time setting 383

[the general]

its maybe a stupid question but how on many degris must the 1st cilinder be on my 383 stroker engine? and how to do this? it has a 650 double pumper holley on it(correctly tuned) but the real probleem is that it stays running for a second after turning the engine of i,am driving on 98 octane leadfree fuel so that cannot be the problem i think is it

 

[1985_K5_Silverado]

it stays running for a second after turning the engine off

Where do you have your idle set (at what RPM)?

 

[the general]

it runs 700rpm idle(cold)and warm 1000rpm do you mean this?

 

[1985_K5_Silverado]

it runs 700rpm idle(cold)and warm 1000rpm do you mean this?

That's exactly what I mean. 700rpm in gear, I assume. Is it set there because of a fairly radical camshaft?

With EFI, when you kill the ignition, the fuel stops instantly, but with a carb, the engine vacuum can still keep sucking gas from the idle circuit and if the engine is hot it can do the run-on thing for a second or two.

I fiddled around with idle speeds (to have the fan pulling a little more air in idle on hot days) on mine (carbed 350), and had it set at 800rpm idle in gear. I could shut it off in gear (auto trans) just fine, but it would "diesel" (run on) slightly when I shut it off in park or neutral.

At 700rpm idle in gear, it would still diesel sometimes when I shut it off in P or N.

At the factory spec 600 rpm idle in gear it would never diesel. I got the best of both worlds by using an idle compensator solenoid and when the ignition is on, it kicks the idle up to 700 rpm in gear, when the ignition is killed, so is power to the idle solenoid, and the plates are allowed to return to the ~600 rpm idle position and it doesn't diesel.

Just for the heck of it, set your idle to 600 rpm in gear (that would be ~800 rpm in P or N) and see if that stops the run-on when you shut it off.

 

[sled_dog]

Have a MSD ignitiion system? My sister's Mustang has a 6A box on it, whenever you turn it off it runs a few seconds after the key is off and even removed.

 

[the general]

yep it has a brute cam in it! but the problem was not there first,but i will trie too set the idle a little bitt lower on his rpm,s .by the way its 1000rpm(warm) in N and 700rpm(cold) in N. it has a Accel 14005 HEI in it(the gray one) it replaces the stock HEI . Taylor 409(10.4) race cables and Accel bougies , but how too sheck the ignition timing?

 

[1985_K5_Silverado]

Here is another thing that can cause dieseling in a carbureted engine: running winter-blend gasoline in warm weather, or just running gas wth ethanol contant in warm weather (neither would be a problem with FI, but with a carb, it could make a difference). Winter formulated gasoline is more volatile (has a higher vapor pressure) to aid in bitter cold weather starting and warm-up. If you've got a bunch of old gas from a winter-time fill-up in the tank of a carbed vehicle, it could be part of the problem.

Same thing with gasahol, but in your 98 octame gas, I bet there isn't any alky mixed in.

Way too much spark advance could also be doing it, as could running too lean (but you said the tune is right, so the mixture probably isn't it).