[Chester Copperpot]

Hi everyone, first time, long time.

Short story first:
I picked up my 62' P1800 (#2421) in early 2009 after wanting one for as long as I can remember. The car originally came with a downdraft weber which was just ok... I daily drove the car in Southern California for a few years, averaging 500 miles a week without a hiccup. I then moved to rural Northern California (not the bay area), but before I did I picked up a commuter car and put a set of DCOE 40's on Valerie (the Volvo). I love the way they sound, just incredible, but I hate the idle. I know these are more a race carb, and ideally I should be using 45's anyway.

Fast forward 2 years and I now have a complete B18 short block and a built head coming in the mail any day now. Due to my driving style I decided to switch over to a set of HS6's which arrived in the mail today via ebay with manifold ($160) and plan to have them rebuilt and rebushed, and eventually I'll sell the DCOE's.

The Question:
I acquired an aluminum intake manifold years ago, vacuum port (?) near cylinder 1, which I'm assuming is for Brake Booster. The manifold that came today has the same vacuum port (?) near cylinder 1, but it also has a port (vacuum? breather?) on the manifold bridge (?). I have a B18 with a open crankcase vent, no PCV system, and the oil cap is sealed, no nipple. So, how do I implement that port on the manifold bridge? Can I use it for vacuum advance on my 123 Distributor? Can/Should I Tee the vacuum port near cylinder 1 for both brake booster and vacuum advance? Any differences in flow between the 2 manifolds? Should I just convert to a PCV system? If so, what about an oil separator catch can?

Chester Copperpot

 

[tmtalpey]

The manifold center port is for the PCV, if your engine is an early one without a PCV, then plug the manifold.

Don't use the center port for brake vacuum, use the unrestricted front one.

Vacuum advance comes from the rear carb, just behind the throttle butterfly. If your carb doesn't have it, you'll need to modify it. But, consider replacing your distributor to a later mechanical-only one.

 

[Phil Singher]

DCOEs idle just great if they are in sync and jetted right. With any sort of performance cam, they'll idle better than SUs, which don't respond happily to more than stock overlap. With a mild-ish cam, the SUs will work just fine, perform as well, and be a lot quieter.

Manifold vacuum is manifold vacuum no matter where you tap into it. There's nothing wrong with using either port for vacuum advance, contrary to popular belief. It just means that you have vacuum advance at idle, which is not a bad thing. As soon as the throttle opens at all, the advance is exactly the same whether it's hooked to the manifold or a port on a carb just outboard of the throttle plate.