C1-aluminum valve covers

[Kurt Michael]

I have several questions regarding the use of aluminum valve covers:
1.) I have a pair of 7-fin alum. covers, GM #3726086 with the staggered bolt holes. What year(s) were these used?
2.) What year(s) were the 7-fin alum. covers with the straight bolt holes used without the casting flaw through the "o" in corvette.
3.) What year(s) were the 7-fin alum. covers with the straight bolt holes used with the casting flaw through the "o" in corvette.

I have a late '61 with the 7-fin alum. covers with the straight bolt holes and the casting flaw. I am trying to determine if these are correct or not.

Thanks for your help!

[Jack Layton]

Re: C1 & C2 Al valve covers

7 fin straight hole no casting flaw through the "O". 1966-1959. 1958 maybe partial year.
7 fin straight hole, casting flaw through the "O". 1967 (early cars may have no flaw)
7 fin angled holes. 1958E, 1957?
9 fin angled holes. 1957? , 1956.
There are some variations on the cut outs for F. I. motors.
I think there may be some distinction in the height of the CORVETTE script and maybe the fins as well on the above first and/or third set. The earlier versions having a more pronounced or higher lettering.
In any event the casting flaw was not a planned design feature but an industrial accident in 1967. Hence, the casting flaw would not be original to a 1961 Corvette.
Would make a nice article for the Restorer if it has not already been written.

[Terry Leeker]

Re: C1 & C2 Al valve covers

It was my understanding that all 58's had staggard bolt hole valve covers, Aluminum and steel? If not, what was the sn break.

[Dave S.]

Re: C1 & C2 Al valve covers

The staggered holes were present in all 58 Corvettes and into early/mid 1959. The staggered bolt 550 heads were changed to 465 sometime in May or June of 1959.

[Jack Layton]

Re: C1 & C2 Al valve covers

Allow me to amend set number one. I belive the staggered hole covers were through 1958 but changed some time in 1959. One would need the Judging manual for exact dates on each individual alteration. I have tried to paint the issue with a broad brush to give you and overall view of what was going on with the covers.

[Roy Braatz]

Re: C1 & C2 Al valve covers

Staggard- eariler is less pronouned then later 7 fin replacements

[Clark McEwen]

Re: C1 & C2 Al valve covers

In or about May of 1959 the bolt pattern changed from staggered to straight, with any mid year change there was a bit of a phase in period while they used up old stock.

CM