What Finish on Lt-1 Intake Manifold Bolts?

[Christopher K.]

Are they Black Phosphate, Zinc, or Cad? All the ones I've seen are rusted now so I can't tell.

Or does it not really matter since the manifold is painted with "dull aluminum paint"?

I've seen a lot of different answers so thanks for your help!

[Ron G.]

Re: What Finish on Lt-1 Intake Manifold Bolts?

Christopher,

Intake bolts are black oxide with silver paint over the out board side of the bolts. This is because after the orange paint was sprayed, they removed the travel rocker covers which were standard valve covers. In an attempt to cover the orange overspray they would spray silver paint out of a rattle can to eliminate most of the orange that was on the intake. Also, original type cars or a correct restoration would incorporate silver paint on the inboard of the aluminum valve covers as this was performed after the LT-1 valver covers were installed. Hope this helps.

- Ron

[Christopher K.]

Re: What Finish on Lt-1 Intake Manifold Bolts?

Thanks Ron,

That makes sense about the silver paint application, it certainly wasn't done neatly.
I have read about Black Phosphate bolts on the intake, but I did not know Black Oxide was used? I know black oxide will wear/rust relatively quickly compared to phosphate.

[Ron G.]

Re: What Finish on Lt-1 Intake Manifold Bolts?

Christopher,

Based on my many years of experience, I am of the opinion that black oxide is far superior than phosphate and possesess higher quality properties regarding rust. Again, just my opinion and what I have observed over the years.

- Ron

[Christopher K.]

Re: What Finish on Lt-1 Intake Manifold Bolts?

Ron,

Google was my primary reference:

Black Oxidising on ferrous , also called as blackodising, is a decorative finish and has very limited corrosion resistant properties.A suitable grade of Rust Preventive oil will increase the life. If a dry film as top coat is permissable, thin film of clear PU, epoxy or other lacquer will give far better life. Zinc-iron, Zinc - calcium, manganese-iron phosphating with suitable anti rust oil will give longer life. Manganese phosphating produces dark grey finish. Alternatively Zinc plating with black passivation will serve the purpose.

Thanks for your help, I will defer to your opinion, since I have no personal experience in this area.

[James G.]

Re: What Finish on Lt-1 Intake Manifold Bolts?

Christopher,

This is because after the orange paint was sprayed, they removed the travel rocker covers which were standard valve covers. In an attempt to cover the orange overspray they would spray silver paint out of a rattle can to eliminate most of the orange that was on the intake. Also, original type cars or a correct restoration would incorporate silver paint on the inboard of the aluminum valve covers as this was performed after the LT-1 valver covers were installed. Hope this helps.

- Ron

I do not believe I am out on a limb to state that the FLINT machining, assembly, firing, & painting processes for the LT1 and the Z28 engines would be virtually identical minus gang stamp suffix ID's.

I have an extensive history with high performance Camaro's and with John Hinckley's postings on the Camaro Research Group regarding processes at Flint and Tonowanda.
My understanding is the Z28 LT1's were painted fully assembled, the finned aluminum valve covers were installed on the engine as well as the intake and both were covered with a vacuum formed plastic mask, the masks were formed on a vacuum table on site.

The plastic masks would curl after repeated uses and allow more and more over spray on the edges, until being replaced.
Many Camaro LT1's have orange painted plug wire stands(brush) and extensive brushed silver paint on bolts, brackets and the ends of the intakes...

My own 2 owner 71 LT1 Corvette which has never had the engine out has silver brushed on the intake bolts and over the front pull strap...

Is there documentation verifying that the Corvette engines were different, and shipped to St Louis with tin covers and then replaced with finned Aluminum at the assembly plant?

[Ron G.]

RgodutiLT1@yahoo.com