[Shiny]

I've found my next trip hazard.

What size/description are these bolts and washers that hold the header to the upper radiator support?

I've been using AMK as a reference and source but they don't have the two part numbers in their database. I'll rummage through my pile of fasteners but I'm trying to use the right ones when I'm able and I trust nothing on this front sheet metal as being original. It literally had a crushed pop can bracing the radiator when I bought it.



PNs as I read them are:

9420760 Washer
9431523 Bolt

Thanks,

Mike

['ol Pinion head]

They attach the top flange of the core support to the header panel. They are coarse thread screw with threads similar to that of a wood screw. 71 standard nose A-bodys used a very similar if not the same bolt, so did '71 Pontiac B series.

[Shiny]

Thanks for the quick reply.

I found these which may be the originals. Do these look right?

Looks like 5/16 x 1-1/8 washer-head and 1" OD washers



I also found these 5/16 x 1" self-tapping bolts that look similar, along with a few 1-1/8" flat washers:



Which looks right?

Thanks,

Mike

['ol Pinion head]

Yes, have a bunch of the top style from '70 & '71 T-37 & LeMans header panels.

[Shiny]

Thank you OPH !!

I'll go with the 1-1/8" pointy ones.

I ran one into the header and it did not bottom out. I would not want to split the header by using too long of a fastener.

I also think the 1-1/8" OD washers look too big, so going with the 1" OD.

Onward!

Mike

[Trevor78]

what are the unknown/unfound part numbers? Won't open large enough to read here.

[Shiny]

Originally Posted by Trevor78

what are the unknown/unfound part numbers? Won't open large enough to read here.

PNs as I read them are:

9420760 Washer
9431523 Bolt

I'm still curious but went ahead and installed the ones in the photo. They seemed to fit fine with the 1" flat washers.

I had a couple stripped out holes in the header I failed to see while I was repairing it so I just squirted in some of the SEM repair epoxy and threaded the bolts in. I'll probably regret it later, but won't be my first bad decision.

[62olds]

Originally Posted by Shiny

Thanks for the quick reply.

I found these which may be the originals. Do these look right?

Looks like 5/16 x 1-1/8 washer-head and 1" OD washers



I also found these 5/16 x 1" self-tapping bolts that look similar, along with a few 1-1/8" flat washers:



Which looks right?

Thanks,

Mike

I’m a little to this thread but I believe that the lower set of self tappers are correct. It may help someone else.

[Shiny]

Thanks 62olds

Perhaps the self-tapping feature makes sense for assembly into the SMC/fiberglass?

Pitch is the same as the pointed ones, so for "re-assembly", the pointed ones (which I used) are probably fine.

But would be good to find a GM description of the part number.