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**71CHEVYSHORTBED402** · 08-09-2020, 05:10 PM

Well Deadhead, I'm a little stumped on this one. You're right assuming the original bolts were say a much lighter manganese than the pictures and parts I have available. Per that website post 180, manganese is less than desirable. Could explain why inner fender bolts bust right, which is where I'm using the NOS in the pics. below

The images are of NOS bolts, and a comparison to a replacement bolt that's clearly Manganese. The picture doesn't illustrate the difference between the two. I can see light crystals on the NOS bolts, but only under direct light, even with my glasses on

. The replacement bolt is heavily crystaled, easy to make out and there's a heavy sandy feel to it.

I blew-up the example of zinc phosphate in post 180, seems I can make out some crystals. Their description isn't clear where it reads "doesn't have the heavy crystallization of Manganese", can't tell if that means light or no crystals at all.

08-09-2020, 05:10 PM	#180
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: Build that 71 402 already Well Deadhead, I'm a little stumped on this one. You're right assuming the original bolts were say a much lighter manganese than the pictures and parts I have available. Per that website post 180, manganese is less than desirable. Could explain why inner fender bolts bust right, which is where I'm using the NOS in the pics. below The images are of NOS bolts, and a comparison to a replacement bolt that's clearly Manganese. The picture doesn't illustrate the difference between the two. I can see light crystals on the NOS bolts, but only under direct light, even with my glasses on. The replacement bolt is heavily crystaled, easy to make out and there's a heavy sandy feel to it. I blew-up the example of zinc phosphate in post 180, seems I can make out some crystals. Their description isn't clear where it reads "doesn't have the heavy crystallization of Manganese", can't tell if that means light or no crystals at all. Attached Images __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 08-09-2020 at 05:52 PM.