66 Alternator bolt; lower, outer position, threads into exhaust manifold

[Gary B.]

66C65DB0-1B5F-4D0E-B326-4D35B5903825.jpg

77E18333-9FF2-40AB-99A0-D323DB530AA5.jpg

D06FD619-AF3E-4A4C-BC7F-D7EF89CA0BBD.jpg

[Richard M.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

That looks like it came from Ace Hardware.

Functional, but......

Rich

[Edward J.]

[Richard M.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Gary what are the dimensions/specs of the "C" bolt pictured?

Rich

[Robert P.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

The bolt kit from paragon has TR head markings on them, just installed them last week
Bob

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Gary what are the dimensions/specs of the "C" bolt pictured?

Rich

Rich,

My crusty, C headmark bolt is 3/8-16 x 1.0”

The LIC U headmark repro is 3/4” long.

Gary

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

That looks like it came from Ace Hardware.

Functional, but......

Rich

[Richard M.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Rich,

Given LIC’s reputation and resources to bolts with other headmarks, why on earth would LIC sells a U headmark bolt that almost everyone is skeptical of??? Bizarre.

Gary

LIC is one of my favorites but occasionally they don't have exact reproductions of all hardware, headmarkings or even grade. One has to look carefully after researching, especially assembly hardware.

My previous '67 JG comment in your earlier thread was a perfect example. They sent me eight black phosphate grade 8 bolts for the BB inner half shaft cap bolts. I researched the part# in the AIM, found specs in GM Standard Parts Catalog, and found it was grade 5 zinc/cad plated bolt, not even close. BTW, I could've gotten those grade 8's at Napa.

Joe Lucia commented and agreed with my findings. I asked Nick to check in, and they adjusted the JG appropriately.

Paragon has a great chart showing bolt head markings somewher on their website IIRC.

Rich

[Richard M.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Rich,

My crusty, C headmark bolt is 3/8-16 x 1.0”

The LIC U headmark repro is 3/4” long.

Gary

Let me check my bucket-o-bolts I may have one.....Rich

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Rich,

Paragon’s bolt chart starts on page 156 of their PDF catalog. They only have two, Gr 5, trimmed hex head bolts that should work for that lower alternator bracket application. They are shown at the far left and far right of the attached image. The TR headmark makes more sense to me for my ‘66. I’d still like confirmation that 3/4” long is sufficient.

Gary
E4D87198-B186-4E27-A3EB-F59B630277F9.jpg

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Rich,

Thanks. I think a 3/4” long bolt will work, e.g. Paragon item #1943. When I insert the LIC repro bolt thru the alternator bracket, with the lock washer uncompressed, I measure 3/8” of threads sticking out, or one diameter. A bit more once the lock washer is compressed. With the bracket and the lock washer in place, the hole in the exhaust manifold will accommodate my 1” long original bolt. So, either 3/4” or 1” long will work. The 1” long bolt would obviously be more robust.

Gary

PS I think the rule of thumb for a bolt threaded into a hole in cast iron is an engagement of 1.8 to 2.0 x diameter. The 3/4” long bolt will likely not achieve the 1.8x. I’m more and more thinking my 1.0” long bolt is what went there originally.

[Richard M.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Well I went through my bucket but no 3/8-16x1". Sorry.
Rich

PS I'd say 1" was original also. Do we have a part#? I don't see it in the AIM at that location. Just a note about keeping it loose until alternator is mounted. Maybe it was in there at Flint.

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Rich,

Thanks for checking your bolt bucket.

I agree that the part number isn’t in the AIM, so it came already on the engine.

I just found this bolt in the AMK Products catalog.

5D05042D-934C-4D33-972F-8F2054606F2C.jpg

It’s available in either black phosphate or zinc. The zinc seems perfect. So why doesn’t LIC sell those??? Too expensive at $1.50 each? It’s now on my AMK to-buy list. Have to get up to their $30 minimum, which seems to happen to me every few months.

Gary

PS. I believe GM 180122 is the zinc/cad version of that bolt, and GM 9418822 is the black phosphate version.

[David B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

Your part number probably is 179839 3/8-16 x 1 plain

[Gary B.]

Re: 66 Alternator bolt; lower, outer position, threads into exhaust manifold

David,

This is what AMK shows for their repro of GM 179839:

CE4F4751-9B45-4418-A931-61A014E842FF.jpg

I think the white circle near the tip of the bolt is a plastic insert that serves as a locking feature.

Gary