Weber 40DCN question

[Fritter]

I have my Deano 40DCN carb kit installed on the engine in my '64 and running.  It idles great but stumbles when given the gas.  I looked down the throats and I see that gas does not come out of the accelerator pump jets when the throttle is activated, the gas dribbles out from behind the jets.  I now see that the problem is the "pump demand valves" that hold down the accelerator pump jets.  The fuel just dribbles out the hole in the top of this valve when the throttle is activated. 

Now, when I rebuilt these carbs, one of these valves was hollow and the other had a solder plug that I removed. 

I assume these valves are supposed to have some kind of ball/spring mechanism in them?  I've looked around the internet and I see I can buy new ones from Pierce, but the picture just looks like what I have, I can't see the inner workings.

I'm going to call Pierce about this, but in the meantime, does anyone have an insight on these valves?  Kind of obscure, I know!

Thanks!!

[nicolas]

hello,

i think these work with the ball system and they should move both freely. the one in the pump to suck in the fuel from the bowl and block off when you accelerate. this one may be overlooked sometimes, but is quite easy to check with the top of the carb off. and then there is the one in the shaft that indeed blocks when the pump is filled and then opens when you accelerate. the balls are indeed easily lost but usually just drop in and the pump jet is just screwed in over it. just be sure they both work freely.

[Fritter]

I don't believe there are any loose balls in a 40DCN.  Hey, that sounds funny. 

[nicolas]

I don't believe there are any loose balls in a 40DCN.  Hey, that sounds funny. 

it does sound funny, but i could be wrong indeed as i can only compare to DCNFs... maybe mail monkiboy as he had some on is buggy

[Lee.C]

No there are no "glass balls" in a DCN - its a pretty direct passage/galley from the accelerator pump to the jet/nozzel/outlet - just like a basic solex carb - My advice would be to strip the carb inc the accelerator pump and shot some carb cleaner/brake cleaner/high pressure air down the hole in the accelerator pump housing - I hope you get what I mean 

Here is a little more on my old DCN's - You may notice I kind like them   

http://cal-look.no/lounge/index.php/topic,6900.0.html

[Fritter]

Got new pump demand valves from Pierce and the carbs now run great!

[OC1967vw]

I have my Deano 40DCN carb kit installed on the engine in my '64 and running.  It idles great but stumbles when given the gas.  I looked down the throats and I see that gas does not come out of the accelerator pump jets when the throttle is activated, the gas dribbles out from behind the jets.  I now see that the problem is the "pump demand valves" that hold down the accelerator pump jets.  The fuel just dribbles out the hole in the top of this valve when the throttle is activated. 

Now, when I rebuilt these carbs, one of these valves was hollow and the other had a solder plug that I removed. 

I assume these valves are supposed to have some kind of ball/spring mechanism in them?  I've looked around the internet and I see I can buy new ones from Pierce, but the picture just looks like what I have, I can't see the inner workings.

I'm going to call Pierce about this, but in the meantime, does anyone have an insight on these valves?  Kind of obscure, I know!
 
Thanks!!

both BERG and Pierce provide great tech service.....