See my last posting and read carefully my statement about recalling something from my memory about a fabric rivet. New rule for me.
Remember I'm 55 and on some heavy meds; Do not rely on memory!!!
Here's what I came up with in my search for the crank hole cover rivets. I knew I had some originals stashed somewhere that I had plated many years ago, with the original washers in the same bag. They were from 28-29 shells. Those are in the first two photos. You can clearly see that the first washer against the back of the radiator shell was a lock washer just as Mr. Karr described, then a flat steel washer was installed, then the rivet was upset to hold in place. You can also see that the heads of these original rivets were quite round, not flat at all.
The next two photos are of the crank hole cover and washer and rivets on a new old stock 1930 radiator shell. You can see that this rivet is brass and not plated. That's interesting. The photo of the back side does not clearly show the lock washer that is installed against the radiator shell. I just couldn't get a photo to show this. But, it's there, right under a flat steel washer.
The next two photos are of a new old stock 30-31 crank hole cover with the rivet and washers attached, that was bought in 1991 from Dave Schaefer. What a stash he sold that year!!! Anyway, you can't see the lockwasher in this photo either, but it is there, right under that brass flatwasher. The 30-31 rivets were quite flat-headed.
This is to illistrate some original parts, and not an attempt to tell Hunter how he should do his crank hole cover installation. Hope my time spent was interesting to someone.
Dave Lopes