Carburator question

[Hedgehog]

My CJ has an '82 360 with a stock motorcraft 2150 Carb. The 360 runs well, but I've been having trouble getting it to idle at a consistent RPM. Sometimes it idles at ~650rpm, then it will climb to 850rpm or settle at 750rpm. The problem might be a vacuum leak. So I did a redneck vacuum leak test around the carb. with a can of carb. cleaner. Sure enough the engine stumbles when spraying around one of the throttle shaft ends. So, I called my carb. guy and he says that this is entirely normal. There is an acceptable range or % of leakage. Makes sense, the throttle needs to be able to move. What do you guys think? Only one side seems to leak and it takes a full shot right on the shaft to make the engine stumble, but it will stumble enough to almost stall.

 

[mriplaybass]

I think if you are pulling enough carb cleaner through the shaft bore to kill the engine, you have a problem. Can you feel the play if you move the shaft from front to rear, or up and down? I would just replace the bushings. They are brass, so the odds of the shaft wearing out is not as likely as the bushings. Mine is not as bad as yours, but I am having a similar problem, and this is where I plan to start. Check out this link.

Ford Motorcraft 2100 2150 2 barrel carburetor Parts Page

 

[Posi]

So, I called my carb. guy and he says that this is entirely normal.

If you have no other vacuum leaks it doesn't sound normal to me.
If the shaft area is leaking causing the engine to run bad it's not normal.
I would recommend warming the engine and get a vac reading.
Then check all hoses, intake, and carb base.
If no other leaks, your shaft, shaft bushing, or housing has excessive play.
Some options depending on what is defected,
If you have a carb specialty shop close by ( not your car guy) they can ream out the holes, put new bushings in, and ream it to the shaft size.
Look for a good shaft at the bone yard.
Buy a rebuilt carb.
Use some jb weld to build up the area that is out of spec (sanding is typically required for perfect fit).

Hope this helps.

 

[Lumpy Grits]

Sounds like your ideal mix screws are not backed out the exact same.
Screw'em both end(count turns)and back'em both out.
The idle mix adjustment may also be off-------
LG

 

[Fastatv]

Are you sure its the throttle shaft? I say this because I had a similar problem, tested a similar way and the problem ended up being base gaskets. Anyway, approx how much movement do you have in the throttle? Keep us posted on the cure.

 

[Hedgehog]

Lumpy - They did that. He says that if he leaned it out any more it wouldn't run at all.

Mriplaybass and Posi - This is a carb. specialty shop. I'm going to change my base gasket no matter what. It is set up the way I got it. 3 or 4 of those 1/4" base plate gaskets stacked up. It doesn't seem to be leaking, but looks wrong and everybody comments on it. Rob at Willys Works had the proper paper gasket, phenolic base and a 1/4" base plate gasket. Those will be installed and while doing that a close inspection of the throttle shaft will happen. I don't expect the shaft to be warn but the bushings.

A side topic. I've sold some land in upstate New York. The sale price was almost an insult, but land is cheap up there ($800/acre) and taxes are a killer. With a little money to spare the Howell Emissions legal fuel injection conversion sure looks good to me. Yes, I know it' no as advanced as the other systems, but it's been around a very long time and seems to work well.

The CJ actually does run well, but it isn't idling the way it could. I'm also getting sick of walking a tight rope with the emissions folks.

Fastatv - Was typing while you were typing. I think the answer is in this post. As written the gaskets will be changed no matter what. We sprayed the heck out of the gasket and nothing happened. Hit the shaft area and she stumbles. I'll be inspecting the shaft more closely. The carb. guys said that many garages have made a lot of money on folks by spraying a perfectly acceptable shaft /bushing and showing the owner how bad his carb. was. Honestly I just don't know where the truth is here.

 

[lutry]

I have looked at the fault analysis out of the FSM, there are a few more things
that could be looked at...
I have already seen faulty EGR and pcv valves...

 

[Lumpy Grits]

IF that carb is not leak'n air at it's base(R-YOUR NUTZ 'TITE'?)That RPM drop is a lean idle mix deal. TRUST ME
Squirt some very soapy water at the carb's base and see if it gets suck'd inside-
Back both idle mix screws out 1/8 turn and see what happens. If it's better, go 1/8 turn more and drive it some.
Also-It's not uncommon for the idle mix screws to 'walk' some after adjustment.
It would still be good to know if the idle mix screws are turn'd out the exact same. Easy to check--

LG

 

[Hedgehog]

After giving up on the front axle install today it was too difficult to stop. So, the carb came off. The proper phenolic base and gaskets went on. Nice clean and tidy, nobody will question the integrity of my carb. base gasket again. .... Well, neat except for that darned grommet that I was lucky enough to see get swallowed up by the intake manifold. It was easy enough to fish out, but I was nervous there for a little while. Also I discovered a cracked vacuum cap nicely hidden under the back of the carb. I'm so damned sick of those caps! They don't last a year! There MUST be a better way. If I'm having this problem I'm not the only one. Do you think it would work to run a vacuum hose between the two I'm having trouble with? Isn't intake manifold vacuum the same everywhere?

I also have a new PVC Valve on order.

Surprisingly enough the thing is still idling a little high.

Lumpy - I did spray some cleaner on the new base gasket to see if the engine stuttered. Did it? Nope not at all. Except for the slightly high idle the engine sure runs nicely. Hmmmm about my nuts. While over the years I've lost a few, the carb. nuts could have been tighter, but they were tight enough. They are nice and tight now, after a few miles they will be tightened again, just to make sure.

All in all it is a project done and I'm pleased about that.

 

[Torxhead]

Hedge, for those caps, I have seen them at industrial supply outfits where they come in a colored vinyl version that seem to last a lot longer than those black rubber ones. They might even be available at one of the larger home improvement stores.

 

[Hedgehog]

Torxhead - Yeah, I went crying my misery to the folks at Autozone. They pointed to those. They are thinner and brightly colored. I said what the heck and replaced all my black rubber caps with those. They can't be any worse.

Lutry - Thanks for posting. Most of those solutions have been looked at. I haven't replaced my EGR valve. Maybe it's time, the valve is more than likely as old as the engine.

 

[Lumpy Grits]

Sounds like your on the right track.

LG

 

[lutry]

Lutry - Thanks for posting. Most of those solutions have been looked at. I haven't replaced my EGR valve. Maybe it's time, the valve is more than likely as old as the engine.

I had a similar thing, changed everything with no real effect, then I decided
to have a look at the EGR valve, that looked really nice from the outside.
Well, the valve part was completely rotten...



BTW, mine was exactely the same age as the engine...

 

[Hedgehog]

Whow! All I can say is WHOW! Okay, so why is he all whow, WHOW!

As this thread started the CJ was running lean. So, the unquestionable redneck carb base gasket mess was changed out to the factory spec. set-up. While doing that a cracked vacuum cap was found and replaced with what I hope is a higher quality cap. The CJ started right up and did not react to cleaner being sprayed on the base gasket, so in theory the base gasket set up is sealed. Unfortunately the changes look far more professional, but in reality there was little difference in the way the CJ was running.


So, at Lurtry's suggestion I changed the PVC valve and the hoses. The hoses were not great and I'd planned on replacing them for years. While at it I replaced the ERG valve.

Now OMG when it's warm the engine stalls at idle, it's running to lean! To some that would be a problem. To me this is wonderful, it's been leaned out so much it SHOULD stall, the engine is running exactly the way it should. Tomorrow I'll attempt to adjust the idle mixture to where it belongs.

Lumpy and others - You might me happy to hear that my nuts are nice and tight. But putting mu nuts aside, where should I start with my low speed mixture setting. Not to worry, I'll be counting the turns to make sure both are set the same or close to it.

 

[lutry]

Here is the exact procedure...





You just have to find your specified idle rpm's and drop,
if you do not have a proper tachometer, you can do it via a vacuum
measurement as well.
If you Need more info, just post it...

 

[Lumpy Grits]

HH-Count the turns in for both idle mix screws and see if they are the EXACT same(just 'bottom' the screw out-NO more torque than that is wanted/needed).
Then back'em out the EXACT same to the starting point of one or the other screws.
How's it run'n??
If still a bit lean-Back BOTH out 1/8 turn and see what that does. If need'd back BOTH out another 1/8 turn. Is it get'n better??
Do you have a vacuum gauge?-Be a good tool here. Set to highest steady vacuum with smooth idle.
The engine must be FULLY warm'd up for this.
One other thing-You just might have to remove both screws and flush with carb cleaner their locations out.
Is this new EGR an EXACT twin to what you replaced as to port opening dia etc? Also-Is the new PCV a twin to the old one? If you reinstall the old parts and it runs 'rite'-Something is 'off' with the replacement parts.
Good luck,
LG

 

[Hedgehog]

Lumpy - The problem was that it wasn't running correctly. With an apparent vacuum leak forcing the mixture to be very lean to keep the RPMs down where they should be. ~600 RPM at idle, it wanted to idle at ~900.

The original PCV valve is identical with all new much tighter tubing. This in itself might have been a source of a vacuum leak. The new EGR valve is much different from the original. This one came supplied with various disks (10 or so) with different size holes in them. The disks are associated with the original part number. Find the original part number, use a supplied chart to find the right size disk/hole. Insert the right disk and tighten'er down. So, to make a long story short, with the vacuum leak fixed the engine SHOULD be running lean or have the idle set too low. I'm sure that setting the idle speed screw will solve the stalling issue. But I don't want to be running in an extremely lean condition, that is a bad thing.

One thing for sure is off idle the jeep has a very snappy throttle response. Different from before. It has always had plenty of power, the difference is the way it is produced. With some settings it seems to be sluggish, other times it pulls hard but isn't exactly snappy in it's response, right now it is a snappy beast, instant get up and go.

 

[Lumpy Grits]

IMO-600 RPM is just to low-I would run that idle at 750 rpm, +/- 25 rpm.
It's much better for the engine, and your put'n a good charge back into the battery.
This is done after you confirm the idle mix deal--
LG

 

[lutry]

Here are the specs for the 360 with 2bbl carb (2150):



This is at least valid for 1979, but in general there should not be a big difference during the years...

 

[Hedgehog]

Some say 500rpm, some say 650rpm, I like 650rpm, now a new number of 750 or ask much as 775rpm. But it won't pass emissions at 775rpm, oh my oh my what shall I do.

Lutry - You were typing while I was typing. Oh my now we are up to 900rpm, granted it is written in a spec. manual. At 800rpm the engine seems to be cranking right along. I don't know where I got it from, but ~650rpm seems right to me. As I think on it some, I believe that was the suggested rpm's for setting the distributor to prevent mechanical advance out of the picture.