C3-'71 LT-1 Aluminum Valve Cover Oil Filler

[Robert E.]

As you may guess, I have a question regarding the aluminum valve covers on my '71 LT-1. In particular the oil filler cap. I've read that in '71, the oil filler changed to a rubber push in unit and changed back in '73 to a chrome spin on. Why have I seen so many '71's (as mine does) with chrome spin on? The serial numbers on the valve covers read:

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

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

I've read someones comments in the archives of these serial numbers being service replacements available up to 1982. Any comments??

Thanks

Robert Eisner
#41801

[Joe L.]

Re: C3-'71 LT-1 Aluminum Valve Cover Oil Filler

Robert-----

The numbers you have found cast on the underside of the valve cover indicate a later SERVICE-only valve cover. 1969 and 1970 used the twist-lock oil filler. 1971 and 1972 used the rubber push-on style, and in 1973 they went back to the 1969-70 valve cover and used it through 1977. I would not rule out the POSSIBILITY that some very early 1971 used the twist-lock or the POSSIBILITY that some very late 1972 used the twist-lock, too. However, for the vast majority, if not all, of the 1971 and 1972 model year the rubber push on was used. Incidenatlly, the original rubber push-on had the raised letter word "oil" in the center and a raised circle around the upper perimeter of the plug. Later SERVICE pieces may be different, some considerably so.

The reason why yours and so many other 71-72s have the twist-lock style is that someone changed them to rid themselves of the miserable rubber push-on style plug. These plugs harden very rapidly due to the heat of the engine and become difficult to remove and install. So, they have to be replaced regularly. You may find that your right side cover is the original, which can be determined by looking at the cast numbers on the underside. If it's the same as this one, then both sides have been replaced.

Of course, the other POSSIBILITY is that the car was not an original LT-1 and the later SERVICE valve covers were used when it was "created". If BOTH valve covers are the later SERVICE numbers, I might suspect that. However, it's also possible that both covers were replaced to make them look the same and "match".

[Robert E.]

Re: C3-'71 LT-1 Aluminum Valve Cover Oil Filler

Joe, thanks for your insight. I hope that you'd respond to my post. We can only guess why my valve covers were replaced. Most everything on my car does match and can only guess why they were replaced. I guess I'll have to look for a decent pair (another item on my list) at Carlisle. Joe, can I ask for a favor? Can you please confirm the correct casting numbers for me.

Thanks

Robert
#41801

[Joe L.]

Re: C3-'71 LT-1 Aluminum Valve Cover Oil Filler

Robert-----

The correct left side valve cover for 1971-72 Corvettes will have the following numbers and characters cast inside:

"C.B.C."

"3989005 LH"
"3965542 RH"

The right hand side valve cover will likely also have the same for most original 71s. However, it's possible that some of the earlier or, even, later 1971 LT-1s will have the 1970 right side valve cover which has the following:

"3965543 RH"
"3965544 LH"

[Robert E.]

Re: C3-'71 LT-1 Aluminum Valve Cover Oil Filler

Thanks Joe, I appreciate it.

Robert
#41801

[Joe L.]

Re: C3-'71 LT-1 Aluminum Valve Cover Oil Filler

Robert-----

The 71-72 left side LT-1 valve cover is not a particularly easy one to find. It was used only for the 71-72 model years and only for 2 applications: LT-1 Corvette and Z-28 Camaro. Also, it was sold in SERVICE only for 3 years and was discontinued in August, 1973. The PART number for this valve cover was GM #3990994. I don't think that you'll find too many NOS examples around, though.

The right side valve cover does not really matter. While there were some slight differences with respect to internal "numbering", the only real difference, externally, with respect to the 69-77 valve covers, both PRODUCTION and SERVICE, was the degree of polish.