1951 flathead to C4 conversion
 

I have a 1951 Vicky. I would like to convert the flathead to C4 automatic from a 1965 Falcon. I have been searching for an adapter kit, but they seem to be non-existent any more. What would I need to make the conversion?

Any help would be appreciated.

Re: 1951 flathead to C4 conversion
 

Flat-O-Matic Products

Bendtsen's Transmission

Re: 1951 flathead to C4 conversion
 

Also H&H Flatheads

Re: 1951 flathead to C4 conversion
 

I used a Flat-o adaptor in my '55 with a y-block. Most everything you need in the kit. I think I would look for a later C-4 than a '65 tho. Perhaps '70 on up. JMO.

https://flat-o.com/carproducts/flatomatic.htm

I believe the kit H&H sells is from Flat-o.

Wilcap also makes Flathead adaptors but I think they are for mating a GM auto to the V-8.

http://wilcap.com/

Re: 1951 flathead to C4 conversion
 

The C-4's have become very popular behind many engines, I know a man that uses them behind big Buick straight 8' 320 Cid with over 500 HP. The C-4's need some improvements, as do the GM 2004R.. Several years ago it was very difficult to give a C-4/2004R away, now they are like gold.

Re: 1951 flathead to C4 conversion
 

Check out moderndriveline.com they might have what you’re looking for.

Re: 1951 flathead to C4 conversion
 

Speedway Motors has a C4 to flathead kit, with or without the trans.

Re: 1951 flathead to C4 conversion
 

Based on an article on mustangsansfords.com the best C4's are 1970 and newer because of the larger input shaft.



I have used a 1980 in my Tbird (behind a YBlock). Flat-O kit. In my 48 Ford with a 302 and C4, the trans is a 1968 model that has served me well over a long period of time so the earlier ones are still very usable.



Based on my experience, if you are going to have a floor shift the gear selector on the trans should point up, if a column shift it should point down. I think the gear selectors are available if you do not have the one for your application. I know one person that did the switch modified the gear selector to work (floor with with a downward selector).



As far as cooling, I use an inline cooler rather than run through the radiator. Seems to work very good.



The neutral safety switch is bolted to the trans and seem to be readily available the last time I checked (which was some time ago). The switch is also available from Ron Francis which makes and sells wiring kits.


If you buy a kit, check with the vendor on which C4 goes the best with his kit.

Re: 1951 flathead to C4 conversion
 

Thanks, everyone. I tried all of the places mentioned; no one has the kit for a 65 C4. I already have the tranny, and I've used them before with good results. Would like to use it again.

Re: 1951 flathead to C4 conversion
 

Speedway shows online this one in stock.

https://www.speedwaymotors.com/Searc...ion%20adapters

Re: 1951 flathead to C4 conversion
 

Your problem is that the 65 has a 5 bolt bellhousing, 66 and later all had six bolt.

Re: 1951 flathead to C4 conversion
 

The C4 needs a lower rear eng gear ratio 2.9/350 depending on engine mods and location. i used a 3.3 from the stock Ford o matic rear. You might consider an AOD which has an OD and works quite well when prperly setup.
Gramps

Re: 1951 flathead to C4 conversion
 

To my way of thinking, if you are going to spend the time and money to do a modification to a vehicle, the modification should be done to a high standard.
I have AOD transmissions in three of my vintage vehicles, '39 Plym, '37 GMC and a '49 Olds 88. I spent the first ten years I owned my '36 Ford, improving the mechanical components for safety/comfort and drivability, without changing the look of the car.
My '36 came with a Columbia, I modified it using mostly '48 Columbia components mated to the '36 torque tube and '37 radius bars.