Hey I tried the search and couldn't find anything with my problem. I put an MC 2100 on my 89 YJ with a 258. When I started it up it ran at 3000 rpms. I couldn't back it down. The idle adjust screw was out. The linkage is the right length. I have no vacuum leaks. Did anyone have this problem when they switched from the POS carter BBD? And to make matters worse, those pussies on the wrangler forum on JU never did such a swap so they couldn't me...

BTW I also did the TFI upgrade and the NUTTER bypass. Could any of these have screwed things up?

Scramblin_Man

never had that problem with mine and i have no clue what it is... ask over @ http://www.partsmike.com they are the mc2100 masters

Uh...I know on mine i had to modify the linkage, and mess with the accelerator pump linkage as well (Rmeanned form Auto Zone)

Heres a pic of the linkage (I think)
Sorry 'bout the crappy pic...the stock rod for the throttle is to the right...
The shiny silver part in the center is a screw I stuck in a hole to jam the two parts of the linkage as you see them.
I inteneded that as a temp fix, and plan on welding it...but its been in there a few years now...works fine. ;)

Is the carb rebuilt?
you sure the throttle aint stuck open? I seem to recall mine sticking open for some reason during install...been a while...cant recall
MJ

ive only got expereince with 2100s on factory applications ( amc V8s) I knwo for a fact once though I had one try and get run away RPM with me on inital restart ( after a head job truck not me)

the base gasket was on backwards, giving an appropriate vac leak, had something to do with teh phenolic spacer below the carb, and teh base gasket being on backwards.

probably not much help, but its happened to me, so maybe its happeneing to you

ahhh that was it....the gasket was on backwards...it was casuign the throttle to not return to idle (butterfly things in carb hit it)

This is on a 258 with gasket, then adapter plate etc...


Knew it was something like that just couldnt remember....thanks ozark!

is ur mc2100 the 108? (450 cfm) and did you change the power valve? you should be using the #47 jets.

Originally posted by kidwired
is ur mc2100 the 108? (450 cfm) and did you change the power valve? you should be using the #47 jets.

I have had idling troubles with a Holley due to a power vavle problem. :eek:

Here is a quote from another BBS, might help.

"Just a little advice for those with MC2100 carb's adapted onto 258's and using a manual choke. The vacuum drawn through the choke mechanism should be disabled by plugging the port in the casting if you are not using the choke as originally installed on the 304. This can be done with a small amount of epoxy at either end of the port. Idle the motor with the plastic choke "pot" removed to see where this port is inside the choke casting. You will know it when you place your finger over it. It's barrel shaped and about 3/8 in diameter. Removing this intentional vacuum leak will reduce your idle rpms somewhat, and that may be desirable for some of you with too high of an idle speed. No sense drawing unfiltered air into the manifold through the choke mechanism. The original purpose of this port was to draw heated air up through the choke mechanism to assist in sensing the engine warmup. There is a threaded fitting cast on the outside of the choke casting, and this should also be plugged (a brass, rubber or vinyl cap will do), just to keep dirt from getting into the choke casting. But plugging it alone will not prevent the intentional vacuum flow that was designed into this mechanism for a purpose that is likely no longer employed."

I just hooked up my MC 2100 to my 88 today and I was wondering what did you do with the exhaust gas recirculation tubes? I plugged mine off temporarily and it would idle but I hadn't hooked up any vacuum lines to it yet and It would stall out after awhile. I think that I will take it to a shop for the final hook-up so I can give you some info on it this week.

Roadrash:eek: