I'm new here, but I'll try to keep this short and to the point.
I recently ended up needing a new carburetor after I stripped the fuel filter housing bolt on a q jet for my C3. With my limited mechanical knowledge I figured best bet was to find the exact same q jet to reinstall. Found one that seemed to be a perfect fit, and after a buddy of mine made some float adjustments we thought we got it running right. I've made multiple adjustments on the mixing screws which seem to not be the problem. I even went to electric divorced choke.
The current problem is it'll start right up and idle for maybe a minute and then die out. If I start it and jump out and hold the choke valve at the right position it runs perfect. As soon as I let go though, it opens too much and dies out again.
idk if this is something to note or not, but one of the times I got it running and just kept putting it in neutral and revving to keep it from dying. While driving for about 20 minutes it sounded like it was choking and wanted to die on the drive above 30-40mph. At first I thought it was just air in the gas lines or something and would go away. But it happened enough times that I didn't think I'd make it home. Luckily got it home with that choking issue happening more frequently up until I limped it into the garage.
I'm at a loss and just about ready to take it to professionals at this point, but thought I'd look for advice here. Thanks in advance!

 

Fix your original Q-Jet by having the stripped threads repaired and have the original correctly rebuilt and set up. Sounds like the carb you bought is a real hack job, and I predict it has at least 20 issues wrong with it - drop me an e-mail for my Commercially Rebuilt Q-Jet Problems paper for a partial listing of all the things that will be wrong with the replacement carb you have.

Lars

 

Where did you get the replacement Qjet? Many/most of the remanufactured units are pretty crappy and the aftermarket offshore units, although new, are at best visually ok, but what’s inside lacks the needed precision to function appropriately. I hope you retained the original carb and didn’t use it as a core. Lars may be your best bet at restoration of the original Q-jet.

 

See if Lars will rebuild it for you? You now have 2 carbs to choose from? The original one with the stripped threads might be a better choice for rebuild. Was it just the end of the filter housing? Or where the filter housing screws in that is stripped?

 

It doesn't matter where it's stripped - anything can be properly fixed (if it's a good core).

Lars

 

Thanks for all the input. From what it sounds like, I bought what I thought to be an easy fix. Luckily I did keep the original carburetor. Didn't think that was fixable seeing as the threads to the housing are part of the carburetor, making believe I needed a whole new one. Does it matter that I tried to tap new threads before buying the new carb? I thought for sure I basically destroyed the old one.

 

As long as you have not hogged out the threads and inlet beyond the tap-drill diameter for the STI threads it can still be fixed.
Lars

 

Good to know. Looks like the original should still be salvageable

 

do as I did I like to do things my self on my 81 vette. but there comes a time when you have to ask for help. as I did when i contacted LARS. he helped me find the right carb, I paid for it and had it drop shiped to LARS. he rebuilt it sent it to me, every thing had be set up and adjusted, all i had to do was bolt it to the intake, hook up the linkage and bang it ran. do not take it to wannabe mechanics, I along with many others swear by LARS

 

welcome to the forum. there is just about all the info you will need on here to get-keep this vette alive and pretty. there are a few people on here who are the consensus experts in their field. that drunk guy leaning against the C2 in his avatar? he is THE guy for the Q-jet carb. pretty good with Holleys too... there are probably a bunch of people who can fix that carb body thread. but however good you think that carb works, it will amaze you how much better it is when you get it back from him. that is, if he has time to take your carb in.

 

Welcome to the Corvette Forum Julius74! We are glad you are here where we "speak" and "understand" (most) Corvettes!

If you have a question you will get answers here from some really amazing and experienced people like "Lars". I might still have had a Quadrajet had I heard of his skills before I started playing with Double Pumpers.
Now I would strongly suggest that you take both carburetors and send them to Lars and have him make you one that works like they did when new, or better yet one that works "better than new". He might be able to make both work and having a spare couldn't be a bad thing around an older Corvette.

When I bought my C3 there was a Quadrajet on top of the intake manifold, it gave me fits at times. I started learning as much as I could regarding carburetors. I yanked the quadrajet and gave it to my cousin for a his 1969 C3. I "understand" what you are going through, I have 5 various Holley Carburetors, all highly modified with no chokes, 1 Speed Demon 850 brand new in the box and an Avanti Custom Holley along with a Custom 850 made by the folks at AED in Richmond, VA. I understand carburetors but nowhere to the level like Lars or Jeb does. If you send Lars your parts he will send you back a pre-set carburetor that will make your Corvette "Sing with joy". Why re-invent the wheel when we have experts available to help?

I have rebuilt my last Holley as I bought a EFI system.... At least it runs in the winter easily.... Now I need to figure out what to do with my carburetor "collection"......

Use Lars and then you will become one of his happy, satisfied customers AND have no problems with your carburetors either.

Best regards,
Chris