351C - FMX to C4 swap??

[Stangfanatic98]

My buddy and I are swapping out his FMX tranny for a C4 to put on his 351C. I've got a few questions though.

With the transmission OFF, we were able to turn the motor over (by hand, using the crank pulley) quite easily. With the trans bolted ON, we now cannot turn it over. The odd thing is, the tailshaft of the trans still spins freely.. in all gears and neutral.

Does he need to purchase a different bellhousing in order to make this work? The torque converter is aftermarket and designed for the C4 specifically fyi.

Your input is GREATLY appreciated,
Pat

 

[GoinBroke]

The trans should lock the tail shaft in the in the "park" position when it is indexed and you hear the clicking sound. Did you hear the double click when you were installing the convertor to the tranny? If not it could be the pressure of the tranny against the flywheel or flexplate causing a binding force. Did the convertor spin freely when you installed the conv to plate bolts?

 

[bnickel]

most c4's use a 157 tooth flexplate and the fmx uses a 164 tooth flexplate. you need to find out if his c4 is for the 157t or 164t flexplate. i'm betting his is for the 157t flexplate.

 

[GrandeStang73]

This is my mustang we are talking about. The flex-plate is a 164-tooth plate with a Late model C-4 tranny. It is a pan-fill C-4. Bellhousing bolts directly to the 351C. I just need some installation directions please.

 

[bnickel]

This is my mustang we are talking about. The flex-plate is a 164-tooth plate with a Late model C-4 tranny. It is a pan-fill C-4. Bellhousing bolts directly to the 351C. I just need some installation directions please.

you need to find out if the bellhousing is for a 157T flexplate or a 164T. that's what i was trying to say. both will physically bolt to the engine.

 

[302 coupe]

pan fills just about always use a 164 tooth bell and flex, like 99% of the time. If its not turning, I would bet that the converter is not seated all the way, which puts everything in a bind. Also, IF the converter has a drain plug, make sure its properly aligned with its hole in the flexplate.

 

[GrandeStang73]

I put a quart of fluid in the converter and seated it on the front pump. I then put the tranny on and the studs on the converter didnt come through the flex-plate. I then took the converter off and bolted it to the flex-plate and put the tranny on top of the converter. I now cant turn the crank by hand. Is this okay? or was there a different converter for a pan-fill C-4 or different bellhousing?

 

[GrandeStang73]

I put a quart of fluid in the converter and seated it on the front pump. I then put the tranny on and the studs on the converter didnt come through the flex-plate. I then took the converter off and bolted it to the flex-plate and put the tranny on top of the converter. I now cant turn the crank by hand. Is this okay? or was there a different converter for a pan-fill C-4 or different bellhousing?

 

[bnickel]

I put a quart of fluid in the converter and seated it on the front pump. I then put the tranny on and the studs on the converter didnt come through the flex-plate. I then took the converter off and bolted it to the flex-plate and put the tranny on top of the converter. I now cant turn the crank by hand. Is this okay? or was there a different converter for a pan-fill C-4 or different bellhousing?

you have the convertor in a bind. you need to install the convertor into the trans and bolt it up like you did the first time. it's ok that the studs didn't protrude through the flexplate that just means the convertor was fully seated, all you needed to do was pull the convertor forward with a pry bar or something to get the studs through the flexplate. now you have to pull the tranny and start over and hope like hell you didn't screw up the front pump.

 

[GrandeStang73]

I just did some measurement look-ups and found my specs. I guess I was doing it right. The front pump will be alright, the tranny is supported so theres no play on any bending. Thanks alot, I'm kinda kicking my self from switching to a 351C BOSS motor and a heavy duty C-4..... So much work, hope its worth it!