What did I blow up now

[Rich69shortfleet]

Originally Posted by Blue GMC

No problems going up and down the rpm band while in park.

Change the fuel filter.

[garyd1961]

Old gas, water in tank?
See it quite often at work

[Ironangel]

E10 gasoline (ethanol) is breaking down when you pump it into your tank. If you live in a high humidity environment that ethanol can absorb as much as 5% water right out of the air. The shelf life of ethanol is only 90 days, phasing and separation can start taking place as soon as 14 days from the pump. A late model fuel injected motor such as the family car has a computer programed ECM that will monitor and adjust the air fuel ratio so as to compensate and maximize the burn characteristic's of said questionable fuel with little or no noticeable change in horsepower to the driver. Thats not to say that MPG's haven't gone down. In other words, what runs like crap in your 50 year old gen 1 carbureted motor will run quite well your late model fuel injected wife's car. Read this, http://www.fuel-testers.com/expirati...hanol_gas.html You dont have to "dump" the gas per se, just collect in a can and dump it into your later model vehicles tank with fresh fuel...Now with that cleared up (no pun) black smoke is not "just" an old gas issue. Gary brought up a good point about having to add an octane booster to 93 octane. Are you running trick heads with domes in that small block? I question your builder and what exactly he's done with that motor? Your describing a motor thats loading up and running extremely rich. What do the plugs look like? Somebody mentioned a sticking choke or a choke that deploys when its not supposed to. That is a viable possibility. Those Carter (Edelbrock) carburetor's can be finicky about to much fuel pressure as well as having to weak or to strong of springs in the secondary jet needles. Might try a donor or different carb off another vehicle if you can. I'm really wondering what that timing's set at with that high octane rocket fuel blend your running? Did you have detonation issues? ~Ghostrider~

[Myoldtruck]

Have you checked the rubber fuel lines, the new gas eats them up and makes them soft. I replaced mine under the truck. Also are you running a fuel regulator with that carburetor, they only like 5psi, im running the same one and had a bunch of problems when i got my truck running.

Other problems i had was intake manifold was not square when bolted up, oil fouled plugs on drivers side alot.

[RichardJ]

Black smoke comes from incomplete burn because of extremely rich fuel mixture.
I'd check for sinking float or bad float needle/seat.

You have to light the fire before you get black smoke, so I wouldn't expect an ignition problem.
A bad fuel filter is more likely to cause a lean condition.