2100 carb conversion issue

[Gdog]

I have just converted to the 2100 carb, and when I start it, it idles so fast that I am scared to let it run longer than a few seconds. I am getting white smoke from the tailpipe. I have adjusted the idle mixture screws and it still way too fast.
I’m sure I did something wrong when I rebuilt it, but I the only thing I can think of is the power valve that came in the rebuild kit was a 7 and I saw some people used the 8.95-9.5 in their conversions, but I don’t know if this would make it run like this, or if there is something else I need to look for.
I need to set the timing, but I am scared to let it run long enough to do it.
Any help would be appreciated.

Regards,
Gdog

 

[Petescj]

I'd be looking into the linkage binding. If you just put it on look for the gasket material or plate itself interfering with the butterfly and binding.

 

[JR74CJ5]

As Pete said, probably linkage or throttle cable miss-adjusted etc.

Can you take the throttle cable off the linkage completely and start it using your hand on the linkage instead (have a buddy work the key).

If it runs better your cable needs adjusting / swaping.

It could also be a vacuum miss-hook-up...

Also what did you convert to the MC2100 from? (I forgot to look at your specs before replying...) Some "newer" jeeps had sensors you need to remove from the equation I think that affect timing and mixture etc right?

How did you do the conversion (what steps did you take / follow?)

 

[Gdog]

Thanks guys. I will look at the throttle linkage.
I had a buddy tell me today he thought it was a choke problem, but I'm not sure that would cause this.

I used several different write-ups for reference, but the installation was done based on the "MC2100 setup for AMC 258 i6 / 4.2l ", seemed to be the best I found. Attached for reference. He even mentioned making sure there was a gap when fabbing the throttle adapter.

I have an '84 CJ7 that had the Carter BBD. I believe the PO did the nutter bypass. The computer is on board, but the dizzy has new spliced wires coming out similar to the write-ups I have read on the bypass. IS there something else I need to disable to get this to work properly.

 

[Gdog]

I took the throttle linkage off, but I still get a fast idle. It was slightly better, but still way to fast for me to work on the timing. Any other ideas?
Thanks,

 

[Dan77CJ7]

I took the throttle linkage off, but I still get a fast idle. It was slightly better, but still way to fast for me to work on the timing. Any other ideas?
Thanks,

Have you adjusted the Idle speed screw down?? i ask because you havnt mentioned it, its the first thing i did when i set my timing/mixture about 400 worked, then back to normal idle speed. what vacuum ports on the mc2100 are you using? some can be block off or used. that is contingent upon your local emissions laws....

 

[Gdog]

Have you adjusted the Idle speed screw down?? i ask because you havnt mentioned it, its the first thing i did when i set my timing/mixture about 400 worked,]

Thanks, I wish I had not tried that. I must have just omitted that step. I have also adjusted the choke, fast idle and curb idle screws as low possible.

I have the PCV running to the "spacer" between the carb and the manifold. The 2100 I pulled from the slavage yard, didnt have a PCV port, but it did have a spacer with a port, so I pulled it and am using that for the PCV.
I have the timing advance from the dizzy to the ported vac below the choke.
The choke advance to port at the back of the carb. Everything else is capped.
I have all new hoses, and rechecked the connections. I dont think I have a vaccum leak, but without it running it is impossible to know for sure.

I am sure the problem is something very simple that I did wrong, but I just dont know what else to try. I am thinking about putting the old Carter back on, and taking it to the shop so an actual mechanic can look at it.

Thanks for all the help
Gdog

 

[cuban11182]

I would back the idle screw all the way out and plug all the vacuum ports on the carb, just to test. If everything is plugged, throttle is all the way loose and you still have a high idle then I'd say it's a vacuum leak.

 

[thistle3585]

I have been messing with my MC2100 for a couple weeks trying to get it going and probably took it on and off a dozen or more times. I had the exact same problem. The thing just started up and took off. It scared the out of me. I took me awhile to figure it out. I forgot to hook up the spring on the throttle arm so it wasn't returning back to idle. It was just staying open and pumping the gas just made it worse.

 

[Gdog]

Thanks guys. I will try having capping all the ports tomorrow, and see what I get. Just for clarification can I cap the PCV for this test, not sure if that will cause other issues or not.

I do have the return spring on, maybe it is not tight enough. I will play around with that tomorrow too. When you put the return spring on did it immediately fix your problem? That gives me some hope that there is something small that I can correct, and be back running.

 

[cuban11182]

You can cap everything including the PCV. Don't run it without a PCV (meaning don't take it for drives like that, but so we can solve the problem it should be fine.

 

[Bent]

Check the screw on the passenger side of the carb that sets the throttle plate opening when the choke is on. if that screw is too far in it will hold the throttle plates open even when the choke is pulled off.

 

[NorthwestCJer]

Its a vac leak at the spacer. it could be torn or cracked. spray break clean around carb and if the engine changes, its a vac leak.
Very common. Also...unhook ALL your hoses and cap ALL the ports. You do not need these things hooked up to find this problem.

Good Luck

 

[Gdog]

Thanks NW. I have added pics of the spacer and Mr. Gasket adapter as they would be on the bottom of the carb. It looks like the bottom of the PCV port is not covered. Do you think this could be the cause of the vacuum leak, or should I be looking somewhere else?

The 2100 doesn’t have a PCV port, if this is the cause is there a spacer made with a port that I can get that will provide a proper seal?

I have the carter back on, but if you think this could be the cause I will put the 2100 back on without the spacer to test it.
Thanks,

 

[Gdog]

Looks like the spacer was the issue. Took it off and no more high idle. Now to the next problem. Do I still need a spacer with a PCV port or is there somewhere I can hook my PCV up to on the carb? If I need to run the spacer how can I stop the vac leak. Is there another spacer I can get that will not cause this issue?

Any suggestions?

Thanks,

 

[Torxhead]

Running a pvc and egr system will help excessive cylinder temps down. Would it be possible for you to make your own gasket to seal off that spacer plate?

 

[JR74CJ5]

GDog,

Can you post a good photo or two of the back of your carburetor?

 

[NorthwestCJer]

http://i678.photobucket.com/albums/vv141/JeepSparky/84 cj7/DSC03302_zps2e3d7c0c.jpg

http://i678.photobucket.com/albums/vv141/JeepSparky/84 cj7/DSC03294_zps778700c4.jpg


here is mine!

 

[Gdog]

Sorry, I have been out of pocket for a couple of days. See pics attached.

As you can see I don't currently have the spacer with the PCV port installed, as that was the cause of the vac leak. I am going to a speciality store tomorrow in hopes to find another one.

I have also read in several places where others have drilled and tapped the "Dummy Hole" that you can see on the left rear of the carb, and isnstalled a 3/8" nipple for a PCV. This sounds like a good option, if it works, but since this was the only 2100 at the salavage yard, I am nervous to try that.

Let me know what you think.

 

[NorthwestCJer]

I have never seen a 2100 without that port. But I have a few of these carbs and everyone is slightly different than the next.
Sounds like you are on tract, and I would run PCV.