Which Flexplate?

[jimmycuda71]

I have a 496 based on a 440 block. It has a forged 8- Bolt steel crank, unsure of brand. I ordered a Mopar Performance flexplate for an 440 with an 8-Bolt crank. The center hole on the flexplate is to small to fit over the crank flange. Also the bolt holes do not line up and I tried rotating it to all 8 positions and the holes never lined up perfectly. Any suggestions on what I have, or need to order.?

[dfrazz]

Is it internal or external balanced?  Does the plate match?

[jimmycuda71]

Internally balanced.   After getting 8  bolts instead of using 2 and eyeballing the holes. The  bolt holes do line up. After I checked the crank and  flexplate with a mic. The hole in  the  flexplate is .017 too small. So should
I just ream the hole a little bit and  go on?

[Chryco Psycho]

The Hemi 8 bolt has a smaller center hole what the crank is using for a pattern is obviously different so we need to find out who makes the crank & what they use

[jimmycuda71]

I still have not determined what brand the Crank is. But I  have another question. Are all RB blocks a 2 piece rear main seal?

[Chryco Psycho]

yes , there is now way to get a 1 piece in there

[jimmycuda71]

I thought that maybe they had sent me the wrong Mopar Performance  flexplate. But according to the part number (312-4527952AB) it is correct. I am going to order a B&M flexplate and see if it makes any difference. Hopefully u just received a defective one.

[jimmycuda71]

Problem solved.  It was a defective MP flexplate. Ordered a B&m one and it went right on.
Thanks for the help.

[Chryco Psycho]

Awesome