Nine Fin Valve Covers

[David D.]

What is the application for nine fin valve covers? What years did they appear and how many varieties were there? How were the different applications broken out for seven and nine fin applications? Were the fuel injection 57's unique with the notched fins? Is there any conjecture about the short and tall script for the early covers in general? I believe these parts were all stamped with the LESTER name, so does this rule out the different supplier possibility?

A couple old Corvette nerds were trying to hash this out to no avail, so I thought you folks might offer some reasonable theories or possibly facts.

[Bruce B.]

Re: Nine Fin Valve Covers

The 9 fin aluminum valve covers were used in 1956 and part of 1957.
In 56 they were used on all engines except the base engine 210 HP which used the steel covers.
In 1957 the 220 HP base engine used the stamped steel valve covers. All other engines used the 9 fin covers until around February when the 7 fin covers were starting to be phased in. It is said the phase-in took until June, then only 7 fin covers were used except on the base engine.
The cut reliefs in the fins for the fuel injection air cleaner clearance are still a question to be clarified.
All the 9 fins were low script.

[David D.]

Re: Nine Fin Valve Covers

Thanks for the info.

[Stuart F.]

Re: Nine Fin Valve Covers

I believe I have read somewhere that it was indeed the Fuel Injection air filter interference problem on the 9 fin that led to their replacement with the 7 fin. In fact, it is probably a no brainer, but to accept that we would need to hear it form a more knowledgeable authority.

Stu Fox

[Bruce B.]

Re: Nine Fin Valve Covers

Stu and David.
I have an early 57 FI car and I did have the air cleaner interference problem with the valve cover. I was getting ready to have my 9 fin cut and I was told don't do it. The best remedy is to use the one piece 1/8 inch thick gasket which provided plenty of clearence and also sort of provides a barrier from the engine heat.
Also, the nine fin covers were not manufactured by LESTER. They have the logo of Hoover on the inside. Hoover , from what I have been told is actually the vacuum cleaner manufacturer. I guess they had some aluminum casting ability.
Bruce B

[Tom P.]

Re: Nine Fin Valve Covers

There were were actually 3 versions of the 9-fin covers. As already mentioned, they were ONLY for the 56 model year and about the first 1/2 of the 57 model year.
The first version is commonly referred to as no-notch covers. These early versions did not have the two notches to clear the intake runners of the intake manifold and were only used on early 56 cars.
The second version had the notches for the intake runners for the remainder of 56.
The 3rd version was used on 57 cars for the first half of the 57 model year. The FI engines got got a notch in the upper fin of the left cover for clearance of the FI air meter/filter. Some people claim that this notch was first hand cut/trimmed by assembly workers, then later machined trimmed.
Of course, ALL 9-fin covers had the staggered bolt pattern and the Corvette was low script.
I have 2 pair of 9-fins covers and BOTH have the HOOVER logo cast on the under side. Also, as mentioned, the 7-fin covers seem to have been introduced about Feb 57 and they had low script. These low script covers were used up through 58 and maybe into 59. All the service replacement staggered bolt pattern 7-fin covers that I've seen (I have one pair still in the boxes that I bought from Chevy parts dept back about 70) are high script. These high script staggered, as well as the straight across covers with the casting flaw (line through the o of Corvette) were still available up until just a few years ago. At one time, they were about $25ea.
All finned alum Corvette valve covers were ONLY used on optional engines. All base, single 4bl engines (as well as the 300p/327s) got stamped steel covers. It was VERY common for owners of base engine cars to buy and install the alum covers---------------and then swear that they came from the factory with them. Ya, right!!! (actually, I can't blame them, who would want plain jane, painted steel covers??? A Corvette engine needs to "look" like a Corvette engine!)
A good friend of mine is restoring a 2x4, radio delete late 57 and has "made" a pair of low script (7-fin) staggered valve covers from service replacement high script covers. He set them up in a milling machine and milled down the high script to duplicate the low script. They look as good or better than originals.

[John H.]

Re: Nine Fin Valve Covers

Here's a photo of the Hoover logo on the inside of a pair of 7-fin staggered-hole low-script covers - also have a pair of similar high-script covers with the Hoover logo.

[David D.]

Re: Nine Fin Valve Covers

Good Stuff!

Thanks for the help.