[Pontiac Dave]

Well, not quite 20.......I'm replacing the fuel tank support bolts on my bird. The old bolts that came off had three marks, which I believe makes them a grade 5. I went to a local bolt supplier and bought some carriage bolts with 307A markings on the head. I did some research on the markings and found out that the bolt is equivalent to a grade 2 bolt.

I tried to locate some grade 8 bolts carriage bolts, but nobody seems to carry grade 8 carriage bolts. My first question is...will a grade 2 bolt be sufficient enough to hold the fuel tank up? Which grade did they use from the factory? Is stainless steel a better choice?

Also, the factory torque specs calls for 80-110 in. lbs., which to me seems like not alot of torque at all for the nut to frame bolt. Is it wise to double nut this nut to keep it from backing off or the use of a little Loc-tite? I'd hate to go the Loc-tite route, just in case I ever need to replace the bolts again for any reason. Any advice on this? Thanks in advance.

[69TAPOSER]

I would shy away from using stainless bolts for structural-related parts. Stainless is great for show and maint. but is not nearly as strong as a grade 5 (as an example, overtighten one and you will discover how easy they are to break).

I just installed a Rink's tank in my car and I believe that the carriage bolts included are grade 5. Grade 5 is a good bolt and should be plenty sufficient for the fuel tank.

As a general rule, I try and use Grade 8 whenever possible, but they can be harder to find in certain dimensions.

Phil

[67 455 Bird ragtop]

Totally Stainless carries some bolts that are grade 8 or stronger. Not sure of they sell carriage bolts that fall in that category. Might give them a try.

[Pontiac Dave]

Thanks for the replies gents. I located some grade 5 bolts and I am good to go!

[firebird69racer]

If you need regular tap grade 8 bolts, Lowes carries them. They have a big assortment of nuts, bolts and fasteners, also copper terminal ends for doing battery cables