Flathead Main Cap Bolt Lengths - Different lengths?

[Brian]

No, sorry, I have no pictures of main caps. I don't have a C69A apart at this time. As I said in an earlier post, i always fit studs in those blocks anyway.

[Ol' Ron]

I;m not that smart. I think Bill Barth told me that. I saw him doing that to a SBC. Also JWL does it aswell. There are allot of smartpeople out there and I just pass it along.

[GOSFAST]

Just a tip, forget using any bolts, put in a stud kit and be done>

All our builds nowadays get main studs, we put the kits together in-house using all ARP fasteners!

They use .125" thick flat-washers under each nut. We spot-face the original registers on the main cap for a fresh surface!

Thanks, Gary in N.Y.

P.S. Here's a shot of one laid out with the studs, the nice part about the studs we use they can be adjusted in or out up to a .625" or so as needed! The other shot is one with main cap straps included, these studs are just a bit longer O/A however!

[Ziggster]

Stopped by the machinist this morning. The Speedway/ARP bolts are about 1/4" too long. Also the shoulder just under the head which is a larger dia than the shank interferes slightly with the bore in the cap. The orig bolts have a much larger head and appear to be in good shape, so I'm sticking with them. Lock washers were originally used, but I'll swap out those with the flat washers that came with the new bolts. I'll call Speedway next week to see if they can explain what the issue is.

[marko39]

Originally Posted by Brian

These photos are of original C69A main bearing bolts. They differ in the head configuration; the ones that use spring washers have six slots and a recess, whereas the non washer using bolts have six slightly raised ridges around a raised 'B'. Both bolts measure at 2 15/16" long.

On my 51 block the bolts are like the ones you show except the front two are the slotted ones and center and rear that use washers are the other ones and are longer, about 3 1/16. When I took to machinist for alighn honing he told me to leave lock washers off the front cap.

[Ziggster]

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All the bolts that were on my block (it was rebuilt at some point by a Ford authorized dealer) are like the slotted ones in the attached pic. My machinist and I are still not clear how washers under the two front bolts can interfere with the pan. Looking at the shape of the cap and where the heads of the bolts are located, I can't imagine how the thickness of a washer could cause an issue.