Engine wants to stall

[Torxhead]

When you do that compression test, inspect the spark plug burn also, there are a few spark plug charts on the net so you get some help there.

 

[Lumpy Grits]

Make sure to keep the choke and throttle plate all the way open when testing.
LG

 

[JeepCJ5]

Ok, so here are the results. I got a compression reading of 130 on the first 4 cylinders and 120 on the last two.

The spark plugs have a dry carbon coating which the charts say is carbon fouling and means the mixture is too rich or timing is over retarded.

I checked the vacuum readings again at idle. The reading at the manifold port underneath the carb (on the brake booster fitting) is the same, between 15 and 18 with the needle moving rapidly. The reading on the dist. advance port is a solid 10.

 

[Lumpy Grits]

OK-The readings are a bit low. But, they are pretty even.
You did have the throttle open-'rite'?
If it's a dry carbon on your plugs-You're run way 'rich'.
Now-squirt some oil into each cylinder and do the readings again.
LG

 

[JeepCJ5]

So I realized I failed to warm up the engine on my first try. This time I warmed it up first and then took two readings, one normal and one with a squirt of oil, making sure the choke and accelerator were fully open. Here are the results:

Cyl  Dry   Oil
1  | 140 | 140
2  | 130 | 135
3  | 140 | 140
4  | 135 | 130
5  | 130 | 130
6  | 125 | 130

Also, after the first attempt, I hit the plugs with a soft wire brush and took off the carbon. It was back after warming up the engine.

 

[JeepCJ5]

Well, I made a smoke tester with a paint can and a couple of incense sticks in order to test my exhaust. I found a leak where the exhaust manifold connects to the down pipe.

Since I had it hooked up, I went ahead and connected it to the manifold port on the intake manifold and sealed up the top of my carb. I checked several times, but I didn't see any smoke exiting anywhere.

Anybody have any suggestions for my next step? Should I take the valve cover off and take a look at my valves? I saw a video where a guy hooked up air from the compressor to the compression tester hose and pressurized the cylinders in order to find leaky valves.

A couple last questions: what is an appropriate timing goal for a AMC 258 i6 / 4.2l with no emissions equipment installed. Mine is at 9 degrees. Is that ok?

Finally: besides the idle mixture screw, is there any adjustment for overall mixture of a weber carb, or is that only adjusted with the jets? If after everything, I am still running rich, should I look at getting some smaller jets?

Thanks

 

[JR74CJ5]

I also installed the Holley fuel regulator, since I read in many places that it is needed for the Weber Carb.

The pressure gauge on the fuel regulator is jumping back and forth pretty wildly at idle. It seems to be centered around 4 psi, but when I go to adjust the regulator, it moves even more wildly going from 0 all the way above 10.

I don't remember having this problem before adding the regulator, so I plan to bypass it and see if I still have the problem, but I wanted to see if you guys have any advice.

From your first post - pressure regulation of fuel for these carbs is important. If your pressure is still jumping all over the place, I'd say you start looking into that, the pump etc.

If it's jumping up to 10 at points, that's way too high for that carb, hense the rich conditions...

Just my thoughts.

 

[JeepCJ5]

Thanks, I never posted a follow up on that. I dialed it in and I have a precise, steady 3.5 psi going into the carb.

 

[JR74CJ5]

Thanks, I never posted a follow up on that. I dialed it in and I have a precise, steady 3.5 psi going into the carb.

Ok - moving forward then... - Carry on...

 

[Torxhead]

You could look down the carb throat while it is running and look for any raw fuel dripping down or excessive spray that would give you that rich condition. Changing jets will lean out your fuel mixture, that is probably a good thing to do. Another thing that can cause a rich mixture would be a float setting to high or something stuck in the needle & seat assembly.

 

[Lumpy Grits]

What jet size do you have in now?
LG

 

[JeepCJ5]

It has the jets that come with it when bought new. I haven't opened up the carb yet. I guess that is next.

I went to the Weber website to see if the jet sizes are listed, but I didn't see them.

I did however see a big warning that recommended 2.5 psi. This is in contrast to the 3.5 that was recommended in the instructions that came with my kit. I'll try that first - look for drips as Torx recommends and then open the carb up if needed.

Thanks for some more things to look for. Is 9 degrees for timing in the ballpark?

Edit: I think I found a document that lists the jet sizes:

Mains: 145
Idle Primary: 75
Idle Secondary: 60

 

[Lumpy Grits]

9*-12* is a good start'n point.
This was done with the dizzy vacuum line disco'd and the line plugged, correct?
Also make sure you have the idle set at about 650-700rpm when the timing is set.
LG

 

[JeepCJ5]

9*-12* is a good start'n point.
This was done with the dizzy vacuum line disco'd and the line plugged, correct?
Also make sure you have the idle set at about 650-700rpm when the timing is set.
LG

Yes, line unhooked and plugged. I would guess the idle was higher than that, but I do not have a tach. I wonder if there is a line already in the harness I can hook one up to?

 

[JR74CJ5]

I would suggest we slow down a little... If you do too many things at once, then it will be really hard to tell what fixes it or makes it worse and you'll pull your hair out (unless like me you don't have any already! lol)

Timing set first. RPM's without tach is tricky, but i would adjust the idle down to where it will barely keep running and up until it levels out a bit but still has that "vromp vromp" old time sound of good running strong motor... that's probably about 600 to 750. Then try tuning the carb to this timing setting.

If all else fails and you want to see the numbers, you can do a makeshift tach from the wire off the coil, or you can pick up something like this where you can read it without cutting into any wiring...

https://www.summitracing.com/parts/ANM-CP7605/

Just mount over the number 1 plug wire I believe...

Some timing lights also show it I think? Probably the higher quality ones than I use...

from what I have read, the webber 32/36 carb is tough to adjust and tune right, but should be a good carb for you once you do...

Heres some help maybe?

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Weber CARBURETOR SET UP AND LEAN BEST IDLE ADJUSTMENT

Need help adjusting Weber 32/36 carb | BinderPlanet

https://theprojectguyblog.wordpress.com/2014/03/21/weber-carburetor-installation-on-jeep-258/

(useless info on that last one - his girlfriend looks familiar for some reason... )

Weber Set-Up and Tune Discussion - JeepForum.com - Very long thread here - easy to get lost...

Once you're sure those two things are done and completed correctly, then we should start down the internals of the engine etc...

Just my humble opinion since installing this carburetor is fairly recent...

 

[Lumpy Grits]

with all of the above post.
LG

 

[JeepCJ5]

I hear you on changing too many things at once. I guess I'm stuck on the manifold vacuum issue. I still have a wild needle in the 15-18is range. I've checked for vacuum leaks a bunch of ways, but no luck. I've tried the propane test, soapy water, and smoke which all had no results. I haven't tried the starting fluid test.

I'll keep plugging away and stop bugging you guys. It is driveable now - I just want to get it running as good as possible.

Thanks for all the suggestions!

 

[R717]

Just to be certain - is the idle smooth? If it's hunting, your vac readings will be bouncing as well. Be sure you have 12V at the choke and it's opening up.

Although its been ten years since I put my 32/36 weber on, I remember it was jetted too lean on both the primary and secondary sides. You should have an air correction jet size as well.

Try to find a friend you can borrow an afr meter from to get it dialed in.

 

[JR74CJ5]

I'll keep plugging away and stop bugging you guys. It is driveable now - I just want to get it running as good as possible.

no no - not bugging us at all, I just didn't want you to get too far into the weeds is all...

That's what the forum is for, helping - you are encouraged to keep posting what you find for sure.

Sorry for misunderstanding

 

[JeepCJ5]

Just to be certain - is the idle smooth? If it's hunting, your vac readings will be bouncing as well. Be sure you have 12V at the choke and it's opening up.

Although its been ten years since I put my 32/36 weber on, I remember it was jetted too lean on both the primary and secondary sides. You should have an air correction jet size as well.

Try to find a friend you can borrow an afr meter from to get it dialed in.

Had to look up AFR meter - pretty cool. Looks like you have to weld a bung on your exhaust though. It is idling smooth, and the choke appears to be working fine. That is interesting that your's was too lean.