Big Block Chevy to 700R4

[1969CamaroRS]

Anyone ever done this? Looks like my big block flexplate has 2 bolt patterns on it, but neither one lines up with the torque converter on the 700R4 (700 has a even narrower pattern).

I been going around and around for two days now trying to figure this out.

First called a transmission shop, they said need to switch out the flex-plate as the torque converters for the 700R4 are pretty standard in their bolt pattern.


Then Called Eagle Specialty (people that made my rotating assembly), asked them about the balancing weight on the flexplate (so I can order another one that will bolt up). Big Blocks should be externally balanced but they claimed the weight on the flex plate is standard, but didn't know what that weight was?!?

But the transmission guy that was going to order me flexplate says he needs a balancing weight so that he order the correct one. :banghead:

Eagle said their big block guy was out and they would get back to me as far what the solution is. Hopefully they can give me part # that will work next week.


Last resort I guess would be to elongate the holes in the flexplate but being that there are only 3 mounting holes for the torque converter monkeying with them doesn't seem like a good idea. Especially since the high performance torque converters have 6 bolts and the torque of a big block (~600 ft-lbs).

I'm just trying to bolt up the 700R4 for now so I can get the car running until I can afford to build/buy a 4L80E.

Any ideas? Thanks in advance. https://static1.pt-content.com/images/pt/2007/12/beers-1.gif

[Firehawkslp]

As I recall the differance is only about an 1/8th of an inch. This is easily within the tolerance of the factory mounting holes, a little more hasn't hurt so far. But that application didn't have near the torque.

THe other idea is to measure the diameter of the bolt circle on the torquer converter and drill a new pattern. The balance is on the flexplate and it won't change relative to the crank.

Last but not lest you could try contacting someone like "Bowtie overdrivers" they have got to have run into this problem and have a solution.

[1969CamaroRS]

Thanks for the response. I ended up unmounting the trans, counted the splines on the 700R4 and found out its a 27 spline unit. Also measured my flex-plate which ended up being a 11.50 bolt pattern while the bolt pattern on the torque converter is a 10.75. The 700R4 is in good shape and didn't really make sense to me to use that as I would just end up breaking it.

So I just decided I'd go with a built trans as it doesn't look like I will be able to rebuild my own.

Thanks thou!

[GetMore]

On top of that, the 27 spline version of the 700-R4 is weak.
If you had used it you would be one of those people complaining about how crappy they are.