VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans Help with 39 Truck Headlight Assembly

I have a question about the proper assembly of a 39 pickup headlight. When I purchased my 39 it had been converted to sealed beam. I have managed to assemble what I believe are all the necessary parts to go back with lens and reflector style lights. My question has to do with gasket that is shown as part 7.0390 in this illustration from the 39-53 GMC Master Parts Book.

The part I received is a split strip of cork, not a solid ring. My assumption is that it is meant to be pressed into the channel on the perimeter of the reflector, and give a cushioned surface for the glass lens to seat against. Two things of note. The gasket/seal is not long enough to encircle entire reflector. When pressed into the reflector there is about a 1 1/4" gap between the ends. Secondly, when seated firmly in the bottom of the channel, the cork sits nearly 3/16" above the lip of the flange. Let's say 5/32" to be exact. This seems to be way to high, and the lens and trim ring will not seat down over the bucket. So my question is, just how much should that gasket be sitting above the flange to be proper. I can't imagine that it's normal to have to trim these things, or at least wasn't when they were available at the parts counter.

It would make more sense to supply the cork strip too long so it could be trimmed to fit. I believe they may have had a staple to join the ends in the "old days"
I think some vendors sell a rubber strip. I installed some on my '36 truck a few years ago and they seemed to fit as I expected but I don't remember if they were rubber or cork.
I suggest leaving the gap at the bottom in case they get some water inside. This does not address your thickness issue.
BTW, That number is a group number. The part number will be found in that group in the parts catalog.

Mike

Thanks Mike. Yeah I'm with you on the leaving the gap at the bottom, and yes, I was referring to the group number. The part number for GMC is 918677. I'm not sure if that's the Guide number, or the GM univeral number or not. Most GMC specific part numbers are 7 digits starting with a '2' and they are a total pain to cross.

So I got my answer. So I ordered these gaskets from Chevs of the 40's. I measured mine at .320" x .242". Considering the channel is .180" x .190 ... It's a tight fit, and the gasket is obviously sticking out way above the lip of the flange. So first I called The Filling Station and had them measure their gaskets. .189" x .189" . Bingo. That makes sense! Even makes sense that you have to wet the gasket so that it swells a little bit in the channel for a tight fit.
I called Chevs of the 40's, and asked them to compare with what they have on the shelf because I figure they'd made a bad batch. They got the same measurements on the current stock ask I have on my gaskets that don't fit. Luckily they are willing to take a return even though I've had these for three years. They insist the parts are right, and that I'm doing something wrong. Well, okay, but I seriously doubt it if someone else has a gasket measures out to be the right dimensions. I can't figure out how they got this so wrong and have left it for so long. It's been three years since I ordered these things.