Well I have a carbed 305 in an 82 SC and when ever I turn it off in park idled at 850-900 it deisels. WTF?

I have tried everything from rotor/cap wires and plug change to taking the timing really low and running 93 octane. I have also tried using water to clean the carbon out of the engine but no carbon came out. Right now I am stuck and it is embarrasing

And the carb is a non CC rochester.

PLEASE HELP!

 

Is the motor stock? 850-900 seems high. I would shoot for more like 600-650. Also what is the base timing set at? If it's too advanced it will cause it to diesel.

 

Try shutting it off in drive then shifting to park.

 

Thats what I do. But I want it right so i can turn it off in park.

And todd like i said I have set the timing to low and it still deisels.
So do you thing it is idled to high? On the emisions sticker of the truck the carb came off of said to idle it at 850 while in park and 650 while in gear.

I am also wondering if it isn't the mixture setting on the carb. I am new to carbs so you guys might have to help me out there.

 

If it shuts down fine in drive, but diesels in park, then the idle is too high.

On the driver side of the carb, towards the front, you will see where the throttle arm is. If you look towards the upper portion of the arm while the engine is at idle, you will see the arm resting against the idle screw. Tinker with that screw and the idle will drop.



(dirty carb, I know...)

 

What did your old spark plugs look like?

 

Air: the spark plugs lookedmfine with minimal carbon build up.

Stek: Very rarely (after driving the car hard) it will deisel in drive. And if I took the idle down farther then in will be idled to low in gear.

What RPM range do your cars idle in out of gear/in gear?

 

I guess I should have mentioned this before but, before this problem occured we put on a new fuel pump and filter and my dad took both mixture screws out 1.5 turns. So what I think the problem is, is that its just running to rich at idle. but the thing that we cant figure out is which screw is for the fuel. Could someone clear this up for me.

 

Describe fine... what color were they? Also, what were they gapped to?

 

If it didn't diesel before the mixture screws were tampered with, and it does now, why not put them both 1.5 turns back in?

 

Sry guys wht I meant to say was that we took them all the way in and then took them 1.5 turns out.

Also which one is the fuel mixture screw?

 

OK guys I dont think I have a clue about carerators at this point becuase I have been doing some research And I have only been able to give my self a headache. How much would a typical mechanic charge to fully adjust my carb for me?

Do you think my carb is the problem? I know its not timing or idle speed. And my spark plugs looked normal refering to the Haynes pictures. And they are gaped at .045.