Vacuum advance retro-fit

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maytag
Posts: 1789
Joined: Mon Oct 19, 2009 9:22 pm
Your car is a: 1976 124 spider
Location: Rocky Mountains....UTAH! (Not Colorado)

Vacuum advance retro-fit

Post by maytag »

Mornin' all!

So, I've installed an electronic ignition distributor from my '80 parts car into my '76. It was too late last night by the time I got the new vacuum advance diaphragm unit on the dizzy for me to go poking around much. So a really quick question here:

For those who've done the same (or who know anyway):
Where have y'all pulled vacuum from for the advance unit?

And once I'm all set, how much advance will it give me? Any idea what the curve looks like at WOT? Or? (stock 1800) I'm trying to decide what to start at with my initial timing, so any suggestions that way would be appreciated too. Don't wanna have to re-invent the wheel, I know many of y'all are much smarter 'n me, and have been down this road as well.

Thanks in ADVANCE (tee-hee-hee..... pun intended)
:lol:
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
BEEK
Posts: 1833
Joined: Wed Mar 24, 2010 10:45 pm
Your car is a: 1975 Spider
Location: clermont fl

Re: Vacuum advance retro-fit

Post by BEEK »

find a port on the carburator that does not have vacuum at idle, when the throttle is opened then the port has vacuum.
meaning the vacuum is pulled from above the throttle plate.
Automotive Service Technology Instructor (34 year Fiat mechanic)
75 spider
, 6 Lancia Scorpions, 2018 Abarth Spider, 500X wifes, 500L 3 82 Zagatos. 82 spider 34k original miles, 83 pininfarina, 8 fiat spider parts cars
son has 78 spider
majicwrench

Re: Vacuum advance retro-fit

Post by majicwrench »

I would try a off-idle port as suggested, but also try a regular full-vacuum port. Some engines like the ported vacuum, some like manifold vacuum, experiment. A little looking should let you know how the '80 was arranged, so that would be a good clue too. I would set timing however the '80 had it, and then perhaps experiment a few degrees from there.
At WOT the vacuum advance does nothing and will not affect the total or the curve.
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