Power Brake /PCV question

Discussion in 'The Venerable Q-Jet' started by BillBallinger, Apr 29, 2006.

  1. BillBallinger

    BillBallinger Member

    Thank you to everyone who assisted me in curing my vapor lock problem. It was a combination of things that got me to a solution, and so far so good.

    I was wondering if anyone could tell me what ports are intended for PCV and power brake on the carb itself, it being similar to a '73 350 carb? I wish to run everything through the carb if possible, to avoid leaning out any one cylinder. Does the little 1/4" port in the back of the carb supply enough vaccum for a PB booster? I have been running the PCV off of the 3/8" one in front, and the booster and modulator (this is on a "cough" Ford, I'll get another Wildcat, I promise) off of a port on the intake runner. That plug is lean. A testament to the mixture quality of the Qjet! A pig rich Autolite or Holley you would never see it.

    I could switch them of course for safety's sake, and logic would dictate so. But, I am wondering what was intender to run the PB booster and PCV originally so I can as close as possible emulate it.

    Driving a Ford, wishing I had a Wildcat!
     
  2. Nicholas Sloop

    Nicholas Sloop '08 GS Nats BSA runner up

    PCV should be the 3/8" nipple on the front of the throtle plate of the carb, and brake booster should be a fitting in the rear driver's side of the intake manifold. I do not believe that power brake vacuum was ever drawn from a port on a Q-jet. As to whether a 1/4" port on the carb COULD run the power brakes, I have no idea...
     
  3. BillBallinger

    BillBallinger Member

    Thanks

    I am thinking about drilling and tapping a 3/8" NPT fitting into the speadbore/squarebore adapter I am using to fit the carb. This way I can run a short line to the back of the carb spacer. I just hate pulling vacuum off of one runner like that.

    Would you happen to know what the orfice restriction is in the block/fitting that's in the manifold? The one I pulled out of my manifold is a brass multiple OEM Ford piece that I have found will do fine in iron, but doesn't fare well in aluminum. The orfice resrtiction for the power brake is 1/8".
     

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