New (to me) 1994 Disco. The vacuum advance hose comes out of the plenum but is just cut off. I bought new hose tonight to put on tomorrow. The port (on the distributor) where I'm supposed put the hose actually has cap on it.... My guess is that the distributor was replaced at some point and the hose was never installed. The truck doesn't idle right when its warm. Likes to surge then drop to the point where it stalls. Would this unattached hose cause this? (vacuum leak, vacuum advance, etc.) Any thoughts would be helpful. Thanks in advance.

 

Um, vacuum advance has everything to do with idle performance since vacuum is highest with the throttle plate closed. The centrifugal weights come into the picture once the throttle plate is opened. There are three items to check on besides reconnecting the disconnected vacuum advance, PCV system is working, no vacuum leaks from intake/valley pan and idle air control. Of course you should be checking the timing with a light (which requires the vacuum advance to be plugged)(how ironic)......

 

and while you're at it, check to see that the vac advance actually works, the diaphrams are known to go bad.....maybe it was bad and somebody just capped it off for whatever reason....fairly easy to replace though..

 

ihscouts-this is true if the 94 Disco does not utilize Ported Vacuum.
I deleted my post, because I was with the understanding that the 94 Disco utilized "ported vacuum" in which there is no vacuum at idle and only used for fuel economy at part throttle.
If the vacuum is pulled after the throttle plate it works during idle. If it taken before the throttle plate it is "ported vacuum" and will not show vacuum at idle, but will at part throttle
So I will say, check to see if there is indeed vacuum at idle, if there is, then the info I first posted would have been wrong.
If there is no vacuum at idle, but there is at part throttle, then my post would have been correct.
If there is NO vacuum at idle, coming from the line going to the distributor, then it will not have any effect on idle.

 

Yep, understood and honestly I didn't enjoy saying otherwise, much respect for you bud. Besides, I hate distributors! The vacuum line in this case for the vacuum advance is pulled from on top of the plenum, just behind the throttle plate as it opens, couldn't have put it any closer to calling it ported.

 

The funny part is it's been left obvious. If I had seen this while being a prospective buyer I would've owned it CHEAP! Atlantic British wants $189.95 for a vacuum advance pot...... Paddock Spares wants $74 not including shipping and it's OE.

 

Thanks for the help. I'll let you know if anything changes when i get the hose installed.


This is the first disco I've ever owned. I should have done a more thorough inspection. Don't think i could have got it much cheaper... $1000.

 

The respect is mutual. I kind of generalized on my original post and could have went in a little depth on the subject of vacuum advance setups. I cut my teeth on the old school setup, where the vacuum advance was used as you were referring to.
Now to check on my muffler bearings.