ok so I just got a 89 iroc z28 beginning of this month that has been converted to carb before I got her with a full msd ignition (no idea what the computer still run on the car) but anyways it runs for a few seconds like 3-5 after the key has been taken out and sometimes hear like a whistle pop from the exhaust when shut off (not normal back fire noise im used to) I know my timing is alittle off cause the po tuned it retarded to run reg pump gas ....I run premium in her though ( will correct timing when ever I can buy a gun ..never done it by ear before) but could this realy be the only cause of it continually running or would it be one of these I know the motor is running rich (strong fumes from pipes ) and the fuel pump doesn't stop making the priming noise after the cars started (constant priming sound) ..................and another question I sometimes get a knock coming from the motor at idle when in park or neutral and it goes away as soon as its put in gear im suspecting the flexplate is cracks around the bolts any thoughts ? ..........the oil pressure seems to drop a lot once the car is heated up starts at 60 and works it way down like it should but its at like 10psi at idle once hot and around 20 at highway speed I know it has a very lobe cam in it never had a cam this big before didn't know if it was the cause of the low oil pressure or just need thicker oil (think it has 10w30 now)

 

id set the timing first, then start tuning. try shutting the car off in gear and see if that stops the run-on for now.

 

You don't say how many miles on the engine?
Typical SBC specs are 10 psi / 1000 rpm with a min of 15psi @ hot idle so you are on the low side but
that would be typical of a worn engine .

What carb is on it?
Does it have a fuel reg?
Nothing to say carb is right , the floats have been set or it has been jetted correctly by the PO to suit the engine
Depending on how it is setup the fuel pump ( elec ) should be running anytime the engine is running
As stated , start by setting the timing right , then go from there

 

turned off in gear still ran

and idk how many are on the motor it has 90xxx on the od but nothings saying its turned over or been rebuilt the electric pump isn't suppose to constantly wine I know tht and idk about the regulator since its now has a carb on it where would it normally be put