390/auto trans questions [Archive]

racecartom

10-31-2014, 10:37 AM

I have a MK4 with a 302 that I want to pull and do a big horsepower rebuild next year. In the mean time I have a stout 390 I want to install but have a few questions/concerns. Will a C4 w/FE trans adapter hold up to over 400 ft lbs of torque? I'm told the T5 will not. Any A-frame or trans mount mods? I plan to do the swap with the body on. Any suggestions? Should I drop it in as a unit?
Any help/advice will be appreciated. Thanks, Racecartom

68GT500MAN

10-31-2014, 11:57 AM

It can be done, but, there will be a LOT of modifications needed to accomplish the swap. The first will be engine mounts, next transmission mount, then will come exhaust...not trying to discourage your idea, but it will be a lot of work including welding.
Doug

racecartom

10-31-2014, 01:32 PM

I'm aware of the all except the welding and the trans mnt. What requires welding and what mods are required for trans mnt?

racecartom

10-31-2014, 01:35 PM

One more thing. What adapter/converter/flex plate should I use?
Racecartom

CraigS

10-31-2014, 03:53 PM

Certainly you should do what you want to but...the idea of doing welding type mods to engine and trans mounts and then reversing those a year later seems a bit over the top. 302s are a dime per dozen so why not leave yours as-is and find another to build up the way you want. If you are doing much of a build the only thing you would use would be the block and stuff like the front cover etc.

riptide motorsport

10-31-2014, 10:14 PM

I agree with. Craig S....

skullandbones

11-01-2014, 04:53 PM

Tom,

That's way too much work for what you will be doing. It would be expeditious to spend some money on a Dart block and build a "bullet proof" 302 based engine (maybe 363 stroker) or get a 351 and build it to replace the 302. The advantage of the 351 is an automatic 50 cubes and stronger block with not too much investment. Also, no welding or other mods just an intake and a few other components.

Good luck,

WEK.

GT Trooper

11-13-2014, 07:32 PM

I have a MK4 with a 302 that I want to pull and do a big horsepower rebuild next year. In the mean time I have a stout 390 I want to install but have a few questions/concerns. Will a C4 w/FE trans adapter hold up to over 400 ft lbs of torque? I'm told the T5 will not. Any A-frame or trans mount mods? I plan to do the swap with the body on. Any suggestions? Should I drop it in as a unit?
Any help/advice will be appreciated. Thanks, Racecartom

I used a metal plate extended approx. three inches from the F5 trans mount bolted/welded. Not difficult at all. My engine however is a stroked 460.
35695