which flexplate for C4 behind 351?

rpm4lalo · 12-05-2004, 07:42 PM

I have a 69 Fastback witha mid 80's 351 swapped in place of the 302. The flexplate that the 351 came with was too large in diameter to fit inside the C4's bellhousing. So I used an 81 and up 302 smaller flexplate which almost worked. The TC studs are sticking too far past the flexplate causing a clearance problem. What flexplate from what year and make should I ask for from local parts stor to makle this setup work.

I also am aware that the 351 requires 28.2 oz of unbalnce and the 81 and up 302 uses 50 oz of unbalnce, but I would be willing to get whatever flexplate rebalanced if it had the needed offset.

import slayer · 12-06-2004, 12:46 AM

If I remember correct I think I have a 164 tooth flywheel on my 351w with C-4.
It's either that or the 157 toothflywheel but I think I counted 164 teeth when I installed it.
I do know you need the 157 tooth wheel for the manual tranny that is hard to find and expensive.

69mach1377 · 12-06-2004, 01:26 AM

I think it would be the same for any early small block with the 28oz balance...find a used/older one instead of modifying a newer 50 ouncer.

rpm4lalo · 12-11-2004, 08:28 PM

I went and looked at alot of flywheels. And the none of them are right. I found out I need a 157 tooth flywheel which is smaller but the holes for the torque converter studs are too deep, they sit almost a full 1/2 inch different from the larger 351 flywheel. I am completely stumped. [&o]

roundman · 12-12-2004, 01:35 PM

contact one of the following auto tranny places and see what they say to help you.
www.lentechautomatics.com
www.tciauto.com