C6 to C4 conversion on my 428CJ

[jgkurz 52]

Hi All,

 

My Q code Mach 1 is in the process of getting an FE put back into the car. Today it has a 429 (385 series) with a C6. I want the car to look period correct but I'm fine with improvements that aren't super obvious and don't require the car to be hacked up.

 

I need to buy a new transmission for the FE anyways so I'm thinking a C4 might be a nice improvement over the C6. The car will be a cruiser and will be on the drag strip so the .2 ET improvement would be nice. Performance Automatic can build a strong FE C4 setup so that's not an issue.

 

What I'm not sure about is the shifter, trans mount, speedo cable, and driveline. Does anyone have experience or knowledge about this swap?

 

Thank you.

Edited October 5, 2014 by jgkurz

[Rsanter 152]

Speedo, trans mount and shifter is the same or at lease will work fine

 

Bob

[barnett468 418]

My Q code Mach 1 is in the process of getting an FE put back into the car.

 

I need to buy a new transmission for the FE anyways so I'm thinking a C4 might be a nice improvement over the C6.

hello;

 

i'm confused, how is a weaker trans going to be an improvement?

 

also, i'm curious as to how you plan to bolt the small block trans to the big block bolt pattern?

.

Edited October 6, 2014 by barnett468

[jmlay 80]

C4 consumes less HP & TQ, less parasitic loss. Built properly a C4 can withstand lots-o-HP/TQ. There are several companies selling an adapter plate as not to mention the complete bell-housing conversion, Performance Automotive, Quicktime, Profit, etc...

[sportsroof69 13]

A PA built C4 is better than any C6. It's far from a weaker transmission and will hold up fine.

[barnett468 418]

C4 consumes less HP & TQ, less parasitic loss. Built properly a C4 can withstand lots-o-HP/TQ.

thanks for that info and i am familiar with that and several also run the 2 speed turbo glide. i just wasn't aware you were that concerned about drag racing because you mentioned street along with some drag in your post although i could see die hard drag racers being concerned about saving .2. even though its a weaker trans you can still build them to be pretty strong. it only needs to be strong enough to hold up.

 

 

There are several companies selling an adapter plate as not to mention the complete bell-housing conversion, Performance Automotive, Quicktime, Profit, etc...

thanks for the info, did not know that. Edited October 6, 2014 by barnett468

[sportsroof69 13]

Intentions stated in the first post.

 

 

Hi All,

 

My Q code Mach 1 is in the process of getting an FE put back into the car. Today it has a 429 (385 series) with a C6. I want the car to look period correct but I'm fine with improvements that aren't super obvious and don't require the car to be hacked up.

 

I need to buy a new transmission for the FE anyways so I'm thinking a C4 might be a nice improvement over the C6. The car will be a cruiser and will be on the drag strip so the .2 ET improvement would be nice. Performance Automatic can build a strong FE C4 setup so that's not an issue.

 

What I'm not sure about is the shifter, trans mount, speedo cable, and driveline. Does anyone have experience or knowledge about this swap?

 

Thank you.

[jgkurz 52]

Thanks for the responses everyone. While researching the viability of a C4 I have learned that my new engine may not have enough vacuum to work properly with a modulator. According to the folks at Performance Automatic I need 15in of vacuum at idle to shift properly in drive. They said my only option is a manual valve body. It looks like a top loader is in my future....

[barnett468 418]

hello . the manual auto is still much easier to shift than a top loader though .. . if you go top loader i would use the big 10 spline . you will have to find the right tail housing then decide on the wide or close ratio. . i would also use the orig style 3 finger pressure plate . . mcleod sells then .. i would also reinforce the equalizer bar and run a needle bearing pedal pivot . .b i.

Edited October 7, 2014 by barnett468

[jgkurz 52]

hello . the manual auto is still much easier to shift than a top loader though .. . if you go top loader i would use the big 10 spline . you will have to find the right tail housing then decide on the wide or close ratio. . i would also use the orig style 3 finger pressure plate . . mcleod sells then .. i would also reinforce the equalizer bar and run a needle bearing pedal pivot . .b i.

 

Another option would be a TKO600. Modern Driveline makes a nice kit that has almost every conceivable part I'd need. Decisions decisions...

Edited October 7, 2014 by jgkurz

[barnett468 418]

Another option would be a TKO600. Modern Driveline makes a nice kit that has almost every conceivable part I'd need. Decisions decisions...

well...uh....yeah...i suppose that might work, lol. actually you will go slower with that trans because you have to shift more. the power of that big block will pull the 4 speed nicely, but if i had my choice i'd get the 600 if i did much fwy driving.

[jgkurz 52]

well...uh....yeah...i suppose that might work, lol. actually you will go slower with that trans because you have to shift more. the power of that big block will pull the 4 speed nicely, but if i had my choice i'd get the 600 if i did much fwy driving.

 

Go slower??? Not the way I shift : )

 

Thanks for the replies.

[barnett468 418]

Go slower??? Not the way I shift : )

 

Thanks for the replies.

must be nice to be young, lol. it would probably take me about 10 minutes nowadays to do the quarter in any car with a manual trans.

[390mach1 49]

Can you give me an actual website? I can't find these plates.

 

Thanks

[jgkurz 52]

I only know of the complete transmissions being offered by Performance Automatic.

 

http://www.performanceautomatic.com/products/street-smart-systems/ford-transmissions/c4-street-smart-systems.html