need carb help

[mikewarme]

Hi Guys,

I installed a rebuilt quadrajet carb and here are my issues that didnt exist before.

Wants to die after 20 seconds in gear unless you give it throttle

Takes 15-20 seconds of cranking before it starts ( Before started right up)

Ideas?? It does have the thin metal plate under the carb

BTW 69 gmc 396 4 barrel

[geezer#99]

Choke working right!! Even in Cali you need a little choke till she warms up.

[68gmsee]

Do you have to constantly pump it while cranking?
Also, have you tried cranking while holding the pedal all the way down not pumping?

If your choke adjustments are correct go back and check the float adjustment and accelerator pump.

Remove the air breather, crank the engine for a few revolutions. Turn it off if it starts and look down the carb throat, manually activate the throttle linkage and see if it's squirting gas into the engine.

Also, insure it's not flooding. These quadrajets are known to leak from the bottom jet plugs and they had to be sealed with epoxy. You can check this by letting it sit for a while and then see if it has a heavy gasoline smell on the carb throat.

Good site about quadrajets.
http://67-72chevytrucks.com/vboard/s...d.php?t=447194

[mikewarme]

yes you r right my original carb was acctually cracked at the main jets in the body. Seems like i still have a vaccum leak since covering the snorkel on the AIR cleaner leaves it still running. Closed the mixture screws all the way and nothing changes

[GASoline71]

The throttle shaft holes are worn out. Common problem with the Q-jets. They need to be rebushed to make the seal better between the bore and the shaft.

Gary