Weber 40 IDF / Dizzy question?

[Gütterßnipe]

Can I run twin Weber 40 IDF's on my Lovely electronic ignition vacuum Dizzy?
If so please advise what is required connect........

Or do I need to get hold of a 009 type?

Cheers

 

[jonboylaw]

There should be a vac port near the base of one of the carbs, just look at the butterflies as you need a ported vac signal for the dizzy.


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[Todster]

Hi,
I'm just fitting EMPI HPMXs to mine, (basically copy of the Weber IDF) and they have a port each for Vacuum. (I thought I was going to have to get a couple of connectors to thread into the ports, but they are the port that sticks out with a cap in the end, just unscrew the cap, and slip the vac tube on) Although, the vac port only seems to be drilled into one of the throttle venturis on each carb. I'm running the 123 dizzy with vacuum and don't want to go to the expense of changing for the non vac one, so, I'm going to give it a try on only one of the vac ports, and if it doesn't have enough, i'll tee the two together and see what that does.

I've been researching this a lot just lately, and there seems to be lots of contradictory info out there, with some people drilling their manifolds to tap from. (I've even seen someone take a drill to the carbs and put 4 vac ports in) I personally don't want to go down that route, and, from what I've read, the vac should be taken from just below the throttle butterfly anyway, which is where the port is on the IDFs.

As soon as I get my engine run in, the first place it will be is on the rolling road to tune the carbs up. (put a new cam in, so the first 30 minutes will be spent 2000 - 3000 rpm to bed the lifters in)

Hopefully, it will be done in a couple of weeks, so will update once I have a working solution.

Cheers
Mark

 

[jonboylaw]

For a standard type dizzy, the vac signal is a "ported type" meaning the it has the vac take off in line with the closed butterfly. I am trying to remember here but I think it gives a low initial vac that jumps high just as you open the throttle then drops off as the throttle widens. The low closed throttle signal allows the dizzy to be well retarded for emissions I think, then gives it a good load of advance as you initially accelerate to get you going, then falls off for WOT as the mixture richness up and has a longer burn (less advance needed).
I use manifold take off on the megajolt as it does not require the low initial vac signal. Other dizzy's may also be the same. The ported vac signal is definitely what the original dizzy requires.


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[Todster]

I took a couple of photos of the port on one of my carbs tonight.





Cheers
Mark

 

[Gütterßnipe]

Cheers Mark

So is this the Vacuum tube??

Spence

 

[Gütterßnipe]

I took a couple of photos of the port on one of my carbs tonight.





Cheers
Mark

Cheers Mark

So is this the Vacuum tube??

Spence

 

[Todster]

Hi Spence,
From all the documentation I can find, that port that I connected my vac tube to is shown as the Vac Port, hopefully I'm going to have it back in and running in the next couple of weeks, and we will see how effective it is when I get it to the rolling road.

Cheers
Mark