Bosch distributor in 128 question

W

Watry

Daily Driver
My 128 wagon has a 1500 from an X1/9 with carb and the X's Bosch electronic distributor. Distributor has built-in mechanical advance, seems to work well. The dist also has a vacuum chamber, but the vacuum line to the carb was blocked off when I got it. My question: does the vacuum need to be hooked up to get full advance out of this unit? Someone has suggested the vacuum is a retard mechanism for idle timing, rather than an advance.

When I hooked up the vacuum line, it ran very stumbly, as if the chamber was perforated.

I could put the unit on a dist machine and see how much total advance, but thought I'd ask first here if anyone knows. Thank you.

Andrew
 
dizzy

I have a Bosch electronic dizzy on the 1500 X motor in my 128 with no vacuum hose hooked up and the car runs just fine.
 
Thanks. Mine runs fine too, I just wonder if I'm getting as much advance as it was designed to have. The marks on the pulley go only to 10 BTDC, and full advance is way beyond that, but there's no max mark that I see, which I'm used to no Alfas.

Andrew
 
timing

Get a dial back type timing light. It is adjustable so you can use the 0-degree mark on the motor and just turn the knob on the timing light to reset to the timing mark at any rpm. I think mine goes to about 60 degrees. Vacuum advance should have no effect on maximum timing as it does not come into play at full throttle.

carl
 
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