Can anyone tell me what size the driver's side motor mount to frame bolt is supposed to be? Is it 7/16 by 3-3/4 or something like that? The car is a 71 Charger with a 440.

The one installed now appears to be slightly too small in diameter (like it's metric or something) and it had a nut and washer installed on the backside even though there is a welded nut there.

I would like to just use a hardware store bolt if possible, it's just a driver.

Thank you.

Greg

Are you sure the original welded nut isn't striped? That may be the reason for the undersized bolt.

pretty sure you're correct at 7/16" coarse thread. I'd try running a tap through it. I imagine a smaller bolt would allow a loose fit in the hole so engine could rock if bolt isn't real tight.
If engine is out weld a nut to it, or replace the mount.

Thanks guys. The welded nut being stripped is a good thought, I will check that out. The motor is unfortunately in the car, I had to undo the mount to lift the motor to install my new steering box.

Why would anyone put a stripe on a nut?

Me thinks he means stripped, not stripe

Its a mopar, everything gets a paint daub

To make silly people ask questions.

I got all excited when I saw there were 4 more responses to my question...

But, did you fix the motor mount yet? If there is enough space, you can jut add a nut on the outside of the threaded block to tighten the moror mount bolt. That won't pass a restoration test, but it will function on a driven car. Gene

Just measured 1 it is 7/16 " x 4 1/2" long coarse thread

Thanks guys. I can just put it back together with the nut on it, but I was struggling with it to the point of frustration because there is not a lot of room to feed the nut up in there and get the bolt to engage with it. So I gave up and was wondering why it wasn't "right" and if there was a way I could make it so.

One way or another I will figure it out. I am excited to try my new Firm Feel Stage 2 steering box, so I am anxious to get everything back together.