[BigOrange90YJ]

Yes, yes I know I'm a YJ guy but a 258 is a 258.

I've been reading and trying to completely understand adjusting the weber using this write up Weber Carb Tunibg

One thing I am confused about is in step 1. he says to "..Gently bottom mixture adjusting screw (the one at the base) and back out 1.25-1.5 turns..."
in step 5. he also says the "...idle mixture screw..." is "...(the one at the base)..."
So, what I am confused about is the 'screw' in step 1. the same screw as in step 5.?

Update:

Originally Posted by BigOrange90YJ

Here's where I am at:
Current screw settings

1. Idle mix screw - 2.5 turns out
2. Idle speed screw - 1.5 turns in
3. Timing - 12* BTDC

I fixed the screw tightening problem by getting slightly longer screws of the exact same thread

I still cannot idle with the above settings. Could not find any vac leaks on the carb itself. (around the gaskets) Well actually its idling for quite a while with these settings surprisingly at what looks like on the rpm gauge is 10rpm.

[alex211]

It's the same screw.

[BigOrange90YJ]

Is there also a 'mixture screw?' I'm having trouble identifying where all the adjustments screws are located.

[alex211]

There is either one or two screws that adjust the idle mixture. I don't know how many for sure (I have never worked with a weber), but usually there is one for each venturi.

[swatson454]

There is an idle speed screw on the firewall side of the carb where the linkage is and a mixture screw on the side. This is a pic of my 38. Yours may not look exactly like this but it'll be close. It may be on the other side of the carb but it will look like this. The mixure screw is the spring-loaded screw just below the gold anodized linkage bracket.



Hope it helps,

Shawn

[BigOrange90YJ]

the best picture i found before your picture is in this illustration
where it appears the idle mixture screw is on the engine block side

[swatson454]

Originally Posted by BigOrange90YJ

the best picture i found before your picture is in this illustration where it appears the idle mixture screw is on the engine block side

Yep. Mine is synchronous and that made a much easier pic

[BigOrange90YJ]

ok i'm (the noob) stumped...

I can't even get my throttle screw (idle speed screw) to get close to the throttle linkage


also, could someone please explain in detail what exactly what 'bottom mixture adjusting screw' means how do you know when its at bottom? i screw and screw but i dont want to screw anymore 'cause i feel like im going to break the spring. When I turn this screw in every and both which way direction, all the way in and all the way out, while the engine is running i hardly get any change in RPMS



sorry for bad quality camera phone pics

[swatson454]

Ok, it's time to make sure that the choke is pulling off correctly before we go much further. From you're pic, which was very helpful btw, it appears to be hanging up on the fast idle cam.

When the engine is warm, is the choke plate (the butterflies at the very top of the carb when viewed with the air filter off) vertical?

Shawn

[BigOrange90YJ]

how do i bottom a mixture screw? i feel like i cant screw it in too much cause ill break the spring or the screw

[mcmud]

Big 'O', There should be plenty of mix screw travel to the seat prior to the full compression of the spring. As it reaches the bottom (seated) you will feel it.

I notice the gap shown between the speed screw and the (cam)Lever. If your engine is warm the choke plate should be fully opened and that linkage arm allows the lever to return to the default position. The Lever (the part that the screw contacts) will be in position for more than enough speed screw length prior to that full spring compression.

If the Lever is not able to draw near the point of the screw while it is fully withdrawn then either the C.plate is closed or there is linkage binding.

The nut which holds the throttle linkage to the Primary Throttle Rod should be finger tight and then turn one flat, then bend the tab of the lock washer to hold the nut.

Always.. before adjusting a carb fully warm the engine. If the choke is out of adjustment then warm the engine and insert something between the air horn and the choke plate to maintain it in the full open position. I use a short piece of 3/8" id tubing inserted vertically between the plate and the wall.

[BigOrange90YJ]

i cant get the idle to get above 1000 rpms without using the speed screw(even the speed screw all the way tight hardly gets me above 1000 rpms), only other thing that did it was advance the timing a ton, about 40* was a good smooth engine.. that didnt seem right, its supposed to be around 8*, correct?

also, i got the speed screw to touch the throttle linkage, i just had to wait for the engine to warm up and the choke to come all the way off

[BigOrange90YJ]

So here's where i'm at, all im worried bout is idleing correctly right now. Idle speed screw is 3 turns in once touching the linkage. and the ile mix screw.. is 5 turns out. yes i understand that the correct idle speed screw setting should be about .5 turns and the idle mix should be from .5 to 2.5 (or more preferably 1.5) turns from bottom. My timing is set to 8* and I am getting quite a bit of vac out of the S port (vac advance port). The settings above are what I have had to do to keep it idling.. for now, and it runs terrible...

I also cannot get the carb to mount all the way to the manifold on the engine block side. When the engine is running vac pressure seems to hold it down but im sure im losing vac in it somehow.

Please... what do I do first.


I have been using the following links as reference:
Adjusting a Weber
Weber Works
http://www.jeepforum.com/forum/f12/weber-rebuilt-wont-stay-stay-running-964621/
http://www.jeepforum.com/forum/f8/carb-help-972360/

and the main one I have been using:
Weber Carb Tunibg

Thank you for all your help.

[mcmud]

Originally Posted by BigOrange90YJ

i cant get the idle to get above 1000 rpms without using the speed screw(even the speed screw all the way tight hardly gets me above 1000 rpms), only other thing that did it was advance the timing a ton, about 40* was a good smooth engine.. that didnt seem right, its supposed to be around 8*, correct?

I'm not sure why you would want an idle speed in excess of 700 rpm. Turning the speed screw in more than 1.5 turns will cause timing advance if your using the "S" port and make the tuning of the carb impossible. I may need to point out that that setting is the maximum but the goal is to have the plate set closed so that no vacuum appears at the "S" port.

The initial timing should be in the neighborhood of 8* Some like it less and some like it set higher. In fact Redline Weber recommends 12* but without any vacuum advance. It seems to me that sometime back you installed the pre computer distributor. Is that correct?

Originally Posted by BigOrange90YJ

The settings above are what I have had to do to keep it idling.. for now, and it runs terrible...

I also cannot get the carb to mount all the way to the manifold on the engine block side. When the engine is running vac pressure seems to hold it down but im sure im losing vac in it somehow. .

Correcting the leak would be first on the list. It sounds a if you will need to remove and remount it. New gaskets may be required. Thread locking compound must be used on the hex bolts into the manifold, I recommend blue for that application.

Red locktite for the mounting studs into the second plate. Run the studs in until they are just a tiny bit shy of reaching the lower surface and allow it to throughly dry before proceeding with mounting the carb and at the install use a lockwasher on each stud.

Most likely during your tightening of the carb these studs actually pried the plates apart.

Oil or grease the gaskets well before use. Replace them if necessary.

The adapter plates are most time in need of a bit of milling. I recommend you lay a piece of course wet sand paper or even a sanding belt cut on a flat surface and add oil... keep the plates flat and remove any lumps.

Once the mounting is complete use the Guidelines provided by Redline, read them throughly and follow each of the steps in them.

[BigOrange90YJ]

It seems to me that sometime back you installed the pre computer distributor. Is that correct?

No, still using the factory dist.

I'm not sure why you would want an idle speed in excess of 700 rpm. Turning the speed screw in more than 1.5 turns will cause timing advance if your using the "S" port and make the tuning of the carb impossible. I may need to point out that that setting is the maximum but the goal is to have the plate set closed so that no vacuum appears at the "S" port.

I only mentioned i couldnt get it any higher because the guides i am using tell me to back out the idel speed screw to lower the rpms at 1000 rpms, well i cant even get it to start as a high idle so that I may be able to back out the screw.

Also, while tuning the carb I had the "S" port plugged. Fearing the vac to mess with my tuning.

Correcting the leak would be first on the list. It sounds a if you will need to remove and remount it. New gaskets may be required. Thread locking compound must be used on the hex bolts into the manifold, I recommend blue for that application.

Red locktite for the mounting studs into the second plate. Run the studs in until they are just a tiny bit shy of reaching the lower surface and allow it to throughly dry before proceeding with mounting the carb and at the install use a lockwasher on each stud.

Most likely during your tightening of the carb these studs actually pried the plates apart.

Oil or grease the gaskets well before use. Replace them if necessary.

The adapter plates are most time in need of a bit of milling. I recommend you lay a piece of course wet sand paper or even a sanding belt cut on a flat surface and add oil... keep the plates flat and remove any lumps.

Once the mounting is complete use the Guidelines provided by Redline, read them throughly and follow each of the steps in them.

definitely going to try and nock this out next, thanks

Originally Posted by BigOrange90YJ

So here's where i'm at, all im worried bout is idleing correctly right now. Idle speed screw is 3 turns in once touching the linkage. and the ile mix screw.. is 5 turns out. yes i understand that the correct idle speed screw setting should be about .5 turns and the idle mix should be from .5 to 2.5 (or more preferably 1.5) turns from bottom. My timing is set to 8* and I am getting quite a bit of vac out of the S port (vac advance port). The settings above are what I have had to do to keep it idling.. for now, and it idles terrible...

I also cannot get the carb to mount all the way to the manifold on the engine block side. When the engine is running vac pressure seems to hold it down but im sure im losing vac in it somehow.

Drive ability of the Jeep seems pretty good but I know when all this is done it will be amazing. What reasons would cause needing the idle speed screw so far in? and the idle mixture screw so far out?