Unusual stylized P headmark

[Gary B.]

Has anyone run across this stylized P headmark on any bolts or machine screws on C2 cars?

Gary

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[Michael G.]

[Jimmy G.]

Re: Unusual stylized P headmark

Never seen one. But as I tell everyone about bolts -- anything is possible. For NCRS go with another bolt that everyone recognizes

[Gary B.]

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[Michael G.]

Re: Unusual stylized P headmark

Pioneer was a fastener supplier that I dealt with a lot during the years I was at GM. It’s very likely that they were a partial (or back-up) supplier of many parts used on C2s. They might not have been the major supplier of any part normally found on the Corvette line, but GM split their purchase of many, many parts among multiple suppliers. It is very likely that if supplies of another company’s version of a part ran low at the Corvette line, Pioneer’s version of that part could have been shipped and installed there regularly.

This is one of the tricky things about “typical” fastener usages in judging. A part may have have a “normal”, expected head marking, at the Corvette plant, but St. Louis was huge and GM was enormous. Back-up versions of any part could easily be summoned from other lines at St Louis (and other plants), or purchased outright from any supplier by a Corvette plant buyer. It was done without permission of engineering or anyone else. Such a back-up part could easily have been mixed with and in the same bin as the “normal” head marking on line and must still be considered as a normal production part for judging.

If you find a part on a Corvette that is otherwise identical (except for head marking) to the expected part, and the marking was of a GM supplier of that era, it must be considered as a possible part installed at St Louis. That goes for Flint engines too.

[Michael M.]

Re: Unusual stylized P headmark

I have not seen this head marking on to many C2's. It is more of common head marking for cars that were built in 1969 or C3's.

[Gary B.]

Re: Unusual stylized P headmark

Michael,

Do you recall where those bolts went on C3s/69s? Were any 1/4-20, which is what the one in my photo is?

Gary

[Joe L.]

Re: Unusual stylized P headmark

Michael,

Do you recall where those bolts went on C3s/69s? Were any 1/4-20, which is what the one in my photo is?

Gary

Gary------


The bolt pictured is a GM 275-M material grade. Every example of a 275-M fastener I've seen is non-trimmed ("indented") head with captured washer and, usually, piloting ("pointed") tip. Most are phosphate finished but some are zinc.

[Michael M.]

Re: Unusual stylized P headmark

Gary,

I have seen the "P" head mark in several locations. The bolts for the front sway bar brackets, the three bolts that hold the windshield wiper motor to the firewall, and the alternator adjusting bolt. I am sure there are other locations. I do not believe that any of the bolt locations I mentioned are 1/4-20.

[Gary B.]

Re: Unusual stylized P headmark

Joe,

The 1/4-20 bolt in my photo has a captured lock washer, so it seems very typical of your description.

Gary

[Gary B.]

Re: Unusual stylized P headmark

Michael,

Thanks.

Gary