'70 LT-1 cylinder head paint

[Kenneth H.]

I just started the process of cleaning my very dirty '70 LT-1 engine. Once I got some of the components (air cleaner, ignition shield, etc.) out of the way, I noticed that the surfaces of the cylinder heads between the inner edge of the valve covers and the outer edges of the intake manifold were unpainted. Actually, some of the surface is rusty, and some has a blue tint to it. I searched the archives and didn't find much, but I did find a reference to C1 paint where Dennis C. alluded to the fact that that area of the heads may not have been painted on some C1s.

The part number and casting date of the left cylinder head is correct for my LT-1 Can't see the right. Does anyone know what the finish on these surfaces should be?

Thanks,

[Terry M.]

Re: '70 LT-1 cylinder head paint

On my early 1970 they were silver, but later LT1s (where they did less hand painting) might be either silver or orange or bare. It is not a big deal. If yours rusted it might have been bare to start with.
The only reason I can think of for blue is if someone port matched the heads and intake and used blue Dychem in the process -- a rather common practice for speed shops.

[Kenneth H.]

Re: '70 LT-1 cylinder head paint

Terry,

Thanks for the info. Mine is also an early LT-1, VIN 2856. I'm not all that famaliar with engine terminology. What does "port matched the heads and intake" mean, if you don't mind explaining the term to a beginner?

Thanks,

[Terry M.]

Re: '70 LT-1 cylinder head paint

The heads and intake ports (the openings through which the air/fuel mixture passes) will not necessarily match perfectly due to production tolerances in the machining and casting operations. This can create a "lip" where the intake manifold and head meet. Throw in an intake manifold gasket that may not fit the port opening perfectly and one can have some turbulence in the intake airflow.

Since an internal combustion engine is basically and air pump, the better (read smoother and more volume) flow in and out of the engine -- the more power is produced.

Those folks who wish to increase the airflow through the intake side of the engine will grind the intake manifold and/or the intake ports at the head to match them. They will also check the placement of the intake to head gasket to be sure it fits the opening as well. Often in the process of doing this a blue dye is placed on the surfaces of the head and intake so that scribed lines will show up better. The port opening is then ground to those lines.

In the early C3 years there was no blue paint used on engines neither at the Engine Assembly plant nor at the Corvette Assembly Plant, so any blue paint had to be added sometime after assembly.

[Kenneth H.]

Re: '70 LT-1 cylinder head paint

Terry,

Thanks for the information. I do understand it better now. When I first say the blue tint (it doesn't actually look like paint), I was concerned that the cylinder heads may not have been original to the engine and had been replaced at some point.

Thanks,

[Terry M.]

Re: '70 LT-1 cylinder head paint

Dychem (a brand name) is not paint. It is a blue dye used to highlight layout lines on machined surfaces. The fluid sits on the surface and dries rather rapidly. It should clean off easily with some minor abrasion. I am not sure what the solvent is for it, but it is probably something rather strong -- like acetone. The fumes from Dychem (unless its composition has changed since I was exposed to it many years ago) are rather strong.

[Terry M.]

Re: '70 LT-1 cylinder head paint

We will have to compare notes on our cars -- mine is s/n 2161, A29 on the trim tag, so we are kind of close.

[Keith L.]

Re: '70 LT-1 cylinder head paint

It would be cool to see a spread sheet of componet dates known to be original. My LT-1 is 1586. These three are kinda close.

[Kenneth H.]

Re: '70 LT-1 cylinder head paint

Terry,

Thanks again. I'll try some abrasives to clean the area. My trim tag is B05, by the way.

Maybe we can compare notes offline at some point. I'm in the process of joining the local NCRS chapter (Delaware Valley), but I haven't been to any regional or national events yet. The only Corvette specific event that I've been to so far is "Corvettes at Carlisle".

Also, I did take your recent advice and installed a new gas tank. Everything went smoothly and I feel a lot more comfortable having the new tank in place rather than the old rusted one.

Thanks,

[Terry M.]

Re: '70 LT-1 cylinder head paint

I'm glad the new gas tank worked for you. Safety first.