What did I blow up now

[garyd1961]

Shake the truck to mix up the gas in the tank then pump some out into a clear bottle. Then let the bottle sit for about 5 minutes and see what it looks like.

[garyd1961]

Originally Posted by Rich69shortfleet

Don't bother dumping the gas. Do the other things (change the fuel filter!) first and see how things go. I've used gas that is two year old and never had a problem. Bad gas certainly wouldn't make it run bad at certain RPMs and okay at others. You may have had junk in the tank which is why you want to change the fuel filter. Oh, did I mention, change the fuel filter. Then check and snug down all the HEI connections. Also, does the HEI have a clean 12v connection? If you connected the HEI via a resistance wire or the wiring you are using is weak or not well connected, fix that right away.

What's more likely to go bad while sitting, the fuel filter, the ignition wire, or the gas? Today's gas aint what it was 20 years ago, the ethanol will draw water right out the air.

[garyd1961]

oops

[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.

[Rich69shortfleet]

Originally Posted by garyd1961

What's more likely to go bad while sitting, the fuel filter, the ignition wire, or the gas?

What's more likely to cause the engine to run poorly at specific RPMs or under load? Bad gas or a problem with the fuel filter or ignition? Six month old gas won't cause these problems.

[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.

[hjewell2]

Originally Posted by GASoline71

Seen a lot of ignition modules burn up because cats will use dielectric grease instead of heat sink grease.

Gary

you know it, they try to sell you that stuff at the counter , been using heat sink grease for years, even when you buy a new module they put that dielectric grease in there. us old cats know better.

[garyd1961]

Originally Posted by Rich69shortfleet

What's more likely to cause the engine to run poorly at specific RPMs or under load? Bad gas or a problem with the fuel filter or ignition? Six month old gas won't cause these problems.

I see it at work (Toyota dealership) a lot. Just last week had one that would run normal sitting still but would die at about 30 mph every time.
I'm not saying it has to be the gas I'm just saying before spending a lot of time and money it's an easy thing to check. Pump a little out into a clear bottle and let it sit. If it separates into two different liquids it's bad.

[GASoline71]

Originally Posted by hjewell2

you know it, they try to sell you that stuff at the counter , been using heat sink grease for years, even when you buy a new module they put that dielectric grease in there. us old cats know better.

Being old has it's benefits sometimes... lol! I had to buy the heat sink grease at Radio Shack last time I bought it.

Gary

[Rich69shortfleet]

Originally Posted by garyd1961

I see it at work (Toyota dealership) a lot. Just last week had one that would run normal sitting still but would die at about 30 mph every time.
I'm not saying it has to be the gas I'm just saying before spending a lot of time and money it's an easy thing to check. Pump a little out into a clear bottle and let it sit. If it separates into two different liquids it's bad.

Taking a test sample of the gas out and letting it settle is not a bad idea, but dumping 17 gallons of gas because it *might* be bad and probably isn't is foolish and wasteful. Do the easy, simple things first. A fuel filter costs a couple of bucks and if the engine is new not a bad thing to replace now that the engine is broken in. Checking the distributor is free other than the time spent.

And of course an engine can blow black smoke if the ignition is weak or the timing goes off regardless of whether it is running rich or lean.

If the filter is found to be clogged, it wouldn't be a bad idea to crack the carb open and clean it out, at least clean out the needle valves (or whatever Edelbrock uses, don't really like those carbs).