I have a 1977 F-100 with a 302 engine and an Edelbrock 500 CFM carburetor. I have an intermittent issue with the engine missing and at times stalling. This usually occurs under a load like climbing a hill or heavy acceleration. My wife was driving behind me when it happened the last time and noticed that black smoke came out of both exhaust pipes when the problem occurred. The times that it has stalled, the truck will usually restart after a few minutes but not right away. Oddly, I have found that when it begins to miss and lose power, I can shift into neutral and the engine will recover.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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The last time I had a stall, I checked the fuel line. I have a clear fuel filter with to debris and solid fuel. Fuel is also jetting into the carb when I press the accelerator.<o></o>
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I pulled the ignition module and took it to O'Riley's Auto Parts. They tested it 4 times and it passed each time. The unit did not even get warm.<o></o>
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Plugs, wires, cap and rotor are less than 2 years old and have less than 1,000 miles on them. <o></o>
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Any thoughts on what could be causing this problem?<o></o>

 

Your Carb may need to be adjusted, edelbrocks have to adjustment screws on the front of the carb, one is for air the other is for fuel, it sounds like your running rich. I don't remember which screw is which, but you can find out pretty easily if you have the manual on it, or go on to there website.

 

That's incorrect...both screws are the air\fuel mixture ratio at idle. The left is for the passenger side primary, the right is for the driver side primary. This is standard practice. Fuel mixture at other throttle positions is controlled by jet size and metering rods / power valve. This almost sounds like a float issue, especially if it happens at an incline. The black smoke makes me suspect it's not a vacuum leak.

 

Thanks for the responses. For the float, what could be the problem and how would I address? Could it be sticking (the truck sat for a long time before I bought it and it sits in storage for 5 months of the year)? Can I clean it or does it need to be adjusted or replaced?

Thank you both again for the responses!

Steve

 

take the carb off. pull the top off and go through it. pull the metering jets etc out. check the float rods where they pivot at. using a bit of emry cloth to shine them up if they are all gunked up. Just take it all apart clean it up. If you buy a carb kit for it, it comes with directions on how to adjust the floats.

 

Edelbrocks are really easy to work on. Go to their web site and download a manual for your carb. It'll cover the float adjustment you want to check. Also the air/fuel adjustment and changing metering rods and jets. You may be very rich from the black smoke description and this will require a jetting or metering rods to get it dialed in. The air/fuel screws only adjust idle mix. I had to pass CA smog with my Carter AFB and 460 and it took a couple tries on jets and metering rods to get it within spec.
Good luck.

 

Went to Edelbrock's site and downloaded the manual. When I pulled the truck into the garage, I let it warm up to operating temperature with the air cleaner off. I noticed that the choke was barely open. Followed Edelbrock's procedure to adjust the choke at op temp. Big difference in performance. I think this was my issue, it has not stalled out yet under load all weekend.

Thanks for everyone's help and for reading my post.

Steve

 

Hey Steve, thanks for coming back to update us on how you got your issue resolved. To many times this does not happen and we all never know what the out come was. This results in someone else having to repost and wait on a response to get their same issue resolved.
Thanks gain, this is what FTE is ALL about!