Giving Up On Vacuum Advance Options

[Ansbacher]

Car = '74 2.0 Liter, Dual Dellorto Carbs

For years I have been 'adequately" running an 009 mechanical only distributor. Finally took the pervasive advice out there to go with a vacuum advance dizzy from a 1.8L 914. Since only one of my Dellorto carbs had an existing vacuum port (ported type), I had to drill a port in my other one (no problem there). I used good quality anti-pulse valves in the lines and measured a maximum vacuum of 12 inches of mercury with partial throttle.

Installed the 1.8 dizzy and set the timing, first without the vacuum lines attached. To satisfy my usual 30-32 degrees at 3500 RPM, the idle timing had to be at about 5-6 degrees (quite low for my setup which is happier at about 10 degrees. When I attached the vacuum lines my timing at 3500 RPM went sky high into the 40s. This seems way too high. Is this normal? Overall, I found the car to run better without the vacuum attached and the carbs plugged off.

Am I doing something wrong here? I don't like the numbers I am getting. Everyone said this was the way to go with carbs, but I am not seeing results. Advice appreciated.

Ansbacher

[Tbrown4x4]

I'll be watching this with interest. I'm going through a core 205 AA distributor right now. I wasn't planning on using the vacuum advance though. (1.7 with 40 IDA's)

If the total advance at 3500 rpm is really over 40, maybe you can install some kind of limiters to prevent the centrifugal from rotating the points plate that far. I agree about the vacuum advance not affecting total timing. I believe at 3500 rpm, the weights should be against their stops.

I also have an 009 in my car (installed by PO) that works OK, but was curious about other timing curves. I mean, can a distributor designed for a stationary engine really work well in a car?

Also, looking at a chart comparing 914 advance curves, I think the 1.8 just has a steeper curve that is shifted to a higher RPM range. Meaning it starts advancing later and is still advancing at a higher RPM.

Your timing numbers make sense because total advance = base timing + mechanical (at 3500 RPM).

I can put the stock 1.7 dizzy in, but the centrifugal can start as low as 700 RPM, and my idle speed is above that right now. I never worried about base timing because I just set the total at 3400 RPM and called it good. When I checked, the base timing was only 1 or 2 degrees. You should have smelled the exhaust!

Really eager to hear more opinions on this. A 123 Dist sound awesome, but certainly not in my budget.