How Good is Turbo 350?

[Roachgod]

My 1970 truck had a 350ci w/ th350 , i'm putting a new 454 instead. Do you think a th350 will hold up? Here's what's in my motor
454 from chevy 1 ton
9 to 1 compression
balanced lower end
crane roller rockers
new bigger pushrods and guides
new valves
comp cams with .504in lift .510ex lift
performer 2 intake
750 performer carb
new hei distributor w/50k coil
msd 6al
msd 8.5 mm wires
holley mech fuel pump 110 gph

any guesses what this could be putting out? I've been told about 425hp but i don't really know anything except it's pretty fast in the 1 ton when you ain't shifting that granny 4spd. I have a good th400 is it worth the trouble to make it fit?

[Green Machine]

Used or stock = not very long, properly rebuilt with HD components = pretty good, best = TH400 properly built.

[Robznob11]

put a 127.00 dollar bm kit in it and throw what ever you want at it. get them at jegs or summit

[Roachgod]

The th350 is used and i'm pretty sure it's stock. I have a th400 that I know was running 1 1/2 years ago and has been stored inside my home. I was scared to change too much on this poor old truck at once. I'm sorry for buggin everyone all at once but I just found this forum and it's a goldmine of info. I thought the hard part was buying that big pretty motor, but it seems that may have been the easy part. I should have known better. I guess they say good things come to those who wait.

[ThatOneBlue67]

In the past, I had noticed that big blocks usually came with a 400 instead fo the 350, like it's built to withstand the abuse from a big block. And I'm sure it would handle it pretty well as long as you don't floor it too much

IF you want to floor it, a lot, then TH400 is the way to go.

[ol yellow 72]

i have a turbo 350 behind my 454 with no problems at all, id say im putting out 370 h.p and i have a stock 350 turbo, with a small shift kit ands it s held up to my abuse well

[vtblazer]

I had a built th-350 behing a 396 that did great in my K20.

Did a fair amount of towing with it too. Gotta build the th-350 though.

[Huck]

Turbo 350 is an excellent transmission but the 400 is even better for high torque. Why not just use the turbo350 for now and if it goes kaka, get the 400 ready to go in. This way you don't invest in the 350 unless you need to and have a plan B!! Guess I'm cheap but I would much rather put money into an overdrive transmission before I put it into either 3speed.

[Robznob11]

well it all depends what you want stock yea the 400 is stouter. but i like to go fast, the 350 is lighter, and mildly but will handle the abuse. not to mention there is less rpm drop during shift changes witch means faster down the track and oh another thing you can put a 350 in any gear and keep it there where as the 400 is known for jumping up to the next gear. just some thoughts. the only problem i had with a 350 was in a chevy luv. the motor did not have solid mounts to keep if from twisting i was running a sb chevy 399 stroker with a 200 shot. it ran about a 10---- . when i plugged 2nd one time the motor twisted and shattered the out side of the tranny. all i have ever run was 350's with that cheap old 127.0 kit an im talking a th350 out of the bone yard as long as the pump is good thats all im relly concerned about. i throw 600 hp at them all the time

[1970 CST Short Wide]

I have a 350 behind my 454 with about the same specs as yours. Its holding up fine so far.

Off topic - When you get that BB running I'd like to know what you think of the cam

[Robznob11]

well it all depends what you want stock yea the 400 is stouter. but i like to go fast, the 350 is lighter, and mildly but will handle the abuse. not to mention there is less rpm drop during shift changes witch means faster down the track and oh another thing you can put a 350 in any gear and keep it there where as the 400 is known for jumping up to the next gear. just some thoughts. the only problem i had with a 350 was in a chevy luv. the motor did not have solid mounts to keep if from twisting i was running a sb chevy 399 stroker with a 200 shot. it ran about a 10---- . when i plugged 2nd one time the motor twisted and shattered the out side of the tranny. all i have ever run was 350's with that cheap old 127.0 kit an im talking a th350 out of the bone yard as long as the pump is good thats all im relly concerned about. i throw 600 hp at them all the time

[special-K]

I believe a TH350 can take anything a TH400 can.That`s been my experience.They need to be set-up for whatcu got and how you use it.I had one built for my`71 Blazer by a guy that was recommended by Dave Coleman,a leading race motor builder.Well,it lasted about 1,000 miles behind my 400 hp 350.Then,a guy that "REALLY" knew his stuff built it.His guy had it torn down,looking at roached clutches in 15 minutes while he talked to me.The trans was set-up for a 1/4 mile Camaro,not a 5,000# mud truck with 4 wheel posi and 37" SuperSwampers.He said he won`t build a trans w/o replacing the torque converter,most bad transmissions are caused by the tq-conv.There is no way to tell a good one from a bad one looking at it.I prefer the higher first to second shift-point of the TH350 and only use a TH400 for heavy duty applications.I`d rather use either 3spd and a GearVendors o/d than any o/d automatic.