197?-82 Valve Cover ID

[Dan A.]

I have a pair of alloy valve covers that I no longer remember what they were made of. I suspect aluminium.

The left cover has two "sets" of parts numbers cast inside:

14025553 L.H. MAG
14025554 R.H. MAG

474208 R.H. ALUM
474207 L/H. ALUM

It has a cast date that looks like a clock with dots in the outer circumference and 85 in the centre.

Is this one aluminium or magnesium? The magnesium are no longer available in this area. The aluminium are.

The right has only one set of part numbers (not casting numbers). They are much fainter to read than the left cover and a different font. They are:

CAV
14025553 LH
14025554 RH

Same type casting clock with an 83 in the centre.

Is it aluminium or magnesium?

Naturally I will appreciate any assistance with these "Snow Tire Car" parts.

Dan

[Joe L.]

Re: 197?-82 Valve Cover ID

Dan-----

The only C3 Corvette valve covers that were magnesium were the 81-82. These were the GM #14025553 and 14025554. These valve covers can be identified by the fact that they have a black "powder coated" surface over most of the exterior of the cover with the exception of just the tops of the ribs. If either of the valve covers that you have match this decription AND have the numbers inside that you decribed, then they are magnesium. Magnesium valve covers for Corvettes were NEVER produced with a natural or polished surface.

Not all Corvette valve covers with black coated exterior surface are magnesium, though, the 78-80 L-82 valve covers were black coated just like the 81-82, but these valve covers are aluminum.

[Dan A.]

Aluminium or Magnesium

The pair I have are black coated with the exception of the top of the ribs and around the oil filler cap hole on the right one. As I posted the one has only the magnesium part numbers for left and right cast inside. The other has both aluminium and magnesium left and right part numbers cast inside.

Here in Canada the aluminium ones are still available at a whopping retail price of $255 each. The magnesium do not even show as discontinued.

These have never been mounted on an engine.

So I'm faced with due diligence to determine which they are aluminium or magnesium?

Dan

[Joe L.]

Re: Aluminium or Magnesium

Dan-----

Given the description that you provided and the numbers embossed on the inside of the covers, I feel fairly confident that the ones that you have are magnesium. However, if they were very late SERVICE replacements, it's hard to say. Here's the deal:

The original black coated, ALUMINUM valve covers used for 78-80 were GM #464667, left, and GM #464668, right. In the early 80s, these were "replaced" for SERVICE by the 81-82 PRODUCTION magnesium covers, GM #14025553 and 14025554. Actually, I think that the former part numbers continued to be "in the system" but were for some unknown reason, deleted from the P&A Catalogs after 1979 and the magnesium valve covers were sold in SERVICE for all 78-80 L-82 and all 81-82 applications.

In June, 1989, the GM #14025553 MAGNESIUM valve cover was discontinued and replaced by the ALUMINUM valve cover GM #464667. In April, 1990, the GM #14025554 MAGNESIUM valve cover was discontinued and replaced by the GM #464668 ALUMINUM valve cover.

Now, the "kicker" is that I'm not sure that the numbers in the molds were changed and I think that it's POSSIBLE that the SERVICE valve covers made after about 1990 were aluminum (as indicated by the PART numbers), but they MAY have carried the earlier numbers on the mold.

One other thing that you can do, though, to identify them is this, especially if they are new valve covers: magnesium is a darker, silver metal than aluminum. So, the ribs on the top of the magnesium valve cover will appear quite a bit darker than the aluminum versions. If you can compare the ribs to a NEW GM #474207 or 474208 valve cover (the 69-77 polished aluminum valve covers), you should see a marked difference in the coloration of the metal on the tops of the ribs between the 2 valve covers IF the ones that you have are magnesium. If the metal looks the same, then the ones that you have are aluminum.

One other thing: the last SERVICE replacements for the 78-82 valve covers, the GM #464667 and 464668 are discontinued, at least here in the US. The 464667 was discontinued last year and the 464668 was discontinued in March, 2000. Both are available in reproduction from Paragon, though, and I believe that they are made from the original molds by the original supplier to GM.