MC2100 and idle problems

Collin the Hen · #1 (**permalink**) 05-06-2008, 06:48 PM

Hey, everybody. I have an 84 CJ7 with a rebuilt 258. The previous owner put in the MC2100 and it never ran well below the 1000rpm range. I took out the carby to clean and inspect it. It has now been rebuilt/cleaned at least 3 times and it'll still lope below the 1200 rpm range! And also, after it hits the 1200 rpm range or so, it runs perfectly. I hooked up a vacuum gage and it's very steady at 3 in... running! I know it's not the vacuum hose. So, could it be timed wrong, or could the ignition system be too weak or...

I'm pretty sure it's not the now spotless carby, because it is the 1.08 with 47 jets with all new gaskets and valves. I already posted this, but I'm new to Jeepz and put it in the new member forum by accident.

Any advise will be much appreciated. Sorry, kinda long.

TerryMason · #2 (**permalink**) 05-07-2008, 08:55 AM

Try pulling some spark plugs to see if it's rich or lean. I believe that you can rejet the MC2100 - you'd just have to figure out what you have and go from there.

Collin the Hen · #3 (**permalink**) 05-07-2008, 04:09 PM

It's running rich, but I don't think the jets have much to do with that, just the idle mixture screws. I turned those in so it would idle below 900. I'm thinking it may be the weak ignition system or incorrect timing. Thanks for the advice, though. Anything is appreciated!

SenorCole86 · #4 (**permalink**) 05-11-2008, 04:09 PM

I may be misunderstanding you, but you should adjust the idle mixture screws for peak rpm, then adjust the idle speed to your liking. You may have to do it a couple times, but you should not use the idle mixture screws to adjust idle speed.

Collin the Hen · #5 (**permalink**) 05-11-2008, 09:08 PM

Okay, so adjust the idle mixtures for smooth operation then set the idle down? I really need a tach to know my speed. I just took out my carb again and I found that the vacuum port for the EGR has been soldered. Is that bad? It has the nutter bypass, so no emissions stuff. I'm using the port on the passenger side for the vacuum advance, but it sounds really high pitched like an 80's TV. It does have suction, though, but it doesn't seem to run differently with the vacuum hose off, still sneezes at idle.

Thank you!