Quadrajet rebuild problems

[perky]

Rebuilt the carb on the truck after fighting various idle troubles, and pulled intake a distributor to reseal front and rear China walls. Put it all back together, and it won't start. Tries and almost catches, but doesn't start. I'm pretty sure I did the rebuild right, doing small engine stuff regularly prior to car stuff. What's the bench setting for idle mixture screws? I documented mine prior, but reading up, that could be the problem. Any other idea that could help? Truck is a 78 c20 with a goodwrench 350, stock quadrajet. Thanks in advance.

 

[Ricko1966]

Bench idle isn't going to keep it from starting.First thing I'd verify is the distributor is in,in time.

 

[Truck82]

Rebuilt the carb on the truck after fighting various idle troubles, and pulled intake a distributor to reseal front and rear China walls. Put it all back together, and it won't start. Tries and almost catches, but doesn't start. I'm pretty sure I did the rebuild right, doing small engine stuff regularly prior to car stuff. What's the bench setting for idle mixture screws? I documented mine prior, but reading up, that could be the problem. Any other idea that could help? Truck is a 78 c20 with a goodwrench 350, stock quadrajet. Thanks in advance.

I think this should help. Had the same problem when I rebuilt my carb.

Screw the mixture screws in until they lightly contact the seat.
Back out 2 1/2 turns.
Back off the throttle/rpm screw all the way. Screw in 2 1/2 turns once it hits the linkage.

Hope this helps

 

[perky]

I think this should help. Had the same problem when I rebuilt my carb.

Screw the mixture screws in until they lightly contact the seat.
Back out 2 1/2 turns.
Back off the throttle/rpm screw all the way. Screw in 2 1/2 turns once it hits the linkage.

Hope this helps

That does help, thank you. I'll verify timing and adjust screws tomorrow, and report back. Wish I had an insulated garage

 

[mtbadbob]

Should be easy to see if it's getting/squirting fuel. If it is, I'm with Ricko on making sure distributor is in the right spot.

 

[3 Ton]

If its NOT idling, it is an idle circuit problem. Most likely debris that fell into a passage.

The only repair is to rip the bottom plate off and sonic clean the throttle body again.
Pull the adjuster screws and any pop off plugs.

 

[fast 99]

Couple of alternate methods to clean out idle passages. Using carb cleaner spray into mixture screw holes and or air pressure. Another one is crossing #5 and #7 plug wires then hitting throttle momentarily. Engine will backfire, sometimes dislodging the obstruction.

 

[Ricko1966]

Idle mixture/ idle circuit isn't going to keep it from starting. It's not even on the idle circuit on a cold start,it's on the fast idle cam,in the transition circuit and the choke plate employed.

 

[3 Ton]

I have my fast cam removed, and use a manual choke. Pull it out a 1/4 way and you have high idle.

Please dont use shortcuts, they will only make you do it over yet again.

 

[jam46]

It's more likely a timing issue than a carb issue. Double check your ignition timing.

 

[CT210]

Do you know how to static time the engine? If not pull number one spark plug and have someone bump crank engine till (Disconnect distributer first) with your finger over number one plug hole till you get compression stroke. Then put timing mark on 4 to 8 degrees before top center and remove distributer cap to see if your rotor is pointing at the number one spark plug wire.