Carb help

[85ShortBedSB]

OKay so i have a 85 chevy shortbed, with a 350 crate motor, 383cam, 9:1 comp. and stock re-built quadrajet carb. Well the other day i was driving it and and i noticed that it didnt seem to have the power it usually has, i hogged on it a bit and once it slowly rounded 3k is started cuting out and back firing, only under full throttle though doesnt do it at half trottle. And it does it when you free rev it to. Now i just recently put plugs and wires and it has a new accel dist. I do have problems once and a while with the the choke not working and the fast idle getting stuck. I dont know to much aboutt carbs this is my first carb truck/car ha grew up in the wrong era. So i could use some help. Thanks in advance

[Dapper Dan]

Not exactly sure what you are trying to describe, but do you have a timing light? You might want to double check that before you start adjusting your carb.

[85ShortBedSB]

Yea that was the first thing i did, ignition timings good, it almost seems as if the secondaries arent opening.

[MTCK]

Since you said it has the problem free reving as well I think it is less likely a fuel starvation issue. Are you sure all your timing is working together properly, ie initial, vacuum and mechanical advance? I had my mechanical hanging up on a distributor and it caused nightmares upon nightmares. You could try a fuel pressure gauge inline between your pump and carb to see if the carb is getting enough pressure. If your carb is original does it have an electric choke? I cute the one off my 83 before I knew any better so I can't help you there.

[Dapper Dan]

What kind of advance do you have? like MTCK said, if it is in the higher rpm your timing might still be the problem. If it is vacuum advance check for leaks. I have a holley carb and you can check if the secondaries are opening by putting a paper clip on the shaft tight to the top and driving it. Then check to see if the paper clip moved. You might be able to do the same thing with a quadrajet, I dont know

[85ShortBedSB]

Okay so i messed with it a bit on my lunch break, had one of the older mechs that i work with take a look. choke and vacum adavanced both work, he was saying that he though the float might be bad, wel anyway i ended up just cleaning it up with carb cleaner and spraying it out a bit and putting a new air filter on. and when i left it stoped doing it, so im just gonna drive it and see if it continues, i might just invest in a new carb, its prolly about time anywa.. Any ideas on a good carb for my motor?

[MR .T]

I think its a fuel delivery issue not carb. I bet you have a pinhole in a fuel line or sending unit, possibly a pinched line. Q jets are awesome street carbs. I took mine off because the float was bad (bad float causes gas to flood out of the accelator pump) and put on an AFB edelbrock, The q jet was better when it worked IMO. If you really want a different carb Id go with an AFB.

[85ShortBedSB]

Originally Posted by MR .T

I think its a fuel delivery issue not carb. I bet you have a pinhole in a fuel line or sending unit, possibly a pinched line. Q jets are awesome street carbs. I took mine off because the float was bad (bad float causes gas to flood out of the accelator pump) and put on an AFB edelbrock, The q jet was better when it worked IMO. If you really want a different carb Id go with an AFB.

well after i read this i was working on it a bit, took the one vacuum line of that i had pluged that when to the evap can, and fuel came out so it looks like the floats bad.