Vacuum Advance?

[johnssi]

Hi All, I've got the trans out of my 81 spider and in looking around underneath I noticed the the far end of the tube coming from the vacuum advance on the distributor is not hooked up to anything. Is it supposed to be? Any advice would be appreciated.

[rlux4]

It whould go over to the intake plenum, there is a nipple directly under the throttle spring. It's tight quarters, so you'll need a pair of needle nose pliers to slip it on.
Ron

[johnssi]

Thanks Ron. What kind of symptoms would show from it being disconnected?

[ari]

I had no adverse side effects. It will improve gas mileage slightly.

[rlux4]

I replaced mine shortly after I got my car and the new one blew the diaphragm out in just a couple of months. I've run without it since then (plugged the line) and can't tell any difference. Even passes California's smog test fine. Other very experienced Spider owners have driven my car and they also said it had good performance. I've been on two 2000 mile trips up to the Oregon campout and it averages around 25 mpg.
If you're going to hook yours back up you should suck on the hose connected to the module and see if the arm moves. I'd guess you've got a blown diphragm also, in which case you'd need to cap off the little nipple on the plenum so that you're not getting a vacuum leak.
Ron

[majicwrench]

Vacuum advance is an important item for mileage, and should be made operational. It has no effect on power. Along with the mileage improvement, the oil will stay a tad cleaner.
Keith

[maytag]

Vacuum advance ...... has no effect on power. Keith

??
OKAY...I'll admit that You've got me here.
Maybe not peak hp, but it CERTAINLY has an impact on teh HP curve, wouldn't you agree? Which means depending on throttle position and / or rpm's, you'll see a significant difference in power..... agreed?

[johnssi]

Thanks for all the comments everyone. I'll try your suggestion Ron and see if the diaphragm is blown. Could it affect the idle speed at different stages of warm up?

[majicwrench]

Not sure if vacuum port for advance has manifold or ported vacuum. If manifold vacuum, yes, it will affect idle speed.

Maytag,
Agree a little.... depending.... at full throttle or any hard accelleration, vacuum advance does nothing, as all the vacuum is gone. Anything less than full throttle, and esp at cruise, yes, the vacuum advance helps the engine run to it's potential.

Vacuum advance was put there for good reason, and if possible should be operational.
Keith

[maytag]

Not sure if vacuum port for advance has manifold or ported vacuum. If manifold vacuum, yes, it will affect idle speed.

Maytag,
Agree a little.... depending.... at full throttle or any hard accelleration, vacuum advance does nothing, as all the vacuum is gone. Anything less than full throttle, and esp at cruise, yes, the vacuum advance helps the engine run to it's potential.

Vacuum advance was put there for good reason, and if possible should be operational.
Keith

AGREED. 100%!