Bolt of the Day 9/20/11 N headmark grade 5

[Christopher A.]

Goofed on the title and put N instead of D-sorry!

1966 427 Corvette with A.I.R.(air injection reactor)

This bolt may or may not have been black phosphate from the factory. I put the new coating on it when i was restoring my other black phosphate bolts because I saw indications on the head and under the head of the bolt that lead me to believe that it was black phosphate from the factory.

Anyway, this bolt has a raised D on the head and 3 raised lines extending out, which i believe indicates that it is grade 5.

-It appears to be a 5/16" bolt with course threads

-The length is from under the head to the tip is 2".

-The length of the threaded portion of the bolt is 1-1/4" and the non threaded portion is 3/4" long.



Again, ignore my metric measurement tape and go by the measurements above.





Thanks!

[Rich P.]

Re: Bolt of the Day 9/20/11 N headmark grade 5

Chris,

typically this D headmark did not show up on production cars till 70-ish. I would not expect to see this on a mid year. Most likely put on after in service.

Rich