'42 flathead v8 - c4 setup

str8axle63

str8axle63

Member
I have a 42 ford flathead v8 I want to install a c4 trans. Any bell house on the market that you would recommend ? Anyone use another auto trans you like?
Thanks for your help
 
Flat-O-Matic is your best bet. I used one and so did a friend and they work well. Also good tech support. They are located in Salem, Oregon.
 
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Speedway has a complete conversion kit for a flat head V8-C4, including a rebuilt C-4 trans that has the required improvements.. One of Speedway's C-4 conversions is currently listed on eBay for $2,149.
You will have to convert your rear end over to an open drive line and parallel rear springs, Speedway has the conversion for an open drive line.
A friend of mine converted his '36 Ford 4dr sdn to a C-4 set up several years ago, a really neat set up. I have another friend that uses Ford C-4 transmissions behind Buick 320 CID straight 8 engines in lieu of the original Dyna-Flow.
A properly built up C-4 will handle 550 HP... This is a must do thing in order to work behind a flat head, it's not that they need the improvements to the C-4 for horse power, it's the other features, stall speed, etc., that are important.
 
Why do they need improvements? I was under the assumption that you could run a stock C4 behind a flathead.
 
I think he missed a "not" in his post before "a must do thing". Just a guess. If that's not correct, I would also want to know why.
 
Me too, I would think it would be a straight swap, but I don't know much about flatheads . Also the truck has a two speed rear. Will this be a problem? Also does anyone know the price of the flat o matic ? Their website does not have much info.
 
Their website says to call for pricing. 20 years ago, I purchased one from Flathead Jack and I believe it was $500.
 
str8axle63 said:
Me too, I would think it would be a straight swap, but I don't know much about flatheads . Also the truck has a two speed rear. Will this be a problem? Also does anyone know the price of the flat o matic ? Their website does not have much info.
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Your original comments to this topic made no mention about the C-4 application being in a "truck", especially a truck with a two-speed rear end.
I don't think a two-speed rear axle would work very well behind a C-4 automatic.
I have a lot of friends that are still living in the past, building/modifying vehicles using mismatched parts that they harvest from a wrecking yard. When I was a kid I did the same thing. As I got older, I got smarter, opting for newer better parts/repairs that I did not have to work on all the time.
I don't claim to be a mechanic, I deal with people that are mechanics, that have the expertise to correctly fix things. In the case of a C-4 trans, or any other older automatic, they all have their own built in problems that could use some up grades in order to work a little more efficiently, in it's new application.

Reading the Speedway add for a C-4 flat-head conversion I noted that the kit even includes a 12v modified starter.
 
blucar said:
Your original comments to this topic made no mention about the C-4 application being in a "truck", especially a truck with a two-speed rear end.
I don't think a two-speed rear axle would work very well behind a C-4 automatic.
I have a lot of friends that are still living in the past, building/modifying vehicles using mismatched parts that they harvest from a wrecking yard. When I was a kid I did the same thing. As I got older, I got smarter, opting for newer better parts/repairs that I did not have to work on all the time.
I don't claim to be a mechanic, I deal with people that are mechanics, that have the expertise to correctly fix things. In the case of a C-4 trans, or any other older automatic, they all have their own built in problems that could use some up grades in order to work a little more efficiently, in it's new application.

Reading the Speedway add for a C-4 flat-head conversion I noted that the kit even includes a 12v modified starter.
Click to expand...
This is both my first flathead and first 2 speed rear . So yes I should have been more clear. I put a c4 in my econoline when I built it, the motor is pushing 600 hp and its worked great in there. I was hoping it would also work with the flat head with way less hp. I know nothing about the 2 sp rear. I guess I need to do more homework
 
Is your "truck" a pickup or big truck? Is the 2 speed rear end a Columbia unit for a pickup or is it the big truck 2 speed rear?
 
I believe it would be considered a big truck. It is an original marmon herrington.
I just got it running after figuring out many electrical and fuel problems. I drove it for the first time and the transmission or the transfer case is making a serious noise and the truck has way to much tork . I was thinking I would take all the all wheel stuff out and hook up a c4 I have to try the rear end shifter and see maybe its in the low gear.
Im still feeling it out just thinking of different ways to go
 
If your '42 is a MH 4x4 it would be a shame to remove the 4x components, converting it to two wheel drive. The '42 MH 4x's are quite rare, and thereby would have significant value. A 2 speed rear differential in a 4x trk would be a very unusual option, I am not to sure just how it would work in four wheel drive, and if it would work at all.

If you have a C-4 in your Econoline that is pushing 600 hp, I'll bet that the trans has extensive modifications. I have been told that a good C-4, without modifications has become very pricey, just like the GM 2004R because of their adaptability behind large CID/HP engines.
If you are considering modifications to your truck, I would suggest putting the body on a late model chassis. You would still have an old looking truck with modern suspension, etc.
I recently did a conversion to a '64 pickup I have. I used a complete '98 chassis, eng/trans etc. Really made a nice unit, a pleasure to drive..
 
I know of two different flathead/c-4 cars and the owners both say: Lack luster performance due to small torque converter. m
 
blucar said:
If your '42 is a MH 4x4 it would be a shame to remove the 4x components, converting it to two wheel drive. The '42 MH 4x's are quite rare, and thereby would have significant value. A 2 speed rear differential in a 4x trk would be a very unusual option, I am not to sure just how it would work in four wheel drive, and if it would work at all.

If you have a C-4 in your Econoline that is pushing 600 hp, I'll bet that the trans has extensive modifications. I have been told that a good C-4, without modifications has become very pricey, just like the GM 2004R because of their adaptability behind large CID/HP engines.
If you are considering modifications to your truck, I would suggest putting the body on a late model chassis. You would still have an old looking truck with modern suspension, etc.
I recently did a conversion to a '64 pickup I have. I used a complete '98 chassis, eng/trans etc. Really made a nice unit, a pleasure to drive..
Click to expand...
If I did go with a different trans I will take the all wheel drive stuff out but keep it all. I wont do anything that would prevent it going back to stock im really just trying to figure out the best way to go. I still have a lot to figure out with the truck
 
I have the Flat-O adapter with the C4 I rebuilt with a shift kit. I find NO lack luster performance at all. The blown 276 probably helps. LOL Seriously, it has been a pleasure to drive and performs exceptionally well.
 

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Do they make a c-4 kit for an early engine, or does it have to go behind an 8BA engine? The Speedway kit would not work on an early engine, they specifically say "late" flathead.
 
flatjack9 said:
Do they make a c-4 kit for an early engine, or does it have to go behind an 8BA engine? The Speedway kit would not work on an early engine, they specifically say "late" flathead.
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I am quite sure that someone has an adapter for the EFV8 21/24 stud engines. I know that a friend of mine put a C-4 behind a '36 21 stud engine in his '36 3dr sdn. Since the early engines have a bell housing cast into the block, and the C-4's have a bell housing that is bolted to the trans case, the adapter is most likely a flat plate that bolts to the engine block and the trans.


mfirth' comment about his experience with a C-4 behind flat head engines is most likely the result of just what I made mention in my original contribution to this topic. A stock C-4 behind a flat head engine needs a lot of help to make it work correctly.
 
Just dreaming at this point but would u have to split the wishbones to install the speedway c4 kit in a 40 sedan with a 59ab flathead ? Thanks
 
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