I just bought this truck and i have a few questions... What is the timing for it? Its making alot of little back fires so thats what i think should be done. Another question is what could be the cause of a high rev when warm? When it's cold it bogs down but when it gets warm it goes up to a level rpm but it seems high and it's kind of loud..
Welcome! I also have a 76' 620 and am new to this forum. Good luck with your new project.. At least these seem to be easy to work on. Troubleshooting on a 33 year old truck can be a challange, but rewarding when you fix it. Try working with your automatic choke (if it has one) that may be the cause of the idle prob..
That definately sounds like a choke problem. Pull the air cleaner and start the truck and see where your choke is at. Try moving it by hand and see if it has any effect.
