1969 427/390 Correct Head

[Salvatore I.]

I am working through what I am being told is a porous head on a 1969 427/390hp motor. It is all original and matching numbers through the block, heads, and rest of the drive train.

I have a few questions:

1. I understand that there no "cure" for a porous head as the metal is too thin and cannot be "built up" correctly again...is that a correct understanding?

2. What is the correct head casting number for a 1969 427/390? The car was built in 12/1968. Can I find this number in the NCRS judging manual for the C-3 or is it possible that another head with a different casting number could have been placed in service on the car with that motor? (Before I open up the valve cover, I just want to be sure that I am tracking down the right head for a replacement)..........

3. Can one head be replaced without the other having to be replaced at the same time?

4. Can I get some suggestions for who might have these heads available, contact info, and a rough idea of the cost for one?

Appreciate the info and assistance....Thanks everyone!

[Joe L.]

Re: 1969 427/390 Correct Head

Sal------

1) I think what you're referring to is a term called "casting porosity". However, I've never heard of this condition affecting a GM cast iron cylinder head. I suppose it could, though. Depending upon what system in the head that the porosity affects, it might be possible to repair it. I'd check with a cylinder head specialist like American Cylinder Head repair of Oakland, CA.

2) Correct casting number is GM #3931063. These were used for 1969 oval port applications. However, they were not unique to Corvettes; they were used for all 1969 Chevrolet big block oval port applications. Oval port applications were, by far, the largest application, so these heads are not rare.

3) Absolutely YES; GM service departments used to do it all the time. It's still done today. As a matter of fact, you don't even need to replace the other cylinder head with one of the same casting number. All you need FUNCTIONALLY is one that is equivalent to the 3931063. There are several which qualify; even more if it's a passenger side cylinder head (does not require temp sender fitting). Of course, for originality purposes, if that's important to you, then you need the same casting number and correctly dated. Actually, though, I don't think that either are judged (no way to see them with the heads installed on the car). So, external configuration is the primary thing here.

[Salvatore I.]

Re: 1969 427/390 Correct Head

Thanks Joe for the input and advice.....

[Mark #28455]

063 head is cheap

Rare for an original head to leak, more likely a bad gasket or a leak at a valve guide, etc. Check first before you decide. In addition, you can likely find an original 063 head for less than $100 so is it really worth fixing yours? There were several other heads used in 1969 - the truck used a different casting, so did the 2 barrel carb 396, and they likely used some of the 1970 casting numbers later in the year - but the 063 is still quite common and readily available.
Mark