does anybody know how to get a vacuum signal out of a Kadron carb so I can use a vacuum advance distributor??

My engine is basically stock 1916 with an Engle 110 cam and twin Kads. I am looking at taking all of the driveability and tune issues out of it and this is one thing I am looking at.

regards

Old Hutcho

here is a pic, I 'borrowed' it off the web somewhere, so the credit goes to 'unknown'..
Remove the throttle body from the carb, and drill out the aluminium plug.
If you follow the hole it comes out just above the throttle plate. I used an old vac takeoff tube from an old carby, it was a perfect fit. That port is tight against the stock fan housing on the left side carby, so you might consider doing it on the right hand carby.

Uber Kafer

Brilliant. Thanks for that. Have you noticed any improvement using a vacuum advance distributor after you did that mod?

regards

Old Hutcho

you also need to plug this hole in the throttle body

I havent fired it up yet, just did it 2 weeks ago and sorting out other issues first. However, that approach is the way to go, just a few variations are available on the net.
t2.... whats the theory behind plugging that hole? I've seen it reccommended on some sites, but not on others. From what I can see it sits below the throttle plate when fully closed, but once off idle its all in the same flow... so whats the story there?

I am also learning this process and from what i have read on it so far this is why.
That port needs to be blocked so it creates the proper vacuum signal for the distributor, the vacuum port also should not give any vacuum signal at idle as the engine does not need the distributors advance or assistance at idle.

and that makes sense.

thanks.

If you have vacuum at idle you will have manifold vacuum.
If the vacuum enters below the throttle plate ,it then becomes manifold vacuum. Manifold vacuum gives you more advance at idle.
i have been informed that as a rule of thumb vacuum advance distributors almost always use ported vacuum.
SVDA distributors need ported vacuum, that is the port above the throttle plate. the vacuum only comes on when the throttle plate is opened.
The vacuum port you drilled into the carb body will pull the vacuum through a venturi controlling the amount of manifold vacuum to the distributor once the throttle plate opens.

Do you have the balance tube fitted between the two manifolds ?

i havent got that far yet, some people say yes 100%, others say no way.
i am going to try it both with it and without just to see the difference

You MUST run the balance tube between the manifolds..........non negotiable !

there you go i will put one on then