Carb work

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
cgarb
Guru
Guru
Posts: 2005
Joined: Wed Jul 09, 2014 11:50 am
Location: Maryland

Carb work

Post by cgarb »

I have an older quick fuel 780 vacuum secondary carb that for the most part has been a great carb. I got it when the company first started when they were actually making custom carbs. I left a guy use it for a few years, we got it back my father had torn it down and replaced the gaskets like normal on all the other carbs we work on and we gave it to another friend to use because he was having carb issues. He puts it on his car and it won't idle. We just brushed it off that he did something goofy and a few months later I wanted to put it on my step brothers car. Same issue, won't idle. It act likes to me its not getting idle fuel. If you work the accelerator pumps it will keep running. That day we had it apart on 3 different occasions looking for a gasket issue or anything we could find, a blocked passage, wrong baseplate gasket something, but it left us scratching our heads. I'm just over it at this point and I'm ready for some professional help. I want to know who I can send this to that will work on other brands of carbs and test it to make sure it will run when I get it back...and also let me know what they found because it is driving me and my father nuts because we can't figure it out. I'm located in Maryland so someone that is somewhat close would be great, but I would ship it away for someone who is good at what they do for sure.
NXBOY
Pro
Pro
Posts: 201
Joined: Wed Sep 14, 2016 5:31 am
Location: MAUNIE IL.

Re: Carb work

Post by NXBOY »

Sounds like you have a blocked passage. You can actually figure out alot when disassembled by patiently blowing through each passage and comparing to other metering block to get a ruff estimate. I would try a different front metering block first maybe. should idle even with a 600 block but mixture screws would want to be out farther. New billet blocks are cheap . You probably blowed out the air bleeds in main body. Check to be sure both throttle blades are open some as well. Thats what first comes to mind, if I was betting I would guess idle mixture being plugged. Good luck, I bet you can find the trouble. :wink: Might even need to pin the restrictions, some people like to make things bigger. I apolagise if ya tried all this, just have always managed to find the ghost in my carbs , but i'm OCD lol. Goodluck either way.
Post Reply