I have a SBC 350 cast in 68-79. I need to know what flex plate to use to attach a 700R4E trans. The torque converter lines up with the existing flex plate and it uses 10mm bolts but the three holes in the flex plate are about 1/2 in. Seems that will not produce a tight fit. Any help is appreciated.

 

I swapped an '85 Camaro engine into a '78 car. The '78 had a bad flexplate (ring gear) with a TH350 trans.

I used the flexplate from the '85 engine that had a 700R4 connected to it. Other then the mangled ring gear teeth it was identical.

Not sure if that answers your question.

RBob.

 

That’s worth a try RRob. I just can’t get over the 1/2 inch diameter holes in the flex plate to run 10mm bolts through.

 

Any chance someone drilled the flexplate to TQ holes larger?

Before I started the '78 to '85 engine swap I stopped at my local auto parts place. The '85 Camaro with the 305 & 700R4 used the same flexplate as the '78 El Camino with the 305 and TH350.

Both engines were a 2-pc rear main seal. Same flexplate part number for both setups.

Since engine torque is always in the same rotational direction. Maybe oversize holes doesn't matter?

RBob.

 

10mm bolts with 13mm holes - should be normal. 1mm on either side. That's about how much play there is between the holes and bolts on my 86. Sounds normal to me. Tighten till you hear the casting crack and then back it off 1/4 turn.

GD