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PHX? 07-04-2009 06:58 PM

MC2100 problem
So i just swapped a MC2100 on and its a pain to start it up unless someone sprays carb cleaner in it and then once started it idles at 1500.. kinda like im giving it gas except im not..

What do you guys think?

Caver Dave 07-04-2009 11:56 PM


Originally Posted by PHX? (Post 1546982)
What do you guys think?

I think even the most experienced wrencher can't begin to guide you based on the info (lack of) you've provided! You may want to start by giving us the EXACTS... guessing has lost it's glamor!

- Venturi size of the 2100?
- What was done to it prior to install?
- Float level?
- Accel pump tested? Linkage in which hole?
- Adapter brand used? Bolts sealed using _____?
- Tested for vacuum leaks?

PHX? 07-05-2009 01:21 AM

1.08 with 47 jets

I hear air being sucked in some where but it sounds as if its coming from the top of the carb itself

Float was set by the carb shop I got it from three days ago and was engine tested.. got the Transdapt adapter off of summit. Besides that nothing has been done to it after it was given to me except hooked up and had the throttle linkage adapted to pull correctly.

Caver Dave 07-05-2009 01:37 PM

OK, what about the choke (electric, thermal, or manual?)... should likely be adjusted open if the ambient is above 95*. If not, wire it open temporarily.

Looking down the carb venturi (engine off & choke butterflies OPENED), are you getting a squirt of fuel from the accelerator pump when the main butterflies are thumbed open? If so, that squirt(s) should be enough to start on. If not, that's a problem...

For the "high idle", you need to confirm the butterflies are closing COMPLETELY once running.

- Is the throttle linkage holding it open? Pull it off and see...
- Have you checked/backed off the idle stop screw? (not the idle mixture screws) It's used to set the idle RPM & could be holding the throttle open.

*IF* the throttle butterflies are closing all the way, you have (at the least) a vacuum leak. (use extreme caution here!)Use some flammable carb cleaner or RRichs propane trick (harder to use without disconnecting the cooling fan as it blows around) to check for vacuum leaks around the manifold-to-adapter and the carb-to-adaptor areas. Some adaptors are uber prone to sealing issues due to the bolt spacing vs the carb flange and require additional sealant to seal completely.

PHX? 07-05-2009 03:25 PM

Ok so i just tested everything.. Starts fine (When not flooded) to top butterflies stay closed.. Im going with a vacuum leak at the base causing it to suck in gas intensely.

How could I fix the vacuum leak?

Olin18 07-06-2009 12:31 PM

Sounds like you have a vac leak. Try the propane trick to find where you are leaking. There is no point in trying to set up a carb until you know you have no vac leak.

PHX? 07-08-2009 01:56 PM

Vac leak... adapter plate bolts wouldn't allow carb to sit tightly enough.. made new ones. Carb shop redid all my vac lines and ripped out about 90% of them.

Now I go for emissions again...

Emissions test take 2!

wish me luck haha

jdoggmoney 07-08-2009 03:46 PM

I didn't respond in time but I would not bet against about half the people doing the MC2100 swap having vacuum leak issues first try. Including myself.

Here's one option if you continue to have trouble. I use the factory base plate gasket for my application, 1982 Ford E-150 van, 302 V8. This gasket is 1/8 - 3/16 thick and seals very well. Don't get me wrong, I made the mistake that caused my leak, but these thicker gaskets are a much better piece than what comes in the kits and with the adapter... IMHO. :D

PHX? 07-09-2009 12:27 AM

Passed emissions!!


So now i can drive again and my jeep had a decent upgrade done to it... Jeeps startin to come together..

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