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Discussion Starter #1
Is it do-able? The tranny isn't in the best shape, but a mild rebuild'll do it real good. I know that I gotta replace the intermediate sprag with something a little more malleable. But how long will that tranny live with an open 3.55 rear and a 396/325hp from a 66 Impala? There's someone I've been talking to about buying the motor, and I can't pass up a complete carb to oil pan, detailed, 40,000 original miles Rat.

Thanks.

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Another poor college student trying
to keep another Chevelle on the streets.

--70 Malibu--
350/300hp (more than that now)
and a decaying TH350
 

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I don't know. That would depend on your driving habits. I know a TH350 can not handle as much torque as a TH400 or 700R4. But if your going with a stock engine and a better than stock tranny, you should not have any problems.

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JR
70 396SS El Camino #'s Matching.
69 396SS Chevelle, project "Street Bruiser"
H-D Ultra Classic E-Glide
I live to own toyz...


[This message has been edited by SS396ELKY (edited 12-13-99).]
 

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With a decent rebuild you should have no problems with a th350 behind a stock big block, you can get a throttle valve cable for it by ordering one for a 72 Nova with a 396 from GM.
I ran one in a 1974 GMC fulltime 4x4 with a 350 horse 402 BB for 17 years. I pulled trailers, hauled firewood and building material. Ran it hard and often, it had no external cooler and for 15 of those years with no TV cable. I sold the truck 3 years ago and the new owner is using it hard and it is still going. The truck has 300k on it, the engine has 200k and the trans milage is unknown.

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Philip Valentine
Lakeside, AZ
Member #42 GOLD
"Perseverance is not a long race; it is many short races one after another."
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Discussion Starter #4
If the general consensus is "go for it", than so it will be. This swap should be finished around May-June time. My baby's in storage now, so I can only dream and salivate over rats and such...
 

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I have done this many times when updating a small block car to big block. I always install a b/m transpak on street/strip level and have not blown one yet, and have run them on the dragstrip.

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70 chevelle ss396 conv
66 chevelle ss396 hdp/conv
55 chevy prostreet
 

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It's not quite the same, but I have a TH350 with the BM pack Drptp mentioned behind the 400 SB in my 69 pickup and I have had no problems. The engine is set up for towing (small heads, high torque cam) and the trans got the Street/Strip version of the shift improver kit (it allows for two or three versions to be done out of one kit: street/strip, towing, street/strip II) and I have had no problems. Once I got the kickdown cable set up it worked like a dream. Of course my motor is fresh as is the vacuum modulator on the trans. I didn't touch anything inside besides putting in the trans kit and it had at least 100k on it at the time.

I've pulled trailers, etc.: No problems so far.
 
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You're already been given some great answers, but I will give my comments anyways...

The TH350 will work fine for you. If you keep it cool with a tranny cooler, it'll live twice as long. Also, with the peg-leg, you won't be putting much load on your transmission...
 

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Discussion Starter #8
out of curiosity, what's a peg-leg? Are you talking about the open rear diff?
 

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If you can start with the truck 396 TH350 from the 70 thru 72 3/4 and 1 tons, you will have the basis for the best 350 you can get. The truck 396 TH350s had more of everything, clutch plates, sprague rollers and clutch hubs, etc. Simply stated, these truck 350s are much beefier than the car 350s, and are way less expensive. Same shift kits and converters for both trans types.

We still run one behind a fairly stout oval port 468, with three stage nitrous, on the street, and have not had any troubles for over 5 years the car has been together.

Do use a good trans cooler, spin-on trans fluid filter, and run the fluid through the regular radiator cooler before it goes through the air cooler and filter, then back into the trans.

The small-block TH350s in trucks are same as pass car uhnits, and need more to make them as strong as the truck trans' I mention.
 
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