Carburetors in general, Holley's in particular; AKA Carb Tech

**toyjeep** · 05-31-2008, 06:07 AM

Originally posted by Lindel

toyjeep, Most likely the return spring isn't quite stiff enough, or you've got some binding in the throttle plate shaft.

Thx, I will check the linkage system and try a stiffer spring and see what happens.

***HOOT*** · 05-31-2008, 11:36 PM

My carb now rests in the hands of a Holley god. He spent 1 minute scanning in his book and had the rebuild kit in his hands in under a minute. Then offered to rebuild it for me for $45. I'll let you know how it turns out.

ToyJeep,
I asked him about your idle and he suggested it may be a vacuum problem. He also said it could be the voltage on your electric choke. He was actually leaning towrds the choke voltage as the culprit.

**toyjeep** · 06-01-2008, 06:34 AM

Originally posted by HOOT

ToyJeep,
I asked him about your idle and he suggested it may be a vacuum problem. He also said it could be the voltage on your electric choke. He was actually leaning towrds the choke voltage as the culprit.

Cool, thanks for the info. I will check that out as well.

**cajun_lad** · 06-01-2008, 06:54 AM

ToyJeep, I had a similar problem with my choke. My dad (ex-mechanic and carb genius) tried adjusting the choke and couldn't get it dialed in so he bypassed it. When we rebuilt it last weekend, we noticed during reassembly that it was not assembled right from the beginning. There was no way possible that the choke would ever allow the flapper to close the way it was assembled. We took a closer look, and changed the way we assembled the choke lever (the red plastic looking piece) and voila, problem solved. I have not yet tried it cause the tranny is currently removed, but I will let you know the results as soon as it goes back together. I will also try to take some pics to show you what I am talking about, as I really don't know carb nomenclature.

**wickedwagon767** · 08-18-2008, 11:30 PM

I'm trying to decide wether or not I need to rebuild my MC 4350. I just bought the '78 Cherokee. It had to have a liberal spraying of started fluid and several attempts over a 20 minute period to get it started when I went to pick it up. Once it cranked it ran great. Cruised between 70 and 80 all the way home, about 35 miles.

I've been told the floats "get stuck" when older carbs sit for a while without being run. This one was a daily driver for a year, then was started periodically over six months until I bought it.

Any leads?

**Keman** · 08-18-2008, 11:51 PM

Originally posted by wickedwagon767

I'm trying to decide wether or not I need to rebuild my MC 4350. I just bought the '78 Cherokee. It had to have a liberal spraying of started fluid and several attempts over a 20 minute period to get it started when I went to pick it up. Once it cranked it ran great. Cruised between 70 and 80 all the way home, about 35 miles.

I've been told the floats "get stuck" when older carbs sit for a while without being run. This one was a daily driver for a year, then was started periodically over six months until I bought it.

Any leads?

Is it one with a float level view hole? Should be a bolt or screw on the side of the bowls. If it is, open the view hole and spray carb cleaner into the float bowl. That may clean enough gunk to release it.. Otherwise, get gaskets and pop off the float bowls and clean them manually. way less that a full rebuild, and should take less than a half hour.

My 2300 had just the opposite issue, the float stuck in the open position and poured gas out the top vent. I did a complete rebuild due to the 41 year age and unknown maintanence history.

**wickedwagon767** · 08-19-2008, 12:32 AM

Originally posted by Keman

Is it one with a float level view hole? Should be a bolt or screw on the side of the bowls. If it is, open the view hole and spray carb cleaner into the float bowl. That may clean enough gunk to release it.. Otherwise, get gaskets and pop off the float bowls and clean them manually. way less that a full rebuild, and should take less than a half hour.

My 2300 had just the opposite issue, the float stuck in the open position and poured gas out the top vent. I did a complete rebuild due to the 41 year age and unknown maintanence history.

I'll take a closer look for a view hole

**AMC4ME** · 10-26-2008, 09:46 PM

2100 Series
6RHA2 Model

Seems to be leaking from the accelerator pump, possibly the diaphram. Would the diaphram be an easy fix

? Is this a good carb? Jeep runs good but takes a lot of pumps to get initial start.

**Lindel** · 10-27-2008, 03:54 AM

You'll probably have to buy a complete kit to get the diaphram, but it's an easy fix on the 2150. It's on the front of the carb, and at worst it's messy. Don't do with the engine hot.

2150 is an excellent carb, especially for off-road. It's down side is that it's not very big (only around 350 cfm), and the top can warp fairly easily.

**AMC4ME** · 10-29-2008, 10:32 PM

Originally posted by Lindel

You'll probably have to buy a complete kit to get the diaphram, but it's an easy fix on the 2150. It's on the front of the carb, and at worst it's messy. Don't do with the engine hot.

2150 is an excellent carb, especially for off-road. It's down side is that it's not very big (only around 350 cfm), and the top can warp fairly easily.

My carb is a 2100 series. I replaced the diaphram but I broke one of the bolts from over tightning!!!! GRRRRRR! Its not leaking now but just knowing that it is only being held by the three bolts is driving me crazy

! I tried needle nose pliers but it can't get a grip to remove it. What should I do?

**Lindel** · 10-30-2008, 03:51 AM

You could try vise grips, or if there's a carb rebuilder near you then give them a try.

Is there enough to get a pair of vise grips on them?

**AMC4ME** · 10-30-2008, 04:34 PM

Originally posted by Lindel

You could try vise grips, or if there's a carb rebuilder near you then give them a try.

Is there enough to get a pair of vise grips on them?

Negative. It is super cold up here and I should have done this job in a warm garage. SNAP! GRRR! I have a punch list of things that need to be accomplished before she is road worthy. The carb rebuild is one of them and I'm sure that they could pull it out, hopefully. I don't even know is this carb is functioning correctly and if all parts are even there to begin with. The Jeep does start though so thats good.

A drive around the block and I can only top her out at about 25mph. I'm missing the driver side exhaust manifold down pipe. Could no back pressure do this?

**chrisnsarah** · 10-30-2008, 07:15 PM

Holley 2300 adjustments

I am curious to know when the accelerator pump arm is supposed to start moving on this carb. Is it supposed to be at the same time the throttle starts to open.

When you start out in gear or jab the accelerator quickly, it will spit or miss, then idle fine or run fine once you get moving.

I noticed the pump arm doesn't move until the throttle is partially opened. I have a spare Holley and the arm moves immediately when the throttle is moved.

There is no mention of an adjustment in the manual. Is it ust trial and error until I find a good spot? I overhauled this carb during the summer.

**Lindel** · 10-30-2008, 07:35 PM

Chris, I've always adjusted the accel pump (on a Holley) so that I can blip the throttle (in park) and it doesn't stumble or hesitate. It's always worked for me.

If you go to Holley's website, you should be able to find the initial tune up for installing it. That has all the adjustments you need to do out of the box.

AMC, on yours I don't think that back pressure (or lack of) would be your problem. It's most likely carb related, and probably a choke adjustment. It may very well be a vacuum leak, these monsters are prone to that. Look to see if the PCV hose has come off the back of the carb. If it's not vacuum, look at the choke.

**AMC4ME** · 10-30-2008, 07:47 PM

Originally posted by Lindel

Chris, I've always adjusted the accel pump (on a Holley) so that I can blip the throttle (in park) and it doesn't stumble or hesitate. It's always worked for me.

If you go to Holley's website, you should be able to find the initial tune up for installing it. That has all the adjustments you need to do out of the box.

AMC, on yours I don't think that back pressure (or lack of) would be your problem. It's most likely carb related, and probably a choke adjustment. It may very well be a vacuum leak, these monsters are prone to that. Look to see if the PCV hose has come off the back of the carb. If it's not vacuum, look at the choke.

Thanks Lindel ---

I'll check around the carb.

I've ordered a Haines manual and hopefully it will help me. Other people I spoke too also concluded that the down pipe should not make a difference. My carb is probably way out of wack. Should the butterfly valve flap open/closed when throttling? If so mine does not.......

Again I would like to get it rebuilt but I'm just trying to get the Jeep to run as best as possible with little $ down. Just to see what I have and go from there.

Carburetors in general, Holley's in particular; AKA Carb Tech

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