Cold start concern

[a.graham52]

77 c10 with 350. Has edelbrock 500 thunderseries carb wit mannual choke.

I just got the truck out of storage. I bought the truck last may do iv never really ran it In near 0 degrees temp. Friday I set idle mixture to obtain highest idle speed/vacuum, then adjusted speed to 650. Unsure what high idle is at the moment but I keep turning it up as I go. It was fairly low.

I go out, pump pedal twice and set choke. 9/10 tones it will fire right up and run great for about 3-5 seconds, then get raspy and stall. I can repeat this many times and have to babysit the throttle to keep it running. Some times giving it throttle causes it to die.

I just put 5 gallons of fresh gas in tonight and see what it does in the morning. I never had this kind of trouble with my 85 4.3 with a 500 performer. That truck I drove year round with zero cold weather issues. Any ideas?

[rich weyand]

The float bowl could be draining down.  If I don't drive the truck for a couple days when it's cold, that happens to me.  The accelerator pump gives it enough gas when you tromp the pedal to start it, but there's no gas in the float bowl.  I crank it for about fifteen seconds with no gas pedal, then stop, tromp the pedal once or twice, and it starts right up.  It takes those fifteen seconds or so to pump gas up to the carb.  You can get rid of this by putting in an electric pump in line with the mechanical, and just turn it on for a couple seconds before you try to start it, but I've never bothered.

The float bowl might be draining down when it's cold because rubber gets hard in the cold and doesn't seal, for example.

A starting procedure you might try is just crank it for 15 seconds or so with no gas, then stop, tromp the pedal twice and turn the key.  If it starts right up and runs fine, that's the problem.

[a.graham52]

The edelbrock cannot drain because there are no seals below fuel level. With the way Temps have been, I could have issues after setting for a few hours. Once it's been warmed up, zero issues.

[jg1977c20]

are you running an open air cleaner , is there not a fast idle screw on the left side of the thunder series carbs ?
also with choke full on their should be a 1/8th " gap between choke plate and carb wall , also your idle mixture might be too lean - when you get it runing i would open up the mixture screws to get highest rpm and then give them a 1/4 turn in  idle should be around 750

[a.graham52]

I am running an open cleaner. I set mixture to highest speed like I said in the original post. Did not do qtr turn in so idle is as rich as posible. That's the wire setting in the manual. Choke is closing to 1/8".

[jg1977c20]

how about a fast idle adjustment ( this seperate from the base idle screw) you should see it on the passenger side  - engine off air cleaner off throttle wide open you can rotate the fast idle cam to get at the screw you want to have it at 1600rpm when fully warmed ( according to manual ) however i prefer around 1200 rpm - to start i would give it 1 full turn ,

the open air cleaner also gives carbbed motors a hard time in the winter cold starts - i put my stock set up back on in the winter with the exhaust heater tube so thats something to concider -been their done that

[a.graham52]

High idle is quite high, I just don'know the rpms. No tach at the moment. Luckily I still have the stuck airfilter but unfortunately I'm running headers so the stove pipe won't work anymore. I'll try swapping that out.