I6 C4 rebuild for new 347?

[j-sizzle]

I am in the process of an I6 to V8 conversion. I have a FR 347 hooked up to the old C4. It ran fine for awhile, but then of course the tranny couldnt keep up with the motor. My question is: Can i simply get a C4 V8 rebuild kit and rebuild my old tranny? It sounds like i can but im not sure. Thanks for any advice.

 

[JC6715]

What's your HP level? That will determine the kind of "goodies" you need to upgrade in the rebuild...

 

[65fastbackresto]

I think you need the case fill tranny.

I had a pan fill and my tranny guy didnt wt to build it, said there was some advantage to the case fill, but I`m not sure what. Maybe some of these other guys can fill you in.

 

[j-sizzle]

i am at about 350 hp, and i know i need something mostly for "street use". i am not sure i know the diffrence between a case fill and pan fill tranny...
Thanks again

 

[10secgoal]

Some guy like the pan fill better, but there are tons of guys making tons of power with case fill. They are all the same tranny's except for a few hard parts, like the drums mainly. They need to hold more steels and clutches

 

[brianj5600]

The V8 kit will work, but you will need thinner pressure plates. Talk to Broader performance. They are semi-local, Weatherford I think. The 6 cyl C4 out of my car had 3 frictions in one of the drums. It appear to be identical to the V8 drum, but the pressure plate was .300" thick. Swapping it for a thinner one would give you room for 4 frictions. In the service manual it says to upgrade to 4 frictions is rebuilding a 6 cylinder C4, so it is possible you will have the right pressure plate. If you don't already have money sunk into a nice converter and shift kit I personally would get a 70+ which has a bigger input shaft and more options for the valvebody. If you have been eyeballing a nitrous kit the small input shaft will be iffy. The converter and valvebodies don't interchange though. Don't be afraid of C5's either. They have better oiling and it is likely to have 5 frictions in the forward drum. You will however need a C4 bell, which you already have, valvebody and torque converter.

 

[Decurion]

C5? I aint afraid of no stinkin Corvette!

Enlighten me on the advantages of the c5 trans. Ive heard of it, but thought it was just a later c4 with a lockup convertor. What cars did it come in?

 

[brianj5600]

The C5 is basically a C4 with a lock up TC. It came in most Fords from 1982-86that used a 3 speed auto. The cases have an E2 casting #. The VB has an extra circuit to control lock-up. The passages that lead to and from the cooler are larger and the #9 thrust washer has direct pressure lubrication. Enlarging the passage may be possible and drilling the case to feed the #9 thrust is a common, simple mod. The C5 pump also directs more fluid through the cooler. A C4 pump can be modified to do the same. I have 2 C5's and both came with 5 frictions in the forward drum.