Beginners Advice to the Quadrajet

Grumpy Grizzly

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Hmmm....

Q-jets are awesome carbs but they are the most finicky. I will say after the rebuild I don't have to stuff my toes into the engine compartment to get it to go 50 up a hill, so I would say an overall win there.
 

Georgeb

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I have had some carters that were finicy SOBs too. And I got no time for a holly. My edlbrock ran great but only after a bit of tuning. Still love my Q-jet more than any of them.
 

Grumpy Grizzly

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I have had some carters that were finicy SOBs too. And I got no time for a holly. My edlbrock ran great but only after a bit of tuning. Still love my Q-jet more than any of them.

I would say they all have their place but the q-jet is the beast imho even if it's a bummer getting going.

If your going / have to go carb for off-roading its the only one to go with.
 

Quadrajet Power

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You can bend it. Which means your metering will always be out to lunch. Or pull it apart into 2 pieces. Which leaves you with a non working carb. You can also wreck the plastic compression seal that holds it in the bore. Again then you have a carb that is only good for parts.

I have never been able to find that part for sale anywhere. So if you wreck it your carb becomes spare parts


I agree. Best to let it eject itself. I always use a new retainer for the power piston. I also use new spring, primary rods and jets.

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Georgeb

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So how quickly should the vacuum choke pull off on my Qjet move when the throttle is opened and the vacuum dropps? I removed the linkage from the pulloff to the secondary upper plates and adjusted the spring tension to reduce the "bog" but I would like to use the linkage as intended. I think the vacuum pull off is slow to react and wont let the secondarys open. Thats why I removed the linkage in the first place.
Perhaps @Quadrajet Power can answer this...
 
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Quadrajet Power

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So how quickly should the vacuum choke pull off on my Qjet move when the throttle is opened and the vacuum dropps? I removed the linkage from the pulloff to the secondary upper plates and adjusted the spring tension to reduce the "bog" but I would like to use the linkage as intended. I think the vacuum pull off is slow to react and wont let the secondarys open. Thats why I removed the linkage in the first place.
Perhaps @Quadrajet Power can answer this...

Should take about 2 seconds or so for it to release all the way. The quickness of the release depends on driving style. I like to race, so I want mine to release faster.

Depending on your quadrajet, and the type of release, they can be modified for quicker release usually. Is yours metal at the front of the carb, or plastic?
 

Georgeb

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Should take about 2 seconds or so for it to release all the way. The quickness of the release depends on driving style. I like to race, so I want mine to release faster.

Depending on your quadrajet, and the type of release, they can be modified for quicker release usually. Is yours metal at the front of the carb, or plastic?

Mine is metal. Should be original to 1978.
 

Georgeb

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Still interested to know about the modification to the vacuum pull off.....
 

Quadrajet Power

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Still interested to know about the modification to the vacuum pull off.....

If it is too slow, you want to enlarge the port that is usually in the base of the vacuum tube of the pull off. If your vacuum tube is curved, you could heat it up to bend it to open the port slightly, or cut the tube and connect the hose to it.
 

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If it pours gas out of the top past the upper seal it's likely

A- a stuck float or dirt trapped at the needle/seat

B- an incorrect float height set after a rebuild or high float height in combo with truck sitting on an angle causing the high amount in the bowl to go over from the angle.

C- a bad fuel pump or failing fuel pump. Wrong fuel pump that is putting out too much psi causing the needle/seat to stay open causing the flooding. This is a very common one. If you have an Airtex pump you likely need a regulator. I may do a write up on mechanical fuel pumps tonight as it's been on my mind. The Airtex are know for either failing or putting out 9-12 psi which will cause the needle issue. Quads and other carbs are sensitive to the higher psi. 4-6 psi is good but 8-12 is not recommended. If you do have higher psi thru testing get a regulator or try a new pump.

Also attached is a basic ID chart
 

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