I have a pair of Weber 40 IDF's. I plan updating them with the CB Performance kit. While I have them out, I would like to drill them for a vacuum advance distributor. I understand that the newer carbs already have the port drilled. Does anyone have a picture of one so I know where to drill the hole. I know it should be above the throttle plates somewhere.
Thanks,
Dean
Vacuum advance holes have to be very precisely drilled in order to get the right vacuum vs engine load curve. You'd have to be either very good, or very lucky to get it right. Once you have the hole drilled you have to pick the vac adv can that gives you the advance you want for the vacuum it gets. Do you know which can you want/need? There are dozens of choices.
------------------------------------------------ Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA
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Hey Jim,
Actually I lucked out, my 40 idf's are already drilled so all I need to do is remove the plug. I am going to use the svda distributer from aircooled.net.
That IS lucky. Do you have any idea if this port gives a vacuum signal that is appropriate for the distributor in question? John might know, but it's really NOT a trivial question.
------------------------------------------------ Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA
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I have confidence in John and the parts he sells. If he says it will work, it probably will.
Not sure that this conclusion is supportable. Have you looked at the advance curves in your Bentley manual and compared them with what you are thinking about getting? I find that the late distributors that have both vacuum and mechanical advance give the best combination of results, both power and economy, but the nature of the vacuum response these need would probably not match up at all with your Webers.
In most cases the second best choice is a good mechanical advance distributor, or the combo type, with the vacuum can left disconnected.
It sounds like you're coming from a viewpoint of someone who already has a mechanical advance distributor and is looking at all "that green grass on the other side of the fence." You might want to post what you have now for John to comment on. It might be a really poor example, or it might be a good one which happens to have a frozen advance mechanism (fixable!), or it might be better than what you were thinking of replacing it with.
------------------------------------------------ Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA
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Yep, I currently am running a plain jane 009 backed by a pertronix/msd6 combination. It was good enough when I was using a FI/Turbo setup but I did not do much highway driving with that setup. Now that I have gone back to the basics, the 009 just does not meet my requirements for touring. I encounter a similar problem with my other ghia after I added an AC unit. With a 009, it would overheat with the AC on while on the highway but would be perfectly fine in stop and go traffic. After tossing the 009 for a centrifugal/vacuum unit, the motor rarely overheated and never on the highway.
My engine bears no resemblance to anything VW produced so I am not sure what use I would get out of looking at a stock distributor curve. I am running a
2.1l type 1 that with a somewhat mild C-35 cam and reworked heads. All of this is trying to breath though some 28 mm venturi 40 idf's although I will be swapping these out for a 32 mm venturi. I have set the 009 for a maximum advance of 33 degrees. This is fine for acceleration but is a poor compromise at highway cruise. The distributor from aircooled.net does have both vacuum and centrifugal advance. Obviously the best setup would be a programmable ECU but for a 90-100 hp motor, it is not worth it to me. I appeciate your concern but I am confidant that the results will be positive. I have the distributor and if it does not rain this weekend, I will install it and give it a whirl. I'll post my results in a week or so after I get some driving time in.
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