TH400 swap

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Nov 1, 2005 | 08:55 AM

Hvymtlc5

Thread Starter

Melting Slicks

Joined: Mar 2004

Posts: 3,472

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From: Lake Ozark, MO

TH400 swap

Is the TH400 a direct swap for the 350? By direct swap, I mean transmission length and bolt up to existing 350 frame pieces....understand that some of the linkage may need to be relocated or reworked. Car is a 78.

Nov 1, 2005 | 10:28 AM

SanDiegoPaul

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Joined: Sep 2002

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From: San Diego - Deep Within The State of CONFUSION!

Quote:

Originally Posted by Hvymtlc5

I have not done it in a C3, but I did swap out the Turbo 350 in my Nova for a 400 after blowing up two of them.

Careful - there's two Turbo 400's (long and short tailshaft) I had to look a lot to get a short tail section but there's a lot of them around nowadays.

Rear yoke is different and the mount is diff too, so you'll need a new crossmember.

A built 400 can handle a lot of power. After literally grenading planetaries in my Turbo 350 twice with that Nova, I drove it for 5 years afterwards with a Turbo 400.

Nov 1, 2005 | 10:37 AM

norvalwilhelm

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Joined: Nov 2000

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From: Waterloo ontario Canada

What is so wrong with a 350??? Built they can handle alot of power. Unless you are a serious racer just have the 350 built. They actually respond better then a 400 to a shift kit.
A 400 also eats about 35 more horse then a 350.
I know for all out racing/toughness a 400 is stronger but for the street the 350 with a shift kit is a very good transmission.

Nov 1, 2005 | 01:08 PM

Hvymtlc5

Thread Starter

Melting Slicks

Joined: Mar 2004

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From: Lake Ozark, MO

Thanks Norville...I didn't know that (about HP loss with 350 vs 400). Just thought the 454 would need more tranny to handle the expected torque.

Nov 1, 2005 | 01:11 PM

Hvymtlc5

Thread Starter

Melting Slicks

Joined: Mar 2004

Posts: 3,472

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From: Lake Ozark, MO

Thanks Norville...I didn't know that (about HP loss with 350 vs 400). Just thought the 454 would need more tranny to handle the expected torque (500 ftlb).

Nov 1, 2005 | 07:10 PM

67-73-76

Instructor

Joined: Dec 2004

Posts: 236

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From: Clearwater Florida

Here is a Link that may answer some of your questions.

http://www.tciauto.com/tech_info/trans_dims.htm

Although not a corvette, I recently swapped in a TH400 where a TH350 used to be in a 86 full size Silverado.

Besides the drive shaft length issue you will need to get a slip yoke that fits onto the TH400 tailshaft. The TH350 slip yoke won't fit on the TH400 talshaft.

Also keep in mind that Chevrolet always installed the TH400 behind big blocks from the factory. As far as I know you could not buy a big block equipped car or truck with a TH350 installed from the factory.

Nov 1, 2005 | 11:39 PM

jimtreber

Racer

Joined: Jul 2002

Posts: 275

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From: South Bend, Indiana

I did the TH350 to TH400 swap on my C3. Was way simpler than I expected. Rear mount located different but was not a big problem. Driveshaft was the same but used a different yoke.