Is this a c4 or c6?



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The three-speed C4 Ford transmission can be differentiated from the C6 (also a three-speed) by its smaller size and thin, almost cylindrical case. There are two versions of the C4, a flare case and a step case. The flare-cased C4 tranny’s bellhousing bolts directly to the transmission case with five bolts, and the oil-pump bolts are separate. The case flares out to meet the bellhousing. The step case uses the same bolts for the oil pump and the bellhousing, and there’s a ¼-inch gap between the case and the bellhousing. Also, there’s no drain plug in the oil pan. The C5 looks identical to the C4, but the oil pan has a hump, versus the C4’s flat pan. The AOD (automatic overdrive) four-speed looks nothing like the C4, C5, or C6

 

The quickest way to differentiate between them is to look at the fluid pan. The C4 is square, and the C6 looks like an outline of the state of Utah. Also, the C4 bellhousing bolts to the transmission and the C6 is part of the case. No bolts.
So, what you have here is a C4.

 

So how does one bolt a C6 to a 302/289?
Jim

 

I have no idea. I suppose you could shop around for a kit, but the C6's were for large block cars and trucks, and like 1970 and up Mustangs. Here is something I found entertaining This company lists a C6 for 1970 and up 289's.
http://www.bmracing.com/media/catalog/6.pdf

 

You bolt a C6 up to a 302 by the 6 bellhousing bolts. Then, bolt the torque converter up to the flexplate.

Yeah, same way you bolt a C4 up to a 302.[&:]

Ford made quite a few C6's to go behind 302's (351W usually). I have a couple of 'em, but just don't have a place to use 'em yet.

 

So the automatic transmissionto engine bolt up pattern on a 289/302/351 is the same dimensionally as a 390/428/429? As is the flexplate to torque converter?
Incidental to this, I always identified a C6 by the fixed bell housing and a C4 by the removable one. (FMX is a cast iron case vs alumunum for C4 & C6.)

 

Yeah, like I said above, the C6 is a fixed bell housing and the C4 is bolted on.

 

Glen, I restore, I don't make a habit of changing camshafts daily, so a transmission swap takinga C6 and putting it into a C4 size engine is something I don't usually get involved with. I've read other postings and there were mentions of swaps of that nature. A C6 is larger, so it may not fit the tunnel in any case, so my question is more curosity than to do an actual swap. So back to the original question, are the transmission to engine bolt patterns the same on a 289/302/351 as a 390/428 etc?
Jim

 

I don't know Jim. I have never made that swap. I just read what others have done with this swap.