[Rafa]

Hi all.
Let me start with the basics: I'm restoring a 1970 Coupe, originally it was a 302 2V with a C4. The 302 is dead so I bought a complete 1985 5.0 for cheap with numbers on the valve cover sticker: E/J 304AA 12/3/85 +10. What do they mean? I know it is not a HO but my priority is to make it work. I have the original C4 transmission that was on the Mustang and was planning on using it with the 5.0, while doing eyeball mesurements and whatnot I found that the flexplate is different (old is smaller and converter won't bolt) and the old flexplate has counterweigths. Now, the 5.0 will be left with the FI and accesories, but what about the transmission? and what about the balancing of the rotating stuff? I'm a bow-tie guy going to the blue oval so any reference will help.

Thanks all,

Rafa

[EagleAutosports]

Hiya and welcome. Glad you joined us.
That C4 you have will work as long as you change the flexplate and make sure it matches the converter bolt pattern. There's a 164 tooth and a 157 tooth, you'll need it to have a 50 ounce balance for the harmonic balancer. Overall the 157 seems to be the better of the two but both are fine to use.

[Rafa]

Thanks for the welcome, glad to be here!The original flexplate is a 157 (smaller) than the one on the engine, and it has a huge counterweight on it. The one on the 5.0 has no counterweight but a cutout and it's bigger (164), so if I replace 164 flexplate with the old 157, it will match the TC (it was mated before) and the counterweight should be ok to keep things balanced.

Sorry for the extra question, but I want to make sure, I don't want to install/remove the tranny to reset the flexplate as I already have this experience with the swap I did years ago from a 4.3 to 305 (GM) swap.

Thanks.

Rafa