C2 Aluminum Valve Cover Casting Crack

[William V.]

Does anyone know when the casting crack started to appear on the C2 aluminum valve covers and were there any production corvetts where these covers were used?

thanks

Bill

[Jeff S.]

Re: C2 Aluminum Valve Cover Casting Crack

The '66 Judging Guide says late '66 (~March cars, ~#17,000). Doesn't appear that they never made a new die, so all '67s (& today's repros) would be expected to have that flaw through the "o".

[Dennis C.]

I would comment that the mold flaw...

...started life (1966) as a very small defect and grew as time went on. If you really cared, you could probably date the rocker cover by the severity of the mold flaw as it progressed in size. The current day GM covers are enough to make your eyes water. DC

[Chris H.]

Re: I would comment that the mold flaw...

Dennis, a bit confused by your crack that got bigger over time. When I look at a cover with the defect I see a mold line that goes from one side to the other. This looks like the die maker cut off one end of the die that was defective and made a new partial die. Keeping that mold line invisible would be impossible, especially for any length of time.

Chris

[Tracy C.]

Re: I would comment that the mold flaw...

Chris,

What our beloved Dipstick is trying to say is that when the mold initially cracked, it was a very clean break and the transfer into the part was very minimal (but not invisible).

Over the years and thousands of runs later, the edges of the crack have degregated to the point where the crack is much more pronounced and the transfer into the part is VERY obvious.

I can personally vouch for the accuracy of his comment however. I've seen covers with the mold flaw line accross the "o" that was so faint you needed to hold the cover in the light "just so" to even see the flaw. The modern day examples are so pronounced, the flaw can be seen from 10 feet away.

While covers without the flaw are rare, the ones with this "fine line" flaw are much more difficult to find.

tc

[Chris H.]

Re: I would comment that the mold flaw...

wow, the line is just perfectly straight. I would think that it would not be that expensive to get such a strait crack fixed. It goes right thru the O and a good die maker could fix it w/o a trace.

Chris

[John H.]

Re: I would comment that the mold flaw...

The crack is still in the mold today, which is still making parts - Paragon owns it.

[Chris D.]

Re: I would comment that the mold flaw...

"Crack" in the mold has always sounded fishy to me when you see a dead straight line. Seems if a mold was damaged it could easily be repaired or replaced. A casual observer without benefit of the oft repeated history might guess the supplier simply made an intentional mold change for cost/processing reasons. Are there any eye witnesses to the inside story?