Quadrajet Hesitation When Accelerating

[jbwolfe]

Originally Posted by 68gmsee

I think you're gonna have to try what these guys are telling you otherwise it ain't gonna get fixed. Most of us speak from many, many years of experience.

First, I would look for another vacuum port if that one didn't fit or get some sort of adapter from local auto parts.

Next, I would tie the choke open regardless of what the vacuum does. It's still trying to close when the vacuum is low as when accelerating.

Re. vacuum testing: Go to Sears or the local auto parts store and pick up a vacuum gauge. It's something you need to have to work on these old trucks. One of the cheaper tools to own.

Re. checking for leaks: Yes, you can use the starter fluid carefully to see if the engine revs up higher when there's a vacuum leak. I prefer a 2-3 foot section of garden hose and place one end on the areas I suspect are leaking to listen for hissing sounds. Either way works.

Thank for your input. I'm going to order the book that was mentioned earlier to learn more about the Q-jets.

I'll tie the choke open and try that, I hadn't realized the vacuum would be lower when the throttle is open, makes sense.

Next time I'm in town I'm going to get a vac tester. I'll test the fuel pressure and vacuum. I will also test for vacuum leaks around the carb.

Originally Posted by jd7

Put a new holley on it and be done. That intake is way to much for that carb set up. A decent builder would have at least done a better job of cleaning the body.It looks to be a few carbs cannibalized.

I might if I had the money. I guess I wasn't very clear in the original post. The carb currently on the truck IS NOT REBUILT. That was the previous Q-jet, which had even more problems.