I need a little aspiration help

[Shawn]

So I feel like I have been cursed with a Jeep that just wont run quite right. Here are the spec's:
1986 CJ7
258 4.2
4.0 head swap
clifford intake
borla header
DUI HEI Distributor

When I bought the jeep in had a weber carb. It ran ok but failed miserably passing IM. I swapped on the Howell TBI kit and hated it because when sitting in drive the engine would pull so hard it was difficult to hold back, also when shifting from drive to park the engine would race up to 2k rpms and slowly fall back down. This made it difficult shifting from reverse to drive, when coming to a stop the jeep would almost die until the IAC would catch up. The Jeep ran great when driving and passed IM with flying colors.

Last week I bought a bran new Motorcraft 2150. The issue I'm having with this new carb is when I'm driving down the road at a steady speed the motor is stumbling, at fist I thought it was timing, vac advance, fuel mixture... I have tried everything to get rid of this stumble. I should also add, when it is stumbling if I give it light throttle it boggs until I depress the throttle so far then it takes off. Off the line it takes off just fine, under load driving up the canyon it is ok, feels like it might be lacking power, but it is the steady speed stumbling that is bugging me. At first I thought it felt like ignition, but today I think it feels more like fuel.

I'm at my wits end. Any suggestions would be very appreciated.

 

[BCGPER]

Sounds like a carburetor problem....



I'm just stepping out of the office for a couple hours, I'll get back to your PM in a bit.

 

[Shawn]

Thanks,

 

[Tacoma]

The Motorcraft 2150 is somewhat notorious among FSJ guys for being a hateful, evil carb, fitting for a Ford part. this kind of arcane witchcraft is best left to the elders though, so I'm confident BCGPER will handle this.

Vacuum ok? Got the right jets? linkage set up right? I find it useful to verify the basics when I have problems like this before I freak out at some iffy part.

 

[Shawn]

Funny, I have read nothing but great reviews on this carb. Thus the reason for buying a new one. I have never claimed to be a good card dial in kind of guy. I have been reading post on numerous threads what this and that and my problem still exists. I would have sworn by the way the TBI acted I had a vac leak,,,, but I just find that as the problem.

 

[gijohn40]

I have some time tomorrow that I could swing by and help you with this... I have an 85 cj with a holley 4bbl on the clifford manifold... I seem to have it tuned pretty good most the time...

 

[UNSTUCK]

I have bought a few kits from this guy on Ebay:

http://www.ebay.com/itm/NEW-MotorCr...Parts_Accessories&hash=item337fed3df2&vxp=mtr

I have been very happy with them. He seems to know how to set them up for out jeeps and what ever altitude you are at. You may want to contact him to see if he can give you some ideas.

I had a similar problem with one I got from him. He told me to try the different settings on the accelerator pump. I did that and didn't see any results. He then sent me a new accelerator pump and that fixed all my problems. I loved that carb on the streets. It made my cj7 run so much better. When I got on the trails, climbing a water fall was fine until I stalled it. I could never get it to start again until I rolled back down to flatter ground. Once I was down it would start right back up and run great. Another funny thing was that after I put it on I had a few guys on different occasions ask me if the Jeep ran on french fry oil. They told me my exhaust smelled just like frying french fries!

 

[Shawn]

That is the carb I bought and from that guy. I decided to pull the main jets and put some bigger ones in, it came with 47 and I have a 2100 that has some 49's in it. When I pulled the jets the threads were ruined, they were pulled apart, looks like a spring was attached to the bottom of the jet but it was the bottom threads of the jet. My guess it they were over tightened. There was also some thread debris below the jets. I tried to put the 49 jets in but they would not go, maybe different thread count, maybe the carb threads are bad. I have emailed him and waiting to hear back.

 

[UNSTUCK]

He was good about taking care of me. I'm sure he will take care of you.

 

[Shawn]

That is a really nice offer. Thanks

 

[Shawn]

Did you ever speak with him or just email?

 

[UNSTUCK]

I don't remember. My issues were back in 05 or 06. I want to say I talked to him on the phone a few times. I got tired of the waterfall issue and sold off my drive train to do a FI 350. I could run upside down after that.

 

[BCGPER]

Sorry it's taken me so long to get back with you, been a busy few days. Don't listen to Tacoma, these carbs are great for what they are. I did notice a power loss comparred to the Webber or Holley, but off road the Motorcraft shines above them.

It sounds like the issue is with that bad jet, any chance the spring under it (which shouldn't be there) was partielly blocking the opening?

The #47 jet should be plenty for a 258 I would think. I always ran #49's on my V8.

Double check your float bowl setting, and set it a touch on the high side.

Also, extend your bowl vents up as high as possible. I soldered in copper tube, then trimmed it off just below the air cleaner cover. I would think JB Weld would work here as well, but I can't verify that. This will eliminate the flooding on steep climbs issue.