1970 c10 trouble on shut off

[Auroch]

Hey guys, when I drive my truck for a while and then proceed to shut it off, it struggles a bit to do so, runs and chugs for a few cycles before finally shutting down. Any ideas as to what this could be?
Posted via Mobile Device

[volksworld]

generally after-run is caused by combustion chamber temperatures that are so high they ignite the fuel mixture without the need of a spark...look for wrong heat range plugs, heavy carbon deposits, incorrect timing, idle speed way too high,mixture too lean,general overheating...could even be heads milled too far for the gas you're using....try premium...there were anti-diesel solenoids available that closed the throttle all he way when the power was turned off but your model shouldnt have come with (or needed) one but it could be retrofitted

[Auroch]

Originally Posted by volksworld

generally after-run is caused by combustion chamber temperatures that are so high they ignite the fuel mixture without the need of a spark...look for wrong heat range plugs, heavy carbon deposits, incorrect timing, idle speed way too high,mixture too lean,general overheating...could even be heads milled too far for the gas you're using....try premium...there were anti-diesel solenoids available that closed the throttle all he way when the power was turned off but your model shouldnt have come with (or needed) one but it could be retrofitted

Thanks man, this checklist helps a lot. I do notice it idling a bit high.

[weim55]

As Volksworld stated Throttle blade opening is key to curing this problem. You want the throttle blades as closed as possible when you shut the truck off. To cure this problem do the following : first make sure the return spring is strong enough to return the throttle blades to the idle stop screw every time you release the throttle from your foot. Second, make sure the ignition timing is set properly and not retarded. If the ignition timing is retarded it will require more throttle opening to achieve the correct idle speed. Third, adjust the idle mixture screws properly in the carburetor base. Doing all of the above then set your idle speed with the throttle blade adjusting screw. Covering all these bases will allow the throttle blades to be closed as much as possible upon shut off and should cure the problem.

Steve weim55 Colorado

[Auroch]

Originally Posted by weim55

As Volksworld stated Throttle blade opening is key to curing this problem. You want the throttle blades as closed as possible when you shut the truck off. To cure this problem do the following : first make sure the return spring is strong enough to return the throttle blades to the idle stop screw every time you release the throttle from your foot. Second, make sure the ignition timing is set properly and not retarded. If the ignition timing is retarded it will require more throttle opening to achieve the correct idle speed. Third, adjust the idle mixture screws properly in the carburetor base. Doing all of the above then set your idle speed with the throttle blade adjusting screw. Covering all these bases will allow the throttle blades to be closed as much as possible upon shut off and should cure the problem.

Steve weim55 Colorado

Crystal clear! Will follow all these steps, thanks again.