accelerator pump adjustment

[carrooth]

I've rebuilt my weber 40 ida's and set the float level. Next, i used the handy pharmaceutical quality vile to measure the squirt from the accelerator pump. The right carb (4,5,6) is squirting about .5 cc + or - .1 and the left carb (1,2,3) is .7 + .05 - .1. So the right side is squirting more gas than the left.

Now I'm stumped. how do i adjust the volume??? I've read about a nut but mine does not have a nut between the throttle linkage and the accelerator pump lever/arm. My connection is solid with a cotter pin holding it on to the part on the throttle linkage and another cotter pin holding it to accelerator pump linkage.

Obviously, with the volume off .2 per throat between carbs I would think this needs to be adjusted.

Help, please?

Jay

[Grady Clay]

Jay,

Originally the Weber accelerator pumps were not adjustable (#42 & #43).
I think this was only on early 40IDA3C and 40IDA3C1.



© 1965 Dr. ing. h.c. F. Porsche K.G.




Starting with the 40IDAP3C, 40IDAP3C1, 40IDT3C and 40IDT3C1, the accelerator pumps were adjustable (#42).


© 1965 Dr. ing. h.c. F. Porsche K.G.








There are two parts needed to update.
901.100.911.00 “Adjustable linkage left”.

© 1965 Dr. ing. h.c. F. Porsche K.G.

and

901.100.912.00 “Adjustable linkage right”.

© 1965 Dr. ing. h.c. F. Porsche K.G.


In the late ‘60s and early ‘70s, we replaced all of the fixed linkage with the
adjustable parts. It will probably be a challenge to find new spares now.

These are adjustable by loosening the lock nut (6 mm wrench size) and
changing the length of the rod with the other nut. This changes the starting
length and consequently the quantity of fuel squirted by the accelerator pump.

Best,
Grady

[carrooth]

Thanks Grady. That's exactly what I have. So, when you said "find new spares" I assume you were speaking of the updated linkage.

Nothing is easy, but that's also part of the fun I suppose.

Thanks again

[Grady Clay]

Jay,

After sleeping on this, I seem to remember there were more than one choice for
the adjustable linkage. I looked at later parts manual and didn't see them.

The difference was the shape (angle of red lines below) of the ‘ramp’ the pump
lever follows. This changed the accelerator pump fuel quantity for the same
stroke (movement of throttle).





Best,
Grady

[kens_74_911s]

have a set of 40 IDAs choked to 34mm on my 2.7 and running some early 02 cams where can I find these parts,looks like some early stuf/ I may need the s extra enrichment tubes but only looked at that a while back

[Mervo]

I have the adjustable type with the nut, spring and lever. (40 IDA) However my squirt volume is almost 2.0ccs with two strokes. With one complete stroke I get 0.75cc. Used the 'calibrated' (with a syringe) bent straw (356) approach. Does that sound in the ball park? Some say 2 strokes and others say 1?

[1QuickS]

One stroke for Webers & .7 to .9 cc per stroke.

Two strokes was used to check the Solex 40PI carbs used on the early (pre-Weber) SWB 911s.

[Mervo]

Cheers Paul. Reading back through these from years ago, makes me realise how amazing Grady Clay was and also how generous also.