Carb question (Mc2100)

[Petescj]

I just replaced the weber on my jeep with a Mc2100. The carb works well except it doesnt seem to give me wide open throttle under load. Parked in the driveway it revs fine , just like it should. When looking down the throat of the carb and depressing the linkage fully the butterflies at the bottom of the carb only open about 1/4 of the way. The linkage itself pulls all the way back till it hits the body of the carb itself. It seems like a very short throw. I cant get more than around 45 mph up hill and if the hill is longer it steadily drops even though Im on the throttle all the way. Power Valve? I plan on putting one in tomorrow. Just wondering any other ideas?

 

[IOPort51]

I just replaced the weber on my jeep with a Mc2100. The carb works well except it doesnt seem to give me wide open throttle under load. Parked in the driveway it revs fine , just like it should. When looking down the throat of the carb and depressing the linkage fully the butterflies at the bottom of the carb only open about 1/4 of the way. The linkage itself pulls all the way back till it hits the body of the carb itself. It seems like a very short throw. I cant get more than around 45 mph up hill and if the hill is longer it steadily drops even though Im on the throttle all the way. Power Valve? I plan on putting one in tomorrow. Just wondering any other ideas?

look at the other end of the throttle shaft and see if it is hitting something on the choke control.

 

[Petescj]

Nope , doesnt seem to be binding at all. But those butterflies should be open wider than that Im thinking , No? Like straight up and down?

look at the other end of the throttle shaft and see if it is hitting something on the choke control.

 

[IOPort51]

I have one here on my desk that I have not installed yet and it opens to 90 degrees. the only thing I can see that may keep it from opening as it sets on the table is on the choke end. The only other possibility would be if it were hitting the bore of the adapter.

 

[IOPort51]

does the linkage continue to travel after the butterfly's stop??

 

[Petescj]

Already too dark to tell right now. I'll check tomorrow after work. I figured it would open that way. Could be binding on the adapter plate.

 

[dalefan88]

if that is the case, i bought a spacer for say a i think 79 ford 302. i put this on when i put my carb on and never had a problem.

 

[Petescj]

Thats right Dale I forgot about that. The one I had on my '85 had a plastic "base" with a spacer on it. This one didnt have it and I just bolted it to the adapter plate. I bet thats it. If Im thinking right they should be a little bigger even at 1.14.

 

[elwood blues]

Hey Pete, which carb do you have? The one with the choke pulloff (2100);

Or the kind without (2150);

 

[Petescj]

Without. I have the bottom pic. If you look at the linkage on that one youll see a small bump on it. That hits the body of the carb at wide open throttle. The part that sticks out where the idle screw is.

 

[Petescj]

Jeez now Im a little confused. Im pretty sure I had the top one on my other Jeep. Gonna have a talk with the guy that bought it from me at work tomorrow.

 

[elwood blues]

Without. I have the bottom pic. If you look at the linkage on that one youll see a small bump on it. That hits the body of the carb at wide open throttle. The part that sticks out where the idle screw is.

Double check. That'll make a difference weather you need the spacer or not.

I had the same problem with that part of the throttle linkage, to make it clear the manifold without using a spacer I used a dremel and a cut off wheel and cut that part off and moved the throttle cable ball.

 

[Petescj]

So that made your linkage have a longer "throw" and opened up the butterflies to the 90 degree angle? Mine isnt hitting the manifold , it actually bottoms out on the carb body

Double check. That'll make a difference weather you need the spacer or not.

I had the same problem with that part of the throttle linkage, to make it clear the manifold without using a spacer I used a dremel and a cut off wheel and cut that part off and moved the throttle cable ball.

 

[Petescj]

Filed down the linkage and it no longer bottoms out on the carb base. Still didnt help. Had to order the spacer , should be in today after work. I'll let yous know.

 

[Petescj]

Need longer carb studs.

 

[elwood blues]

You have one of these, right? The large two barrel carb to small two barrel manifold adapters, right?



To heck with carb studs, get a set of allen head bolts and countersink them into the adapter plate, then just bolt the carb through the adapter plate.

Does that make any sense, because I'm questioning myself if it does or not ?

 

[IOPort51]

You have one of these, right? The large two barrel carb to small two barrel manifold adapters, right?



To heck with carb studs, get a set of allen head bolts and countersink them into the adapter plate, then just bolt the carb through the adapter plate.

Does that make any sense, because I'm questioning myself if it does or not ?

I think that will be harder to assemble than it sounds. I would wonder if the spacer is really thick enough to requite longer studs. I don’t think I would sweat it until the spacer arrived. I don't think I would start doing creative engineering until I had it in hand.

Yes it makes sence but I don’t have one in front of me so I don’t know for sure.
I know that as I looked at the adapter I was of the opinion that it needed Allen head bolts some place to replace regular hex heads, I think.

 

[Petescj]

Kinda. The studs use these dumb little nutserts on the bottom. Im just grabbing some today from work.

You have one of these, right? The large two barrel carb to small two barrel manifold adapters, right?



To heck with carb studs, get a set of allen head bolts and countersink them into the adapter plate, then just bolt the carb through the adapter plate.

Does that make any sense, because I'm questioning myself if it does or not ?

 

[Petescj]

Yes it is. I had it in front of me when I measured.

I would wonder if the spacer is really thick enough to requite longer studs.

 

[Petescj]

Viola !! Problem solved. Full range of motion with the butterflies now that the spacer is installed. The idiot (me ) who installed the adapter plate put it on backwards. This caused the gasket to touch the butterflies and stop them. I could see the two indentations in the gasket when I took it apart. It was very minimal but just enough to hold them up. I added the spacer in since I had it. The spacer was marked "front" on the end I had in the back.