So after more than a year of watching, a Clifford 4506 intake for the 153 showed up on Ebay and I bought it. It's been used, but looks in excellent shape. The only issue is the the little water jacket on the bottom directly below the carb mounting is missing. This seems like something I should be able to mill out of aluminum plate. Anyone have a picture of what the Clifford jacket for this manifold looks like? If not I'll just have to invent something.

Was it designed to bolt to the stock intake like the sixes? I just made a plate and TIG welded it on for the Offenhauser I modified for my 153. I added two fittings for water heat.

yes, it looks like it would just be a square shallow "dish" that bolts to the bottom. I'm wondering how deep the "dish" ought to be. I think I could get the fittings into the edge of a piece of 1" aluminum plate.

Here is what I did. This is a cut down 3x1 Offenhauser for a six. There is a cast in runner for exhaust heat that runs from the exhaust manifold connection, where the plate is, under the carb mounts. If you are running one carb in the center of the intake you could put both, in & out, heat connections in the plate. A large volume of hot water or exhaust should not be needed.

LINK

Cliffords early intakes did not generally have a water chamber like the versions that are currently sold. He sold a device, like a carb adapter, that bolted to the intake, and it had provisions for water to run through a pipe on the side of the adapter. I forget what he called them. There is one on ebay as we speak.

I used made a billet water box that was then welded to the bottom of the intakes. Or you could bolt it on. RTV and flat rubber O rings on the bolt head.