not quite a backfire but a burp through the carb.

78 350 pretty much stock. Just put the motor back together and when i turn the motor over i keep getting a "burp" through the carb. Not really a backfire. But just enough to spit a small mist of fuel and still not start. Gets spark and fuel but im not sure if it could be a vacuum issue or something else. Its got a stock Quadrajet and even thought im in California im not running any smog right now. Just hooking up enough to fire it up so i have a lot of hoses capped off. I wont be home for a few hundred miles so i have time to think about what i have done wrong. Anyone have any ideas they care to share?

Double check your distributor installation. verify your firing order. or,

Sounds like you might be a touch advanced, lighting the fire just a moment to soon. Try retarding the distributor just a bit. That is, turn the housing in the opposite rotation of the rotor. Just a little turn back should get you close.

I agree it sounds like the timing, to double check bring #1 up to TDC and check that the rotor is pointing too or firing #1. You did adjust the valves if unsure recheck. Thinking outside of the box for a moment it could be an intake not closing. I say this cause you indicate you just put the motor back together so I assume you had the heads off. On the other hand if an intake was the only part swapped, timing is it just sort that out and you will be golden.

X3 on what was suggested. If the firing order was off because of plug wires,I would think you would get a stronger backfire through the carb. The valve lash being a tad too tight could do that too.

I will re-drop the distributor and check firing order and plugs in the morning. You guys keep mentioning valves and its making me pucker a little. You look a few posts down and you will see that i was having issues with adjusting the valves so i had hoped nobody would bring it up. ha ha.

@Gary, you mentioned the lash being a "tad" too tight... would say 1/8 of a turn too tight all the way around be a "tad"? I went another 1/8 turn more than the procedure i choose to go with. Now im worried.

Thanks again fellers! The distributor was 180 out. Not sure how the heck i did that but i did. (senior moment). Now it fires up on the first revolution, just kind of runs like crap. With most of the ports for the carb blocked off i may have a vacuum issue. It fires and idles a little low for about 20 to 30 seconds then dies like you shut the key off. Im off to investigate further but at least it starts.