Author Topic: Newer Qjet on an older engine  (Read 1900 times)

Offline tat2krystof

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Newer Qjet on an older engine
« on: January 17, 2017, 11:01:08 AM »
Hello everyone, I'm a newbie to this forum so I apologize if this has been addressed previously, I tried the search feature but I may be using the wrong terminology.  I have a 400 engine from a 1968-69 full size Pontiac with an Edelbrock Performer Intake manifold.  I never really warmed up to the Edelbrock carbs and recently came across a Qjet #17059263 that appears to be in excellent condition, which is obviously a later model carb.  My question is, which vacuum port is which, and which ports should be plugged?  Do all remaining ports get plugged or are some of them meant to remain open?  There are no emissions equipment on my car (1973 Pontiac Lemans, Smog Exempt) and I know this carb is equipped for later model cars that had emissions equipment.

 There appears to be a vacuum line coming from the Power Brake Booster to the back of the edelbrock, one coming from the modulator from the transmission to the driver side front of the Edelbrock, and one from the vacuum advance near the distributor going to the passenger side front of the Edelbrock.  There also appears to be a thicker hose coming from underneath the intake manifold to the intake manifold itself, not sure if this gets changed with the quadrajet or if it remains as is.  Thanks in advance for the assistance. 

Offline tat2krystof

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Re: Newer Qjet on an older engine
« Reply #1 on: January 17, 2017, 11:02:38 AM »
I forgot to mention that there is currently an Edelbrock 600 Carb on the engine being used.

Offline Ethan1

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Re: Newer Qjet on an older engine
« Reply #2 on: January 17, 2017, 02:43:05 PM »
Hello everyone, I'm a newbie to this forum so I apologize if this has been addressed previously, I tried the search feature but I may be using the wrong terminology.  I have a 400 engine from a 1968-69 full size Pontiac with an Edelbrock Performer Intake manifold.  I never really warmed up to the Edelbrock carbs and recently came across a Qjet #17059263 that appears to be in excellent condition, which is obviously a later model carb.  My question is, which vacuum port is which, and which ports should be plugged?  Do all remaining ports get plugged or are some of them meant to remain open?  There are no emissions equipment on my car (1973 Pontiac Lemans, Smog Exempt) and I know this carb is equipped for later model cars that had emissions equipment.

 There appears to be a vacuum line coming from the Power Brake Booster to the back of the edelbrock, one coming from the modulator from the transmission to the driver side front of the Edelbrock, and one from the vacuum advance near the distributor going to the passenger side front of the Edelbrock.  There also appears to be a thicker hose coming from underneath the intake manifold to the intake manifold itself, not sure if this gets changed with the quadrajet or if it remains as is.  Thanks in advance for the assistance.

 I think you want the bottom-passenger side port for vacuum advance from the distributor. Not the one coming at an angle. The one under the intake is probably the PCV. That goes to the larger port on the front-middle port bottom. Back-middle port for the brake booster. And I think the one coming from the modulator will go in the front-driver's side port. The rest can be plugged off. The one on the passenger side front coming at an angle downward is for the choke pull-off. Hope that helps a little.
« Last Edit: January 17, 2017, 02:47:43 PM by Ethan1 »
Ethan

1972 Chevelle

(oo______oo)

Offline tat2krystof

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Re: Newer Qjet on an older engine
« Reply #3 on: January 17, 2017, 04:57:15 PM »
Much appreciated- thank you sir!

Offline von

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Re: Newer Qjet on an older engine
« Reply #4 on: January 18, 2017, 01:06:58 AM »
You'll need full manifold vacuum for the trans modulator. This would be any port that's pulling over about 14" of vacuum at a slow idle.

Offline tat2krystof

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Re: Newer Qjet on an older engine
« Reply #5 on: January 18, 2017, 10:49:08 AM »
Excellent, Thanks- I'll be sure to bust out the vacuum gauge to be sure- thanks again