Rough idle... engine miss problem

MyBigBlockDodge

MyBigBlockDodge

Screw it. Give me the red AND blue pills.
I'm having a problem with rough idle and/or missing, but only at idle.

Pulled the plugs and all look good except two that were darker then the rest. Put new set of plugs in, replaced plug wires to said plugs (even though the wires on it are practically new), adjust carb slightly (stuck a vacuum guage on it and set idle mixture). Fired it up and it ran great. Drive it around the block and by the time I get back the idle is lower (from about 700 to 550 in gear) and it's running rough at idle. Rev it up, and it's smooth as glass.

My thoughts... idle circuit on carb (750 vac sec Holley) or an actuall ignition issue. Secondary thought... vacuum leak?.

I've been trying to get it through emissions testing but keep failing the idle HC's (i.e. ignition problem etc).

I know there are many possiblities, but I'm looking for some ideas here to see if I'm on the right track. Ignition componants maybe?

Thanks in advance,
Adam


**update**

ok.. narrowed it down some. Carb issue from what I can tell. I sprayed some carb cleaner at the air bleeds (yeah I know should have done that before putting the new plugs in) and that seemed to help out almost immediately. Pulled the fuel level plugs and lowed the front bowl level slightly, left the rear where it was. Seems to run rough when first started after sitting so I may have a bad needle/seat, but I'm not seeing any black smoke when started or while running/reving it.

Going for a short test drive again so we'll see if it starts missing.
 
Just got back from the test drive. Seems better, but I still have a small rough idle issue. I'm going to take the carb apart and blow out all the passages and see where I stand after that. Just replaced the gaskets and power valve so it will come apart without tearing stuff up.

Hope this works. [smilie=e:

Adam
 
I finally got it... [smilie=e:

Since it was a pain to track down I knew I had more then one problem.

1) #4 cylinder plug wire boot cracked. [smilie=e: These are pretty spendy Taylor wires not more then 1 year old.

2) Fouled plug from said wire. [smilie=e:

3) Dirt in carb even though I have two fuel filters and a brand new tank/pump/lines/carb and air filter. [smilie=n:

4) Antifreeze was weak, and the temp was running around 205. Let it cool, drained some, added new and I've got a good mixture now. Temp ran about 190 - 195 after that. (ya gotta remember is 101 degrees here today).

So, it was sorta a pain, but all in all a productive - and sweaty - day.

Hope I can pass emissions on Monday morning!![smilie=e:

Adam
 
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