Timing and mixture issues

[epeterson]

Hello,

I have a 4.2 with a new weber 2 bbl and HEI distributor. It basically runs good but I cannot get the timing anywhere near 10 Degrees BTDC. Right now its around 20 degrees BTDC. If I retard it any more it starts to idle rough. Also, the idle mixture screw seems to have no effect. The rpm does not change at all as I screw the mixture screw all the way out or in.

One more thing, I need to have the idle around 1000 or it idles VERY rough.


Eric

 

[Collin the Hen]

My Jeep did the same thing, and I learned that retarding the ignition will not cure anything. In fact, mine dieseled when I tried to shut it off.

It sounds like you have a vacuum leak. Are there any high pitched sounds like an old TV when it revs up? Make sure your vacuum lines are hooked up in the appropriate places and in good condition.

Set the ignition to 9 degrees, and tune your carb in with a vacuum gauge. The mixture screw should not be used to control the idle speed. Use your curb idle screw adjuster for that. My spark plugs were bad and that caused some rough idling.

 

[epeterson]

Thanks for the reply. I will blank off all the vacuum lines tomorrow (there are only 3) and give it as try. As of now it will not run at 9 degrees unless I put the idle up to 2000 and then it runs very rough.

I am not using the idle mixture to adjust idle rpm, but I know that the rpm is supposed to drop off at some point in the mixture screw adjustment. I just said that to give some more insight into my problem. Its hard to adjust idle mixture if the engine does not respond at all to adjustment.

I will update the post as I try things out.

Thanks again,
Eric