Flexplate to converter clearance [Archive] - Chevelle Tech

: Flexplate to converter clearance

May 24th, 03, 4:57 PM
I'm currently installing my second 396 in my car that hooks up to 700r4 transmission. My first motor had some problems that I won't get into now. When installing the motor and tranny the clearance from my torque converter and flexplate is about 5/16 of an inch. On my first motor I had less than 3/16" which is what it is suppose to be. The only things that have changed is my block, crank and torque converter (I went from a 3,000 stall to a 2200 stall). I'm not sure what my problem is seeing the torque converter is correct and the flexplate is a externally balance plate that worked great the first time. Also the company that put my motor together is very reputable and trust there work. Can I shim or do I need a different flexplate or??? Any insights would greatly be appreciated.

May 24th, 03, 5:13 PM
I was told by my tranny guy that, with the TQ converter all the way back engaged in the pump, there should be no more than an 1/4" gap between the converter mount lugs and the flex plate.
If the gap is greater, according to him, it is acceptable to use spacers (washers) on the bolts, placed between the converter and the flexplate. This is to keep the converter "ears" fully engaged in the pump.
Again, I'm not a tranny guy. This is what I was told by a tech who has done trannys for many years...

Oldani Motorsports
May 24th, 03, 7:47 PM
You want from 1/8" to 3/16" clearance before the bolts are drawn up. If you have to add in a spacer of some sort, there is one important thing to remember. That is to be 100% sure that the pilot on the converter still engages the hole in the back of the crank. If you space it out too far, and the pilot will not fit in far enough, you will have some big troubles. The simplist way is to take a flashlight and look up from below and see how far the pilot is engaged. Should it not fit, there are some alternatives, such as tack-welding a ring on the pilot to extend it. IMO, 1/4" is too much end play. It allows the drive gear for the pump to rock around, and if it is pulled out too much, it can rip the tangs off the pump. Too little end play will shove the drive gear of the front pump into the pump and tear it up also.

May 24th, 03, 8:01 PM
Not to get off the subject but why are you using an externally balanced flexplate on a 396?
Torque converter manufacturing intolerances vary so that may explain the difference in clearance.

May 24th, 03, 9:26 PM
Thanks for the replies...

I will see how the pilot on the converter lines up to the crank after I shim 1/8". I hope this works.

Jay72...Sorry, I have my mind on a 454 that my buddy is building, which we have been working on in his garage. It is externally balanced...not the 396. I'm pretty sure though that both flexplates are the same except one is balanced? Correct me if I'm wrong... :confused:

Oldani Motorsports
May 25th, 03, 2:05 AM
If it does not fit in the crank enough, email me, I have some parts to help you out, or can explain what you need to do.

May 25th, 03, 12:54 PM
Originally posted by Austin:

I'm pretty sure though that both flexplates are the same except one is balanced? Correct me if I'm wrong... :confused:
Austin You are correct. ;)