not a single idle adjustment for dual webers?

thehackmechanic

thehackmechanic

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I'm trying to get this '73 running right. The timing was WAAAY off, and now that I think I've set it right, the idle is WAAAY low. It's been so long since I had a carburetted E9 that I forget. With the dual Zeniths, there's a single adjustment screw that sets the stop for the linkage for both carbs, but there is no such single screw on a Weber setup, correct? I need to set them individually, correct?
 
Not clear if you are referring to "rotary stop adjustment" (see Fig 2.12 below), but setup I have limited familiarity with was same as factory. Haven't worked on Weber conversions in a while, but obviously, some linkages may be different. Maybe this will help:


c_115b.jpg
00004004_z.jpg

autobooks_manual_037.jpg
c_115.jpg
 
I think there is a single adjustment screw on the linkage to synchronize the carbs but I am pretty sure the idle adjustment screws are on each carburetor for both Zenith and Weber. There is an adjustable stop on the linkage that is used to increase the rpm while adjusting ignition timing but that should not be used to adjust idle rpm.
 
I think that answers my question. The "rotary shaft adjustment screw" shown above is, I think, only present on the original Zenith linkage but not on the aftermarket Weber linkage. You're saying even if it were there it should only be used for timing, not for normal idle adjustment. Got it. Thanks.
 
Correct, and to dial in proper idle, you'll need vacuum gauge(s), air meter(s), or a hose to listen to the carbs with in order to sync them.

thehackmechanic said:
I think that answers my question. The "rotary shaft adjustment screw" shown above is, I think, only present on the original Zenith linkage but not on the aftermarket Weber linkage. You're saying even if it were there it should only be used for timing, not for normal idle adjustment. Got it. Thanks.
Click to expand...
 
Having just done a Zenith yesterday...

Are you using a vacuum retard side to your distributor?
Do you still have the smog stuff hooked up?
If no smog stuff is left you don't need retard and your idle will jump up.

Did you hand crank your engine to see TDC at the dampener and at the bellhousing?
Mark that spot with some silver paint and move 7 more teeth to the right and mark that spot too.
Different years use different marks, ballbearings and pins [short and long] letters [Z} and lines and 5 speed conversions screw things up even more. I verify and mark every flywheel for good reasons.
7 teeth after TDC is where you need to be at 1800 rpm on a cs with the vacuum line plugged and disconnected. [360 degrees divided by 116 teeth = 3.1 teeth]
[22 degrees divided by 3.1 = 7]
 
This is de-smogged car. When I first looked at the distributor, NEITHER the advance nor the retard side were hooked up. I ran a vacuum line from the advance side to the port just above the base of one of the Webers. I located the T|O line on the damper and marked it and the reference mark on the front cover with White-Out. I also found the TDC mark and the ball in the flywheel and marked them. Good tip about counting teeth -- didn't know that one. This was originally a carburetted car, so you're right about not knowing the true provenance of the marks. I did a quick timing using my advance timing light, setting the total advance to 36 degrees. I'll recheck it tomorrow using an RPM gauge. Thanks.
 
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