Topic: Weber carb set-up

[Tintop]

The shafts can/do wear Brian, usually because of excessive side load from heavy return springs acting on only one end.  As mentioned they can be changed.  Just make sure you reinstall the butterflies with their bevel in the right direction.  If your looking for the nth degree of air flow, you can file down the shaft (over & under butterfly only); and cut down the screws so they don't protrude. 

As for 14 degress - temp or angle??  Temp isn't an issue, angle is.  They shouldn't be more than 5 degress +/- from level.  Shouldn't be an issue with an SOHC because of the rubber boots.  You'll probably also want to support them so they don't sag, also because of the rubber boots.

[lwahples]

      After installing the Webers,it took awhile to get the bike to idle. Went
to 50F9's but the mixture screws are at 1 3/4 and the idle screw is turned
up. Still need to fine tune,but so far really like Webers!
                                                                                       Larry

Do you mean the idle speed screw is tightened up as far as it will go, or close to it? Those 50 idle jets are pretty big, especially with 1 3/4 turns out on the mixture screws. I'm guessing you've either got a vacuum leak, or very black spark-plugs.

I was told that I may have a vacuum leak, My Webers still have the leather seals which are prone to leak. Replaced them along with adding an O-rings to the mixture screws.
The idle screw is up just past the half turn that is talked about in the books I've read.The reason for 50F9's was due to the mixture screws being at the 1 3/4 out. And yes,the plugs should be black from how this is set up. But they are more of a tan. But I've yet to ride the bike,that will have to wait for the snow to go away.
                                                                                          Larry

[scottly]

I pulled the parts covering the throttle shaft bearing off today (for the first time, as I never had any reason to) and took some pics.

[scottly]

Larry, the first place I would look for a vacuum leak would be the rubbers where the manifold is joined to the intake spigots on the head, not the leather seals on the throttle shafts. Which manifold do you have? The first pages of this thread have some pics of most of them.
I'm still not understanding your setting of the 1/2 turn of the idle speed screw? I think you may have been led astray by the Haynes book chapter 5, section 8?

[scottly]

Just for grins, here is a pic of an adapter I built years ago to fit 2 DCOE 40s to the single plane 4-barrel manifold on the 413 CI V-8 in my VW bus. 

[Tintop]

Good picture of the shaft/butterflies scotty.  You can see how the square edge of the shaft, and protruding screws can disrupt the air flow.  Can't find a picture ...but the edges were tapered away with a file, and the screws shortened flush on the race 45's in the Cortina.  Note only a mod for the brave, very easy to end up with a bent, or broken shaft.  Mine were done by an x Lotus/Mclaren race mechanic.

Did that manifold work??  Looks like they would have been working against each other, unless there was a baffle in the middle.

[bear]

As for 14 degress - temp or angle??  Temp isn't an issue, angle is.  They shouldn't be more than 5 degress +/- from level.  Shouldn't be an issue with an SOHC because of the rubber boots.  You'll probably also want to support them so they don't sag, also because of the rubber boots.

Angle is my issue. I was hoping I could get away with running them on Johno's 14deg head.
I may be able to run the head but there is no way they will let me use flat slides.

Cheers,
Brian

[johno]

Re the operating angle, in an ideal world they say 5 degrees but back in the Scottly's VW van days we used to run them on everything that moved,  such as rally cars and  hill climb cars and as they were custom fit ended up at some weird angles.    I never had any problems that float levels or fuel pressure didnt fix.
I would be comfortable running at that angle, not sure about the impact on the G's your chair generates?   ............. if you have fuel surge problems just put a slower jocky on board       or fatter swinger

For a mate I am fitting up a cb sohc 1,000 cc engine into a lateish yamaha delta framed 750 at the moment for a drag bike and it has the 14 deg ports.   I'll take some pics on the weekend as I have to mock the engine with mikuni smoothbores to see if they fit in between the frame rails, I can put on the webbers for a look ?
cheers

[Tintop]

Agreed you can get away with more severe angles, but as mentioned you may have to play with pressure and/or float heights. 

Easier to just change the angle of the spigots on the manifold to compensate.  Lots of Weber manifolds on cars have curved runners.

[scottly]

Did that manifold work??  Looks like they would have been working against each other, unless there was a baffle in the middle.

It actually worked pretty well, up to about 4500 RPM. The major changes were to the accelerator pump; I ended up using the longest pump rods, stiffer springs, and partially blocked return jets to get enough squirt with the .35s. Idle jets were drilled (previously sacrificed; drilled, soldered, and re-drilled, same as the mains) to about .6-7, with mains about 1.70 or more; after a certain point, increasing jet size no longer had any effect. About this time I switched to a very crude home-made EFI.. 

[bear]

Re the operating angle, in an ideal world they say 5 degrees but back in the Scottly's VW van days we used to run them on everything that moved,  such as rally cars and  hill climb cars and as they were custom fit ended up at some weird angles.    I never had any problems that float levels or fuel pressure didnt fix.
I would be comfortable running at that angle, not sure about the impact on the G's your chair generates?   ............. if you have fuel surge problems just put a slower jocky on board       or fatter swinger

For a mate I am fitting up a cb sohc 1,000 cc engine into a lateish yamaha delta framed 750 at the moment for a drag bike and it has the 14 deg ports.   I'll take some pics on the weekend as I have to mock the engine with mikuni smoothbores to see if they fit in between the frame rails, I can put on the webbers for a look ?
cheers

Look forward to the pics mate.

Cheers,
Brian

[sohc boy]

 Ahhhh, Aussie inginuity alive n well in S.A.  , YAMONDA , like to see some pics of this Frankenstein myself....

[valt]

Out of curiosity what are you guys using for a throttle linkage?

[Tintop]

I use this bottom pull single cable set-up on the sidecar.  It's backed up by an external return spring.

http://www.piercemanifolds.com/product_p/pm40930.htm

[Tintop]

Posted this as part of the sidecar update, but thought I should also put it here as well.   After going through the carb it appears that the discharge was a '0' (no number).   With the large (50) pump jet this helps explain the A/F readings from the original dyno test.   So I've ordered additional Weber parts from Pierce Manifold in CA, and added a Syncometer to the list for the tool box.  Parts ordered:  Pump Jets - 35 & 40 / Discharge - 50 / Idle Jets - 50F9 / Air Correctors - 190.

Initial setup for the 'test & tune' day will be - 50F9 idles / 140 mains & 185 airs / F11 emulsion / 35 pump jet / 50 discharge.

The carb is a steel shaft, 'Bologna built' 40DCOE149 no.4M.   In addition to provisions for vaccum takeoff (brass plugs beside idle adjusters), this carb also has an air corrector (?) for the idle.   Hummm.....going to have to check out settings there.

[scottly]

By "no number", you mean the discharge is solid, no hole at all, correct? Have you measured the stroke of the pump yet?

[Tintop]

By "no number", you mean the discharge is solid, no hole at all, correct? Have you measured the stroke of the pump yet?

+1, no number / no hole for discharge.  Can't find it in my notes at the moment, but stroke is 10 (if memory serves )  New bits & pieces shipped today from Pierce Manifold (great service!), should have them mid next week.  Should be back together, and running before the 20th.  Opens the possibility of another dyno run, before 'test & tune' weekend.

[scottly]

The 50 pump jets, with a blanked-off discharge is a LOT of pump! I think you will be much closer with your new set-up.
My carbs don't have the extra brass plug, but there is a boss cast into the body there. What is underneath it? Is there an extra hole in the throat, between the cold-start opening and the idle/progression holes?

[Tintop]

The 50 pump jets, with a blanked-off discharge is a LOT of pump! I think you will be much closer with your new set-up.
My carbs don't have the extra brass plug, but there is a boss cast into the body there. What is underneath it? Is there an extra hole in the throat, between the cold-start opening and the idle/progression holes?

+1 , mega pump.   Also adding some serious enrichening to the mains.  The brass plug beside the idle screw covers a port to the back side of the butterfly.  It's 5mm, and were I screw in a brass pipe (that links to guages), to sync multiple carbs.

The other screw with lock nut (base of pump jet) has a tapered end.  The air channel (cast ridge) goes from the pump jet (off to one side), exits in line with idle opening.  They've been closed so far, will use them this time for final sync (after idles).  Looks like Weber's answer to drilling a hole in the butterfly.

[lwahples]

  Just an update on my setup. I made plugs for the progression hole that is closest to the airhorn. Which made it possible to run the mixture screws at 3/4 to7/8 out.I was also able to go back to 45F9 jet.
http://www.nooffswitch.net/lathe/lathework.jpg
   Tilting my carbs up helped also. It will now idle nice and rev up smooth.

[scottly]

The brass plug beside the idle screw covers a port to the back side of the butterfly.  It's 5mm, and were I screw in a brass pipe (that links to guages), to sync multiple carbs.

The other screw with lock nut (base of pump jet) has a tapered end.  The air channel (cast ridge) goes from the pump jet (off to one side), exits in line with idle opening.  They've been closed so far, will use them this time for final sync (after idles).  Looks like Weber's answer to drilling a hole in the butterfly.

I didn't even notice the screw with the lock nut! That's two differences between your carb and all 5 Webs I have! Unlike the boss for the sync port, there is no raised area for the air channel.
To the side of the jet cover, opposite the fuel inlet, my carbs have a bold W, with Italy in smaller letters. Was your carb made in Italy, or Spain?

[scottly]

  Just an update on my setup. I made plugs for the progression hole that is closest to the airhorn. Which made it possible to run the mixture screws at 3/4 to7/8 out.I was also able to go back to 45F9 jet.
http://www.nooffswitch.net/lathe/lathework.jpg
   Tilting my carbs up helped also. It will now idle nice and rev up smooth.

Now that you have the proper idle jets, along with the appropriate screw adjustments, you should remove the plugs!! The progression holes are not normally in use during idle; your incorrect settings were causing them to be involved. 

[Tintop]

I didn't even notice the screw with the lock nut! That's two differences between your carb and all 5 Webs I have! Unlike the boss for the sync port, there is no raised area for the air channel.
To the side of the jet cover, opposite the fuel inlet, my carbs have a bold W, with Italy in smaller letters. Was your carb made in Italy, or Spain?

Finally back on line...took a week for the provider to trace a line issue.

My carb was made in Italy, it's from either a Lambo, or Maserati V12.  There are other internal differences.  There are two balls in the pump demand well, one below the demand weight, and one above.  There is also a hole in the cover.  According to the guys @ Pierce this stops the pump jet from acting as a high speed enrichen circuit.  I can however convert it back to the original type, just remove the 2nd ball, and replace the covers with ones with no hole.  It also has the later idle screw which has a base setting of 2 1/2 turns out (which equals 1 with the old style).  So I'm probably going to be rich now with an 50F9.   They also suggested I go to a stiffer spring on the accel pump, but leave the stroke the same.

[scottly]

It also has the later idle screw which has a base setting of 2 1/2 turns out (which equals 1 with the old style).

What is the difference in the idle screw? Is it a very slight taper compared to the standard ones? Any idea what year Lambo or Maserati it was used on?

[Retro Rocket]

It also has the later idle screw which has a base setting of 2 1/2 turns out (which equals 1 with the old style).

Any idea what year Lambo or Maserati it was used on?

Probably a fast one Scott....