I finally decided to take on the stalling problem I've had with my 87 and it's Weber 3236 since owning it.  I found this reference and a few others that are basically the same:  http://board.marlincrawler.com/index.php?topic=46859.0

Every reference to the fix above that I can find seems to swear that it works good.

It talks about filling a breather hole in the bowl, adding an additional breather and installing a fuel pressure regulator set to 2psi.  (I'm sure everyone with a Weber is familiar with the fix.)  I did it all.  Idles and runs good except the engine seems to starve for fuel and misfires terribly on heavy acceleration.  (At least that's what I think is happening.)  The regulator is adjustable from 1 to 6 psi and opening it up doesn't seem to help.  Any ideas would be appreciated.  As soon as temperatures get above zero I will pull the gauge and regulator out of the line to see if they are causing the problem but in the mean time I wonder if anyone has any experience with this carb and mod.

Off to the Moab Easter Jeep Safari next month and I'd sure like to make this thing climb better before then. 

Thanks in advance

Don't Drill your carb YET!!
Mine had new mods from factory on a 2010 version for venting
Here is a few things to check;
*Did you cap close off all vacuum ports in the change over
*Is the distributor advance hooked up to the correct port
*Are spark plugs fresh or cleaned and gapped

Now to check a Weber for lean/rich;
Let it idle up to operating temp,
make sure coke is open and not on High Idle
Back off Idle Screw completely, now AFTER the screw touches, turn in 1 1/4turns
Set the Idle Mix Screw at 1 3/4 turn out.
If you have to turn Mix Screw out more than 2 1/2 turns
and /or turn the Idle Speed screw in more than 1 1/2 turns
you are running lean.
VERY IMPORTANT !!! Turning Idle Speed Screw more than 1 1/2 turns opens the
throttle plate past another port allowing more fuel in, and and screws up idle circuit
More help is at www.carburetion.com Weber Adjustments

George,
It almost sounds like the carb fuel bowl is being pressurized due to a lack of venting to the atmosphere. That is, the fuel bowl is fuel of air, so only a small amount of fuel can be input into the bowl, hence the starvation.  Are you sure that the new bowl breather is sufficiently venting the bowl? 

I think they best route I have seen to fix the bowl overflow/breather problem is to place a small copper tube, that extends to the top of airfilter, in the vent area.  (You could also use a Holly J-shaped vent, dumping it over the primary venturi)  Then fill the rest of the vent area with a gas resistant epoxy.  Therefore, the vent will now be extended about an inch higher.

Capt,
I am curious as to what vent changes have been made to the new Weber carbs.   Please post some pictures if you can.

Capt, Jonny
Thanks for the input.  That drilling out of the spare port the mod talked about didn't have to be done.  When I pulled the carb apart I noticed that was already done.  Looked more like a factory job than an a mod someone did though.  It was a single larger hole  and the brass fitting and tube to the canister were already in place so the only thing I did was epoxy the 1/4 inch by 3/4 vent at the top of the bowl above the floats.  The mod also talked about lowering the floats.  I didn't do that either because they were already real low when compared to specs I found on line that said something about them being parallel with the top of the carb.  The carb has been on the Sammi since I purchased it so I didn't have to do anything about plugging up the vacuum lines either although I did double check them all. 

After further troubleshooting I'm starting to think it is running rich instead of lean because if I pull a vacuum line, specifically the one running to the hot/cold air valve on the air cleaner it straightens out a lot although still not right.  That is telling me that if adding air (from the removed vacuum line) makes it run better I'm need to look at re-jetting. 

Another thing I did to it that I hadn't mentioned is replace the gasket between the carb body and the top plate and heli-coiled those bolt threads cause none of them tightened and the top plate was pretty sloppy.  I'm thinking that it might have been originally jetted with that loose top plate so it was getting air through there at the time it was jetted.  Now that is tightened it's only getting air through where it is supposed to.  Thoughts on this?  Currently the primary jet is 140, secondary is 145.  Air jets are 180 & 200 respectively.  I have a spare 135 so I'll try using that to make it primary 135, secondary 140 and see if that helps.  I run this at pretty high altitude (Colorado), sometimes up to 13 or 14 thousand feet or so.  Any thoughts on jetting that might be close for that altitude?  Johnny, I know you have run up here cause I rode with you around Taylor Park a couple years back.  You don't happen to be running a Weber 32/36 do you?  How is yours jetted?  (Thanks for sending me that shirt by the way.)

Ok, that irritates me.  I broke down this morning and took it to a carburetor repair garage.  I mistakenly thought they were supposed to know what they were doing.   Idles good.  Any heavy acceleration and it stumbles all over itself. 

Post some pictures of your vent mod.  A lot of times this vent rerouting style (routing the vent back to the fuel tank) is not sufficient as the carb fuel bowl is not open to atmosphere.  I think the most effective vent mod is to simply extend the existing vent to the top of the filter housing.  That is, adding an inch or so to the air horn vent via a copper tube. 

Another thing it could be is that your float is set too low.  Therefore, the carb is running out of fuel when you stomp on the accelerator.

The primary jet sound a little high from what I remember.  I think I ran a 120 in the primary and a 140 or so in the secondary.  That was at 1,000ft above sea level.

Finally, the other issue with the Weber carb venting is the air horn-carb base gasket.  I believe that many of the factory gaskets do not seal off the bowl vent-air correction jet area.  That is, there isn't any gasket material there.  Thus, gas can flow between the gap between the two metal surfaces despite the vent being extended.  Aftermarket gaskets are sold on ebay that address this issue. 

Good luck!

 

Jonny,
I will apologize on some of the mod statements.
Mine does have a factory vent fitting to the charcoal canister.
But it still has the large opening vent on the bowl side. in front of the
air horn by the choke plates.
In looking down thru this opening you can see the jets in the bottom of the float
bowl, and also the Air Restrictor jets which on an EXTREME angle could allow fuel
to flood the Air Restrictor jets. But with the plastic float, and the limited float swing,
acting like a micro switch, you are almost in the Space Shuttle Launch Angle.
Again, mine is a Trails / Exploring Rig, which I have had at some good climbs in the past with no flooding problems.

I recently installed a Weber on a trail Samurai, but I do not know when the carb was manufactured.  The casting was a little bit different than my other Webers, as it had a taller air horn section.  It also came with the plastic float.  Therefore, it might be one of the "2010"  model that is modified.

I was expecting that I would need to mod it to run at high angles, but when I took it to the local trails, it ran up the hills without any flooding.  I was very happy with its hill climbing performance.  Please keep in mind these hills are not anywhere near as steep as Moab though.

However, I also installed the aftermarket gasket that I mentioned earlier in the thread.  Without this gasket, the fuel does not have to rise to the top of the air horn to flow into the air corrector jets, but rather the seam between the bottom section of the fuel bowl and the air horn bowl cover.   The correct gasket does not have a third hole below the air corrector jets.  I believe Weber simply used the "3-hole" gasket on a couple of carb models to save costs, but this hole allows fuel to flow in the air corrector jet area on steep inclines.

This is the gasket that you do not want to use.  Notice the third hole to the left of the two air corrector jets.

This is the gasket that you want.  Notice that it seals off the bowl area.  The other gasket has a hole that overlaps the bowl and air corrector jet area.

 The bottom line to the mod is that the ONLY thing I did was fill the 1/4" by 3/4" rectangular vent hole that is on the top plate of the carb over the fuel bowl.  The drilling on the spare port the mod talks about didn't have to get done because there was already a 1/4 inch hole there and the brass fitting was there with a fuel vapor hose attached to it running to the charcoal canister.  I tried removing that vapor hose from the canister and just letting it dangle so there was nothing blocking the end of it so I knew it could breath.  That didn't make any difference in the way it ran.

The floats were set pretty low when I opened it up but the carburetor shop I took it to took those back to level while attempting to fix my problem so now they are raised back to factory level.  Either position exhibited the same cutting out at full throttle symptoms.  They also increased the size of the main jet and the idle jet both I believe.  I have to take it apart again and see what they left in there though.  The guy pretty much kicked me out of his shop when he got frustrated with not being able to fix it so I'm not sure what's in there now.

Jonny, I'm thinking you are right in your first assessment that maybe the bowl is not vented right now so the fuel can't fill it fast enough.  That vent 'slot' I filled with JB weld is loosely connected to the slot the air jets so I'm wondering if this carb was designed so as to suck any pressure buildup out of the bowl rather than just vent it out (if that makes any sense).  When I say 'loosely' connected I mean if you look at the surface of that top cover the wall that separates the fuel bowl from the opening into the air jets doesn't extend all the way to where the gasket would seal it.  Maybe that is what you are talking about when you were describing how the factory gaskets do not seal off the bowl vent-air correction jet area.

Capt, From what your have been describing this Weber must be close to the '2010' model you're talking about.  The 'drilled' vent looks factory, the floats are plastic and there is a vapor line running to the cannister.

Maybe the gasket is my problem.  It took me a while to figure out what you were talking about in the photos you posted (Kind of a 'Where's Waldo' puzzle)  but I think I understand.  I'll have to look at the gasket and see what I have. 

Except for the incline and rough road stalling problem it ran well before I did anything to it  so maybe I need to undo that and get it back to where it runs good again and re-think it.

Good, I guess I uploaded the photo correctly.  Note the hole and brass fitting described in the modification are already there.

If you expand the photo you'll see where I used the JB weld in the fuel bowl area.  That's the only thing I did.  The air jets are just on the other side of the thin chamber wall next to the vent I filled with JB weld.  That's where I was saying the fuel bowl is 'loosely' connected the chamber the air jets are in.  That thin chamber wall is not flush with the surface of the cover so the gasket will never seal the fuel bowl from the air jets. 

First, I want to say, this is a Weber Redline Carbs Kit I BOUGHT in 2010.
I have the carb all re-assembled and on the engine already, (on engine stand as I am finishing the 4 small rust out area repairs before paint)
The top you have pictured looks very close to what I have but the vent to charcoal canister
is a threaded 90 brass barb fitting.

The vent hole I'm referring to is the one in your pix above your J B welded area, above the restrictor jets, right in front of the choke plates.

And Johnny, I believe I have the 3 hole style gasket, but I could see easily the jets in the bottom of the float area thru this opening. I can still pull the air cleaner adaptor off to investigate, will try to get pix, small hole, the infa red range finder gets confussed on these up tight pix. But again, I running OK, "If it ain't broke, don't mess with it"

Running good again finally. Drilled out the JB. Jetted it back down to 130/140 primary/secondary. Thanks for the heads up on the gasket Jonny. I have the one with the third extra hole that doesn't seal between the bowl and the air compensation jets. I can see how on incline raw fuel could get through. All I have to do now is find the right one. Do you know where I can get it?  All of the ones I see online appear to be the wrong ones.

 If that doesn't solve my incline/rough road problem when the budget comes available maybe I should go for a my-Side. I read that they work pretty good. Anybody have any input on that or know where I can find a cheap used one that they no longer need? I sure as heck can't afford an engine swap. I'd be down for a year doing that anyway. Never done one before.

Have my 6.5 gears and stage two clutch in hand and headed out to the son-in-law's house tomorrow morning to put those in. He has the garage, tools and expertise. I'll keep up with the Rubicons at the Moab Easter Jeep Safari next month if it kills me!

Thanks for all the help guys!

All I have to do now is find the right one. Do you know where I can get it?  All of the ones I see online appear to be the wrong ones.

Ever thought of making one?  One of the things I learned to do as a teen was make gaskets, I can buy gasket paper here, but if it's not available, heavy paper or light card stock (for what you're looking at) - cut it roughly to size, locate the holes for studs and cut those with a sharp knife, and then use the carb itself and a small ballpeen hammer - put the card stock over the carb and tap around the edges with the hammer to cut it to exact size & shape.

You can probably find youtube videos on how it's done - the last one I made was for free wheel front hubs.