Starts fine, runs 1 minute, goes psycho - Team Camaro Tech
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post #1 of 3 (permalink) Old Apr 2nd, 06, 09:33 AM Thread Starter
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Starts fine, runs 1 minute, goes psycho

In English: 68 with Demon carb on a 454. It starts up nice (for a cold blooded monster), starts to level off as the oil gets around, then like somone flipped a switch it starts to miss badly. Feels like a misfire @ 2+ cylinders, and smell tells me lots of unburned fuel is coming out the exhaust.

Background: I normally try to warm it up around 1500-2000 rpm, as it idles at 700 normally and won't stay running when it's cold at that level. I checked all the plugs/wires yesterday...looked good and even. All cleaned up now. Checked the coil wires and mallory rev limiter setup, seems ok. Only change in last week has been rain, but no evidence of water intrusion. Pulled cap and cleaned rotor as well, no problems.

If I take it for a drive (after stalling repeatedly) it seems to be ok above 3000 rpm, but isn't quite its normal self at lower speeds. And it stalls every chance it gets.

My brain naturally gravitates to electrical, though it is probably only because I "don't do carbs" very well. Of course, that means it will be a carb problem.

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post #2 of 3 (permalink) Old Apr 2nd, 06, 11:28 AM
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Join Date: Apr 2005
Location: Shelby MI
Posts: 51
Re: Starts fine, runs 1 minute, goes psycho

Sounds as if your floats are set to high.

As fuel pump fills bowls they overflow into intake add over richen air fuel ratio.

Should be sight plugs on side of bowls. To check have engine running and carefully open in case fuel may spill out. Level should be at or just below hole.
To adjust losen large nut on top of bowl at front and back of carb(one at a time).Turn screw until level is a corect height.
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post #3 of 3 (permalink) Old Apr 2nd, 06, 11:30 AM
David Pozzi
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Join Date: Nov 1999
Location: Central California, USA
Posts: 10,073
Re: Starts fine, runs 1 minute, goes psycho

Does it have an electric choke?
They are a pain to get adjusted right.

Does it get better after it warms up or does it stay bad?

Hand opening or closing the choke while it's running will tell you what the engine needs compared to were it is set.
With an electric choke the moment you turn on the key, the choke is heating up. so if you turn the key on, then wait 30 seconds before starting up, you get less choke than if you start up immediately.

My wife's car has the Demon and when the choke is right at idle cold, it tends to be too rich if I rev to 2000 or so. After a fiew minutes of idle, it's OK. If yours lacks enough choke at idle rpm's it may be a little too lean.

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