Vac Advance Distributor Upgrade

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Mon Dec 04, 2006 2:05 pm

A few months ago, I upgraded the dual-points distributor on my '78 Spider for a vac advance electronic ignition from an '80 spider.

While looking at the vac diagram for the '79, I noticed that there is a "vacuum delay" valve in the vacuum line that runs from the advance unit to the intake manifold. There are vac lines also from that valve to a thermovalve in the manifold.

What does that valve do? When should the distributor get vacuum? Mine's been getting vacuum all the time. My car seems to run fine, but also seems like it should be faster than it is.

-Ted

So Cal Mark · Post by **So Cal Mark** » Mon Dec 04, 2006 2:11 pm

all of those vacuum valves on the 79 were to allow the engine to meet emission standards. The 78 should just have a hose from ported vacuum on the carb to the advance unit.

Vac adv won't make your car faster, it's primarily for mileage since it works at high vacuum situations (cruise, light throttle)

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Mon Dec 04, 2006 2:18 pm

I don't think mine's ported. I think it's getting full vac all the time.

So Cal Mark · Post by **So Cal Mark** » Mon Dec 04, 2006 3:13 pm

all that will do is advance the timing at idle

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Wed Dec 13, 2006 6:54 pm

I disconnected it, and it seems more powerful at low rpms. Where would one find ported vacuum on a '78 emission system? Is there any?

So Cal Mark · Post by **So Cal Mark** » Wed Dec 13, 2006 9:18 pm

it has to come from the carb, above the throttle plate