'69 427/435 use of a lifter "valley" pan?

[Jack O.]

My '69 427/435 had an L88 intake on it when I bought it. I've since put on a '71 LS6 intake unitl I get the original 3x2 setup rebuilt. The L88 came with a separate pan that fits in the lifter valley under the intake. I believe the is OE as I have seen it pictured in original Chevrolet photos showing the L88 engine pieces. The pan would not work with the LS6 intake so I had to leave it off. Does anyone know if such a pan exists for a '69 L71 or a '71 LS6? What's the purpose of the pan?
Thanks,
Jack

[Michael H.]

Re: '69 427/435 use of a lifter "valley" pan?

My '69 427/435 had an L88 intake on it when I bought it. I've since put on a '71 LS6 intake unitl I get the original 3x2 setup rebuilt. The L88 came with a separate pan that fits in the lifter valley under the intake. I believe the is OE as I have seen it pictured in original Chevrolet photos showing the L88 engine pieces. The pan would not work with the LS6 intake so I had to leave it off. Does anyone know if such a pan exists for a '69 L71 or a '71 LS6? What's the purpose of the pan?
Thanks,
Jack

Jack,

I think the valley pan that you describe was a Chevrolet "service only" item and not original equipment on any production big blocks.
It's possible that 69 L88 had one from the factory but I don't think so.

It's purpose was to keep hot oil splash off the bottom of the intake manifold.

[Clem Z.]

Re: '69 427/435 use of a lifter "valley" pan?

My '69 427/435 had an L88 intake on it when I bought it. I've since put on a '71 LS6 intake unitl I get the original 3x2 setup rebuilt. The L88 came with a separate pan that fits in the lifter valley under the intake. I believe the is OE as I have seen it pictured in original Chevrolet photos showing the L88 engine pieces. The pan would not work with the LS6 intake so I had to leave it off. Does anyone know if such a pan exists for a '69 L71 or a '71 LS6? What's the purpose of the pan?
Thanks,
Jack

it kept the hot oil off of the bottom of the intake manifold to prevent unequal fuel distribution cause by the heating of the intake runners. i have used them on all BBC aluminum by machining off the heat riser crossover passage and welding on a aluminum plate

[Joe L.]

Re: '69 427/435 use of a lifter "valley" pan?

My '69 427/435 had an L88 intake on it when I bought it. I've since put on a '71 LS6 intake unitl I get the original 3x2 setup rebuilt. The L88 came with a separate pan that fits in the lifter valley under the intake. I believe the is OE as I have seen it pictured in original Chevrolet photos showing the L88 engine pieces. The pan would not work with the LS6 intake so I had to leave it off. Does anyone know if such a pan exists for a '69 L71 or a '71 LS6? What's the purpose of the pan?
Thanks,
Jack

Jack-----


The shield you describe was GM #3931093 and, as others have mentioned, it is for the purpose of shielding the underside of the intake manifold from hot oil. It is an EXTERNAL shield and is in not "attached" to the intake manifold. It was used in PRODUCTION but ONLY for 1969 ZL-1 (i.e. 2 Corvettes and 69 Camaros). In your case, it is undoubtedly a retrofit. The GM #3931093 shield is discontinued but replaced by GM #12555320 which is a nearly identical shield.

Most, but NOT all, Corvette engines, big block and small block alike, used an oil shield that was attached to the bottom of the intake manifold with four serrated-shaft, rivet-like pins. This included the manifolds used for 1967-71 L-71 as well as 1971 LS-6. Some exceptions included the manifolds used for L-72 and L-88. They did not use an attached oil shield. However, the 3931093 or 12555320 can be retrofitted to any application using these manifolds.

As you have found, the EXTERNAL shield will not work with an LS-6 manifold. I don't think it will work with a 68-69 L-68 or L-71 manifold, either. These manifolds originally used a "low profile" attached-type shield since the manifold extends so deeply into the lifter valley. You will note small holes in the bottom of either of these manifolds for insertion of the shield-attaching pins I described earlier (these can also be drilled and tapped for machine screws which is what I do and recommend).

I do not know of a source for the attached type shields specific for the manifolds you mentioned. However, if you wish to install one, you may be able to obtain a shield from any other big block manifold and re-work it to be usable and functional, if not "pretty". You might also try a GM #346243 shield which is still available from GM. It will require extensive re-work, too, but I think it will serve the purpose. No one will ever see it, anyway.