351C Automatic Trans Info
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
351C = 1970/74 Ford/Merc Passenger Cars only. Depending on the application, could have a Ford 4 speed top loader, C4, C6 or FMX.
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Lead Driver
Joined: Dec 2012
Posts: 9,739
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From: Wentzville, MO
What's the * In front of the part number mean?
Laughing Gas
Joined: Dec 2012
Posts: 801
Likes: 7
From: Toledo, Ohio
It still has a relatively short stroke so isn't a low rpm engine. But your heads are the same as the stock M heads and your compression ratio should be the same as my 351M. Mine did fine with the ZF5 & 3.50 gears running 2000 at 70. So I think you'll be fine if you can get yours to about 2000 as well.
. With a 2.73 rear end, may be able to boost cruising MPG with C4 tranny by simply jetting the carb. primaries leaner/more correctly... prolly about #64 - #66 jets... stock/tighter torque converter can also help... do you know what stall RPMs your current converter is? Rev it up stopped in gear with foot firmly on brake for a second to see what it is, a (borrowed?) tach necessary for accuracy... hard to guess at real RPMs...
. Get engine/tranny cruising noise levels quieter with noise absorber/insulation on the floor/firewall under the carpeting... also, good rubber engine/tranny mounts and good rubber frame to body mounts give quietness and smoother cruising, 'quality' feel...
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Lead Driver
Joined: Dec 2012
Posts: 9,739
Likes: 823
From: Wentzville, MO
Still have the original question. What have others done to install a AOD on a 351C. I know it's been done just can't find the specifics.
I read some one used a C4 flex plate but I also read that that combo can fry the AOD.
Posting Guru
Joined: Jul 2007
Posts: 1,355
Likes: 1
I couldn't agree more, im in the process f installing one on my 400, the only difference is the bolt pattern, you could have your stock one drilled... Besides its a good idea to use yours, since your engine is probably balanced with it...
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Lead Driver
Joined: Dec 2012
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From: Wentzville, MO
Flex plates are relatively cheap. I'd pop for the "right one" if I knew what that would be. I've read that using some of the flex plates currently on 351Cs will damage the trans and DO NOT want to damage the Trans. I believe it's something to do with spacing between the Flex plate, torque converter and pressure on the trans oil pump which causes the Tranny to burn up.
I figured with several people doing this swap that it would be as simple as saying "use a FMX or C4 or C6 flex plate out of a ???? to ???? vehicle".
Yes, a 351C Flex plate is weighted at 28 oz imbalance with 164 teeth. Apparently depending on the application it came with all three transmissions. But NOT a AOD that I can find.
A small block, straight 6, V-6 or 4.6L (probably others) AOD/AODE/4R70W will bolt right up. JUST wanna get the right Flex plate
I figured with several people doing this swap that it would be as simple as saying "use a FMX or C4 or C6 flex plate out of a ???? to ???? vehicle".
Yes, a 351C Flex plate is weighted at 28 oz imbalance with 164 teeth. Apparently depending on the application it came with all three transmissions. But NOT a AOD that I can find.
A small block, straight 6, V-6 or 4.6L (probably others) AOD/AODE/4R70W will bolt right up. JUST wanna get the right Flex plate
Lead Driver
Joined: Jul 2011
Posts: 8,679
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From: On the Edge of the Desert
As far as I know you use the current flexplate you have on your C4.
I'm doing the same thing you are. AOD behind 2v 4barrel 351c in a truck. I am planning on changing to 3.89 rear gears, possibly 3.70s. But I run 31" tires.
We put a AOD behind a 4v 351c in a ranchero. Used the old c6 flexplate. It went together just fine. It hasn't been run yet though.
I'm doing the same thing you are. AOD behind 2v 4barrel 351c in a truck. I am planning on changing to 3.89 rear gears, possibly 3.70s. But I run 31" tires.
We put a AOD behind a 4v 351c in a ranchero. Used the old c6 flexplate. It went together just fine. It hasn't been run yet though.
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Lead Driver
Joined: Dec 2012
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From: Wentzville, MO
Seems to be a lot of mis information. Supposedly C6s and C4s have different torque converter bolt patterns.
I'll be glad to get to the bottom of this. I have both C4 and C6 (maybe even a FMX) flex plates. I just need to know which is the correct one for the retro fit.
I'll be glad to get to the bottom of this. I have both C4 and C6 (maybe even a FMX) flex plates. I just need to know which is the correct one for the retro fit.