C4 identification

[buell-eyed-devil]

I bought a c4 auto for my 5.0 conversion. How do I tell what flywheel is compatible?

 

[buell-eyed-devil]

I meant flexplate

 

[adsm08]

Flywheel compatability to the bell housing will be determined by tooth count. A small bell C4 needs a 157 or 160 tooth, and big bell needs a 164 tooth.

Summit sells 157 and 164 tooth flex plates in both imbalances.

A 157 and a 160 are roughly interchangeable for size and starters.

 

[19Walt93]

There's a measurement from one bell housing bolt hole to the upper starter bolt on the opposite side that'll identify whether it's a 157 or a 164 tooth flex plate. If it measures 16 7/8" it's a 157, 17 5/16" is a 164. The Mustang II set up I'll be using in my truck has about a 140 tooth flywheel and a 10" convertor
with the mounting bolts 9 1/3" on center but they're getting scarce.

 

[buell-eyed-devil]

Flywheel compatability to the bell housing will be determined by tooth count. A small bell C4 needs a 157 or 160 tooth, and big bell needs a 164 tooth.

Summit sells 157 and 164 tooth flex plates in both imbalances.

A 157 and a 160 are roughly interchangeable for size and starters.

I have an 84 flat tappet block. How do I tell imbalance?

 

[buell-eyed-devil]

Looks like I have a 164. Probably have a couple flexplates for that

 

[19Walt93]

If it's an 84 it's a 50 oz/in imbalance. I think 81 or 82 was the cutoff, same year the one piece rear main seal appeared.
Earlier 302's, all 289's and all 351's are 28.2 oz.

 

[buell-eyed-devil]

Thank You