Spare Tire Tub mounting screws 171110

[Ed S.]

I am "revisiting" the issue of the description of the screw used to secure the spare tire tub, # 171110, for a 1964 Corvette because two previous threads on the subject do not answer my question. Question is, what is the correct head marking for this screw? One vendor says "D", another says "LG", a third says "E", or is it possible that there should be no marking on the head of the screw? The screw (actually it is a short, fine thread, recessed hex head bolt) I removed from my car had no head marking? The judging guide specifies this "screw" should be black phosphorous but does it not mention anything about head markings.

So, what is the correct head marking for 171110?

BTW - it is used with a zinc washer, which I have.

[David B.]

Re: Spare Tire Tub mounting screws 171110

If your part # is correct 171110 is a Type C Hexagon Head Tapping screw 5/16-24 X 1/2" long Cadmium or zinc.
GM Standards do not list a black phosphorous type C Hex Head Tapping screw. Still did not answer your question but if your screws match the above description chances are they are correct. Judging guide might want to revisit and Vendors clean up there crystal balls.

[Ed S.]

Re: Spare Tire Tub mounting screws 171110

David, Thank you - that is interesting but not surprising. I suspect a lot of references are suspect after all these years, including some by GM. The bolts I removed from my car look to be original. Over sprayed with a think coat of silver paint by a previous owner - black phosphorous is visible under the paint. Regarding head markings, I received private messages from two experienced judged and both indicate anything is possible, D, LG, E or no markings at all - they have seen all these variations over the years. I think I will go with my original bolts, no head markings and give them a black phosphorous treatment - to comply with the Judging Guide - easy to change if the guide is ever updated. Thanks again.

[Alan D.]

Re: Spare Tire Tub mounting screws 171110

Here are some originals from a Mar 64. Remember many, many manufactures were use for nuts/bolts so head markings are many. As long as the manufacturer existed in the time period you are in good shape assuming the judge knows that which most do. Error these are 5/16X24 (not 20)
Alan