Cam Adjustment Assembly, 3820253, markings

[Alan D.]

The rear camber adjustment is accomplished by the Cam Assembly Bolt, 3820253. The cam section has various markings on it. I have seen (1) a single hole, (2) hash markings, (3) single hole & hash markings, (4) single hole, hash markings, & "M" and (4) solid with yet another mark.

Just what years were these various markings used during? Concerned about C2s, but other information is welcomed.

Please just focus on the markings & not other features. Yes have done search, but didn't find anyone addressing that subject.

[Wayne M.]

Re: Cam Adjustment Assembly, 3820253, markings

Here's the type "3" that Alan describes. This is the original off my late 396. We were discussing these variations by email, about 3 weeks ago. Notice the faint "M".

The accumulated "crud" protected most of the metal surfaces .

[Alan D.]

Re: Cam Adjustment Assembly, 3820253, markings

And here is an original one from a March 64 car, hole only. Note the "M" is on the backside.
Should have posted at the start
So with very little data the hash marks started in 65 +/-

[Joe L.]

Re: Cam Adjustment Assembly, 3820253, markings

Here's the type "3" that Alan describes. This is the original off my late 396. We were discussing these variations by email, about 3 weeks ago. Notice the faint "M".

The accumulated "crud" protected most of the metal surfaces .

Wayne-----


This one is absolutely identical to the original bolt/cam assemblies on my 1969

[Joe L.]

Re: Cam Adjustment Assembly, 3820253, markings

The rear camber adjustment is accomplished by the Cam Assembly Bolt, 3820253. The cam section has various markings on it. I have seen (1) a single hole, (2) hash markings, (3) single hole & hash markings, (4) single hole, hash markings, & "M" and (4) solid with yet another mark.

Just what years were these various markings used during? Concerned about C2s, but other information is welcomed.

Please just focus on the markings & not other features. Yes have done search, but didn't find anyone addressing that subject.

Alan-----


Beginning in the mid 1977 model year, the cam/bolt assembly used for 1963-E77, GM #3820253, was changed to GM #458979. This cam and bolt assembly also became SERVICE for 1963-E77. The 458979 has the degree marks and the hole. However, both the cam and the bolt were zinc plated. The 3820253 used a black phosphate-finished bolt with a plain steel cam. The separate cam on the other side was always the same from 1963-82 and was zinc plated.

In addition, the 458979 usually has a bolt with a headmarking of 5 or 6 radial lines. In the center I have seen "H" and "M" in a circle. There might be others.

[Alan D.]

Re: Cam Adjustment Assembly, 3820253, markings

"Beginning in the mid 1977 model year, the cam/bolt assembly used for 1963-E77, GM #3820253, was changed to GM #458979."
So from our limited data the 3820253 used on C2s started out with only a single hole - used in 63 &64 then sometime in 65 the hash marks got added.
I suspect the the "M" on the plain finished cam sometimes faced out and sometimes in - don't think anyone even looked during assembly of the 3820253.