Carb or timing issue.

[gladrich]

I'm having some troubles with my engine. I have stock 302 with 4BL holley, headers and dual exhaust with flowmasters. Broncos been sitting for most of the passed six months. I have driven it a few times but not often. Started it up the other day and it was running rough and then it would just die. I found that the paper filter inside the fuel filter was loose so I changed it with a new one. There was some improvement. However now when I put the Bronco in gear the engine stalls. I have done some adjustments to the carb and I have checked the timing (10 degrees or little less). Now after it warms up the idle surges and then backs off and surges and backs off then eventually dies. I'm trying to figure out if I have a carb issue or a timing issue or something else. Advice on how to pinpoint would be welcome. Thanks!

 

[gladrich]

Went back to ground zero on carb adjustment. It was the mixture. Dummy me didn't realize there were 2 mixture screws. Live and learn ...

 

[jckkys]

The idle mixture screws on the sides of the metering block can be set to the highest RPM, to avoid the engine dying. Use 1.5 turns counter clockwise from bottoming out as a starting place. Some emissions Holleys have a reverse idle system that have aluminum labels around the screws to tell you. If adjusting the mixture isn't enough speed up the idle with idle speed screw.
If the engine ran OK before sitting, gas in the float bowls dried out and may have turned to varnish in tiny orifices like the idle feed restrictions. Holleys don't like to sit idle for long periods. Some of the gaskets warp and crack when they dry out. All this indicates a rebuild is in order. The kits have good instructions that will refresh your carburetor knowledge.