I have an inline 6 cyl. 250 engine with dual Carter Weber carbs on an aluminum Offenhauser intake manifold. I need to do two things: 1.) add a PCV valve and 2.) run the power brake booster vacuum hose. I don’t know where to connect the hoses on the engine or intake manifold. The Offenhauser intake has 2 hole on the side toward the firewall. Are those what I need to use? (See the picture below) Need help please! Suggestions and pictures welcome. Thanks. Glenn
Is the engine in running condition yet? The larger of the two holes in the photo is probably the one you need to use, but it's difficult to tell because the entire manifold is not in the picture. The smaller port lower on the casting is probably a passageway for coolant used to provide (not enough) heat to the manifold. It won't be able to provide any vacuum.
Now- - - -with two carbs, it's very unlikely the manifold will have enough vacuum to support a PCV valve and power brakes all of the time. I'd strongly suggest installing a vacuum reservoir tank with a one-way valve between the tank and the manifold, and attaching the booster vacuum line to the reservoir. That will give you one or two brake applications even when the manifold vacuum is so low that it can't operate the booster effectively. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Agree w/HRL, the big hole looks to be tapped into the intake's fuel/air plenum, you should be able to either shine a light into it and see the inside of the runner or poke a soft prod around to determine it's in the air plenum. The small hole looks to be the hot water tap into the much smaller & separate heat chamber below the fuel/air plenum. Vacuum will be present in the fuel/air plenum and not in the heat chamber. If you have vacuum in the heat chamber your intake manifold is bad.....
Another note on bridging a PCV and vacuum wipers together. The size of the PCV (amount of vacuum it passes) has everything to do with whether the wipers will work. Size the PCV too big and the wipers no workie. The PCV has to pass enough vacuum to be effective yet not steal so much of the vacuum that theres not enough to operate the wipers. Dual carbs add's to the complexity. You will probably have some trial and error before you get a good combination and as HRL suggested a vacuum reservoir will probably be necessary. I ran a PCV on my now retired 216 with vacuum wipers for several years without problem but it was a single carb. It can be done. Good luck Dave
