I've got a fresh 1961 Pontiac 389, that was originally a Single 4 Barrel . It was changed to a Tripower at some point, but several issues led me to consider installing a Dual Quad setup. There is a water passage from the existing Water pump housing into the Tripower, but none in the several Offenhauser manifolds I've seen. Is there a correct aftermarket Dual Quad Intake for this application? What year are the Offy's built for? Is there a different Water Pump housing for this application?
Pontiac went to this style pump housing/timing cover in 1964. And stayed with it thru end of production of the genuine Poncho V8. By sheer numbers, there ought to be more manifolds/choices around for this one. You could, I suppose pick up an earlier cover & associated cover to use the early style intake.
I think the number you need is an Edelbrock W25 manifold. I had one awhile back but traded it off in partial payment for a trans for my Safari.The only downside to that manifold was the heat riser port was blocked off(competition manifold).
Some of those offy manifolds used a funky special water neck and the bypass was incorporated into it and you had to tap and plug the cover.....
In 1960, Pontiac went from reverse flow/gusher cooling to conventional. So from 1960 thru 1964, the intake/pump setup looked like this. The recirculating circuit went from the front of the pump to the thermostat housing via a U-shaped tube and short coupling hose. (I think I've got my years right)
I have a nice Edelbrock P22 dual quad manifold that I believe is for the '61-'64 heads. It has a place for the bypass hose. I'll go out and take pictures. I'm thinning out my stock of stuff, it it will work for you PM me.
I have a 61 62 & 64 Pontiac and they all have the bypass on the back of the pump and go into the front of the manifold below the thermostat. I have verified the years by the stampings on the blocks. Bill
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