123 Dizzy - with or without vacuum advance?, Sucks... Options

[chmillman]

Last post of the evening, promised...

Last year one of my mechanics suggested putting in a 123 dizzy. I said OK, why not. The model he installed was the dip-switch one with curve #2 set, but without vacuum advance port (plus a coil to match). The vacuum hose was simply plugged. Installing the 123 did not actually fix the hesitation problems we were having, which were most likely elsewhere in the FI system.

My other mechanic here who is a specialist in D-Jetronic stuff looked at that and said "This is not good, it needs at least vacuum advance!" He cleaned, lubed and re-set up the original distributor plus the coil and re-hooked up both the vacuum advance and retard hose connections. He's admittedly more of an 'originalist', says the whole thing is a system designed to work together, so he was not fond of replacing the original mechanical dizzy with an electronic one, especially without a vacuum advance. He pointed out that if one really wants to do that anyway, the 123 units were also available with a vacuum port, and suggested that the other guy simply ordered the wrong dizzy model.

So now I'm here in between these two guys - who are both my friends by now given the stuff we've done together - and I'm no expert in the matter, so I don't know who's 'right'... Possibly both.

[emerygt350]

I agree with wonkipop. You really don't need it if you are just bombing around having fun. If you do a lot of cruising then maybe it's worth worrying about. The real reason you want the 123 on there is the trigger points for the injectors. NLA and prone to failure after 50 years. And you don't need to mess with points. I had to use my old dizzy during the vintage grand prix and it was absolutely fine and not a ton worse than my 123... Until 5500 rpm. Then it fell on its face. With my 123 it revs up past 6k with flinching.

I have the pot style like yours, no Bluetooth. It does have the vacuum port and I do use it, but I have plugged it and driven quite a bit without it. No noticeable difference and I have all the gauges. I leave it on just because it's supposed to be better at cruise, not that I notice too much difference in heat, I think I do see a difference in vacuum level at cruise and therefore their should be a mpg bump. I also have mine set on 1.