Quadrajet

J

Jomeogarcia

Not-quite-so-new-guy
Jun 28, 2018
14
0
1
#1
I’m having issues with my carb. Shuts off sometimes when I stop. But after it warms up it runs fine. Any help welcomed
 

Attachments

olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
3,326
736
113
Melville,Saskatchewan
#2
Does the fast idle come on? It sounds like the choke needs adjusted. The hot air choke is tricky to set, it can only be adjusted so much or it will stay part way on. There is also a possibility of rotted tubes in the intake, hench the choke not working. Check it first thing in the morning, press the gas, there should be light tension on the choke plate. If there is, start it and see how much the choke pull off opens the choke plate. That is also adjustable and may be opening too much.
 
J

Jomeogarcia

Not-quite-so-new-guy
Jun 28, 2018
14
0
1
#4
Does the fast idle come on? It sounds like the choke needs adjusted. The hot air choke is tricky to set, it can only be adjusted so much or it will stay part way on. There is also a possibility of rotted tubes in the intake, hench the choke not working. Check it first thing in the morning, press the gas, there should be light tension on the choke plate. If there is, start it and see how much the choke pull off opens the choke plate. That is also adjustable and may be opening too much.
I’ve checked it in the morning the choke is never closed it’s always about 1/4 inch open when it warms up it opens all the way.
 
airboatgreg

airboatgreg

G-Body Guru
Oct 2, 2016
975
598
93
#7
Rule of thumb is the choke plate closes at about 75 degrees after depressing the accelerator pedal on a cold engine. May have to go a couple notches richer.
Now, depending on when it stalls it could be different things.
Does it stall immediately after start up: Not enough choke or a choke pull off issue, too much or to little. Make sure the primary pull-off holds a vacuum. Secondary pull-off if equipped will have a bleed off.
Black smoke: Too much choke , not enough pull off
Stall on first few accelerations: Not enough choke, weak accelerator pump
Stall after driving a couple minutes on a deceleration: Choke opening to fast, hot air intake not working, carboned up intake. Black smoke, to much choke.
Make sure it runs good hot, then you can work on cold drivability. EGR should only come in on a warmed up engine, it reduces oxides of nitrogen, reduces spark knock, gases take up space in the combustion chamber and improves mileage.

Pay attention to when it stalls, conditions and report back to us grasshopper
 
J

Jomeogarcia

Not-quite-so-new-guy
Jun 28, 2018
14
0
1
#8
ok so. i checked the choke plate when cold pumped the gas once and it closes all the way started it with no gas and it opened a little after five minutes i pumped the gas once and the idle went down but was rough.left it on a while longer and same thing. i disconnected the blue connector on the carb and the idle was normal and no issues. I'm thinking of just putting a holley carb in there instead of all that computer stuff.
 
MrSony

MrSony

Comic Book Super Hero
Nov 15, 2014
3,770
1,387
113
Des Moines, Iowa
#9
ok so. i checked the choke plate when cold pumped the gas once and it closes all the way started it with no gas and it opened a little after five minutes i pumped the gas once and the idle went down but was rough.left it on a while longer and same thing. i disconnected the blue connector on the carb and the idle was normal and no issues. I'm thinking of just putting a holley carb in there instead of all that computer stuff.
Don't. Sure, it will work, but the best option if you want to ditch the computer, is get a NON computer quadrajet, one from a late 70s (76-79) oldsmobile 350 or 403 would work well. I'd lean towards a 350 carb, the 403 carb as is might be a lil rich, considering it has almost 100 cubic inches on the 307 you have. Everyday Performance, Quadrajet Power, etc would set you up right. You'd also need a non computer HEI distribtor. One from a 260 olds, 350, 403, or 455 will bolt in.
 
8

81msw79

Master Mechanic
May 5, 2013
348
63
28
roselle park , nj
#10
If you go the non computer route with any carb you will also need a non computer hei distributor with a vacuum advance.
 

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