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.