things can bring up the rating quite a bit. But for the really tough stuff, the clutches and wear parts shoudl be replaced with higher quality.
     
  13. SS-TRUCK

    SS-TRUCK Stage 1 X

    Online170 you are right it does need a few little things to take the abuse . Mine has a stock cooler , but the radiator is for a 455 used with a 350 motor , the clutches are upgraded as is valve body , but nothing big or expensive . My biggest fault was using an econo converter . had to learn the hard way .
     
  14. 69cloner

    69cloner MoparKilluh

    so if u have a convertor that keeps popping on ya most likely its a weak convertor not rated for your torque specs???
    ive just had a new beefy th350 installed and this is my 2nd convertor thats giving major leakage.. Im hoping this is all it is..just teh convertor like last time. would upping the size keep this from happening?
     
  15. SS-TRUCK

    SS-TRUCK Stage 1 X

    I only broke ONE converter , an econo type , then I spent money to get a good one and never the slightest problem . You get what you pay for , I paid for a cheap converter once , now I paid for a good one and got it .
     
  16. My69GS350

    My69GS350 Well-Known Member

    ???? 400 flbs of torque on a turbo 350? A stock 1970 GS 350 puts out 400 + pounds of torque I think?

    Mark
     
  17. Nicholas Sloop

    Nicholas Sloop '08 GS Nats BSA runner up

    I do believe the stock 70 GS 350 motor is 410 ft/lbs
     
  18. Jeff Hart

    Jeff Hart Platinum Level Contributor

    Hmm. I know of two Buicks that run in the mid to low nines at 3600lbs. with a Turbo 350. Do the math
     
  19. SS-TRUCK

    SS-TRUCK Stage 1 X

    As I said before and will say again I like the 350 transmission. When built right they are tough , much lighter than a 400 and take less horsepower to turn them. So for my money I will stay with what is working for me and not try and reinvent the wheel. Anybody ever use a transbrake on a 350 ? I am wanting to try that and just curious how well it works .
     
  20. 76century

    76century Well-Known Member

    1970 GS 350 with high output option made 315 horsepower and 410 ft lbs torque. Good for stock, and just throw a few mods on to make it just a bit better and it would be pushing well over those numbers. So stock TH-350s are tough transmissions. Not quite as strong/durable as a TH-400 in stock trim, but when built right, as mentioned, is definetly a strong/and reliable trans. behind almost any high performance application. Just some research/studying that I did, and those are conclusions I have come to. :Do No: :TU:
     

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