'70 LT1 Alternator Pulley & Fan Finish

**mockingbird812** · #1 08-08-2009, 11:39 AM

What is the correct plating for these two items?

Thanks

**Salvatore** · #2 08-08-2009, 03:44 PM

Alt. pulley is silver cadium dichromate and the pulley fan is silver cadium. I have seen variations in both, but close.

**mockingbird812** · #3 08-10-2009, 08:14 PM

If I don't/can't do the cadmium process, what is a suitable substitute plating process that is more readily available? Were the finishes the same for '70 as well as '69 high rpm alternators (-837)? Here is a photo of my Blk/Red 'velle taken on the 2nd day after delivery (note finishes on alternator fan and deep groove pulley):

CamarosRus · #4 08-10-2009, 10:35 PM

Sam, I am not positive as I've never read where anybody has had original parts analized by a lab.
I think that the 70 LT-1 Deep Groove pulley was Cadmium plated or Clear Zinc, and the fan was clear zinc.

Todays platers used a brightner solution after the zinc plating. I'm not sure that was the case when these parts were new, thus they tarnished much faster.

Just my .02

**mockingbird812** · #5 08-11-2009, 12:34 AM

Thanks Chuck - that helps!

TheNovaMan · #6 10-20-2012, 02:42 AM

Did some alternators come with gold cadmium plated fans and/or pulleys?

**William** · #7 10-21-2012, 07:18 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TheNovaMan</div><div class="ubbcode-body">Did some alternators come with gold cadmium plated fans and/or pulleys? </div></div>

I do not believe gold was ever OE. GMPD serviced a generic deep-groove alternator pulley [#3829387] for many years that had a gold finish.

TheNovaMan · #8 10-22-2012, 02:05 AM

What about black?

**firstgenaddict** · #9 10-22-2012, 10:48 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mockingbird812</div><div class="ubbcode-body">If I don't/can't do the cadmium process, what is a suitable substitute plating process that is more readily available? Were the finishes the same for '70 as well as '69 high rpm alternators (-837)? Here is a photo of my Blk/Red 'velle taken on the 2nd day after delivery (note finishes on alternator fan and deep groove pulley):

</div></div>

The mask for the intake and by pass hose must have been mis positioned or slid down, the nub where the fitting screws in is unpainted as is the block at the top edge of the lifter galley wall in the same profile as the intake.

Plowman · #10 10-24-2012, 12:16 AM

This is how GM was finishing them several years ago.

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