1966 intake manifold on 1972 400 engine

[Ted K.]

I have a midyear Vette with wrong intake and valve covers. It is a 1972 400 cu in and I want it to look period correct. Will I have a blow by problem if the only breathing is through the oil filler tube? I will also be installing Corvette aluminum valve covers.

[Ted K.]

Re: 1966 intake manifold on 1972 400 engine

Help. Someone must have an opinion as to whether a 66 small block intake will work on a 400 engine with aluminum corvette valve covers. Will the oil filler tube be sufficient to release the blowby and not cause additional oil leaks.

[Joe L.]

Re: 1966 intake manifold on 1972 400 engine

Help. Someone must have an opinion as to whether a 66 small block intake will work on a 400 engine with aluminum corvette valve covers. Will the oil filler tube be sufficient to release the blowby and not cause additional oil leaks.

Ted------


First of all, 1966 small blocks did not use a breather type cap on the oil filler tube. However, I suppose one could be substituted.

Do I think that a breather type cap on a 1966 intake manifold mounted oil filler tube installed on a 1970+ 400 cid engine with C2 aluminum valve covers will provide adequate crankcase ventilation? I absolutely DO NOT think it will. Among other reasons, breather type caps were never installed on any Corvette engine as the sole means of crankcase ventilation.

[Ted K.]

Re: 1966 intake manifold on 1972 400 engine

If I recall the 63 had an appendage on the oil filler tube connected to the carburetor or intake to provide vacuum possibly through a pcv valve???
Not enough for blow by with a vented filler cap???
Thanks

[Duke W.]

Re: 1966 intake manifold on 1972 400 engine

The '63 oil filler tube has a nipple for a hose that connects to another nipple on the air cleaner base. This is the filtered fresh air inlet. PCV systems need a fresh air inlet and an outlet to the carb or manifold with a flow control valve that also functions as an anti-backfire device so that a backfire through the inlet won't propagate to the crankcase and cause an explosion. Crankcase vapor is mostly blowby gas that is unburned fuel air mixture, so its combustible, and the fresh air helps scavange the blowby because the valve is sized to flow more CFM than blowby CFM for a reasonably tight engine.

Duke