Randomly idling rough

[JerFord]

I have an all stock 400 motor on my 78 f150. I have adjusted the carburetor per a post I found on how to tune this 2v carb using a vacuum gauge. The adjustments went as planned. But seems that when it gets warm it randomly idles rough to point of almost turning off unless I give it some gas. Normally my idle is around 600rpm and sits there steady. This rough idle happens when I come to a stop and only sometimes. Any suggestions?

Thanks


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[fatherdoug]

You might try adjusting the dashpot. It is possible the truck is returning to idle too fast, thus causing stalling?

Again refer to the carburetor manual that Duncan posted.( P.34 for the 2150 carb)

http://www.fordtruckfanatics.com/forum/showthread.php?t=33268

 

[JerFord]

Thanks that will help a lot.. It stalled once but it usually doesn't. Just idles rough and sometimes I need to give it gas for a couple seconds then it returns to normal idle.

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[BigNate]

My 351m was doing the same thing, low side idle adjustment seemed to be plugged up. Also, possible vacuum leaks. Swapped the carb and it seems much better. Mine may need more love, as I have no idea how old the distributor is, condition of the wires, or plugs, but I will soon.

One more thing is that the timing chain on mine was stretched. If you have a dwell meter you may be able to see it. I started out looking to replace the fuel pump.