Where does the vacuum advance connect?
 

Sorry I feel kinda stupid...

Putting my truck back together after a headgasket job, and thought I labeled the pretty minimal amount of vacuum lines well enough, but I guess not.

I have a 1978 20R engine, the distributer with only one vacuum hose coming off of it. Not a california emissions system.

I honestly can't remember where the other end connects to...searched around and looked at photos of engines and other vacuum diagrams that have been posted, but I can't tell where the line connects to in some of the diagrams I've found. There are places where multiple lines cross in those diagrams, and I can't quite tell which is which after they cross in some places...

Any help?

I assume that this is not desmogged?? You can just connect it directly to the carb. I'm sure that that it plugs into one of the pesky hardlines, but as long as it connects directly to the carb somehow you shouldn't have a problem.

Do you have emissions around you neck of the woods?

Correct, it is not desmogged.

Well...connect it to the carb where? Any old place on the carb?? If so...if you have the time, please explain why!

It would be nice to actually understand my vacuum system...but there are too many things I'm actually interested in that I don't have time for! :)

There should be a port on the actual carb for you to connect to. The vacuum advance simply advances the timing at higher RPMs so that your spark comes sooner in order to propery ignite the air/fuel as the piston returns on the compression stroke. It basically give the engine time to fully ignite the mix. If your timing does not advance then you'll experience a lack of power, unburnt fuel leaving through the exhaust and possibily misfires.

Well there are a bunch of ports on the carb, just wondering if you were saying I could attach it to any of them, or what.

I looked at a couple photos I took before I starting taking things apart and I think I've got it in the right place.

Thanks!

You should be able to plug into any one of them. I believe they all pull the same vacuum relative to the increase in RPMs

Gotcha. Thanks!

If you get it right, it will advance your timing when you rev the motor. So that's an easy way to test if you found a good port. I mean, it will do it above and beyond your centrifigal advance. So test it with and without the line hooked up.