Flex plate crank bolt craziness?

[Chad Hilburn]

Hey, guys, I'm running into a weird situation. Most of the flex plate bolts that bolt, the flex plate to the crank on a mopar big block are supposed to be 7/16 thread. I've got a 383 that is a early 68 engine. It may even have a 67 casting date. But i'm telling you, the seven sixteenths bolt won't fit into the crank holes. There's got to be a smaller size? Anyone run into this?

 

[ckessel]

Never. Doesn't mean it never happened though. Run a tap through it?

 

[33 IMP]

Have you got the right thread? 7/16-20? (I do not mean to insult, just asking. You seem to have an unusual problem.)
Are you sure you don't have Metric bolts? Or 1/2 inch.?

There has to be a reason.

 

[Chad Hilburn]

Never. Doesn't mean it never happened though. Run a tap through it?

Hey there, no, they are actually smaller. Ran a fine thread 3/8 thru there and fits perfect. This is the second time I ran into this. Just recently we got a 7/16-20 set of arp bolts for his, and same thing. Too big. Had to go to next size down

 

[Chad Hilburn]

Never. Doesn't mean it never happened though. Run a tap through it?

It literally appears to be a 3/8 thread. 2nd time ive seen this recently. 7/16 is way too big a bolt

 

[Chad Hilburn]

Have you got the right thread? 7/16-20? (I do not mean to insult, just asking. You seem to have an unusual problem.)
Are you sure you don't have Metric bolts? Or 1/2 inch.?

There has to be a reason.

I'll tell you what it literally is a smaller bolt, all six of them. I got what I think is a 3/8 fine thread holes

 

[MWbirdLOVER70]

Ok then try it id say

 

[oldkimmer]

Can u post some pics as I have never seen that. Thanks. Kim

 

[Chad Hilburn]

Hey guys, I finally figured out the ridiculousness on this. So you are all right and it's as I suspected too its a 7/16 bolt. Why then did the a r p package say that it fit three eighty three and four forty, yet it was a half inch bolt? Well it was a labeling problem. They clearly labeled hemi flex plate bolts. As a regular big block. I figured it out and called them so they would correct it