Thats $50 for the vacuum advance control not the whole dizzy. I am going to take another look in an hour or so

Ok so I looked at the dizzy again. Yes it moves smoothly turning it clockwise with my hand. I tried sucking on the vacuum advance and there is no way it will move. I ran the car and with my finger over the vacuum hose I noted that there is vacuum but only when I rev the engine, this sounds correct to me. So now do I buy a new vacuum advance dashpot or no. The inside of the distributor is a little grimey is there a safe way to clean it?

Edited June 9, 201114 yr by grantf

only buy a vacuum advance dashpot after you have hooked up a mighty vac, put 18" of vacuum on it and observed correct advance.

cozye that sounds like the right thing to do by not throwing $$$ at a problem that may not exist but what is a mighty vac??

... or you might be able to apply the engine vacuum from another car to your Z's vacuum advance, via a long tube.

Mighty vac = hand vacuum pump

You should have one anyway, they are great for bleeding brakes, clutches, troubleshooting dash pots, testing for leaks, etc..

http://www.harborfreight.com/mityvac-vacuum-pump-39522.html

the vacuum advance on our car is connected on the low vacuum side of the throttle body, for a quick test, you could rig a vacuum line off a T from your FPR vacuum line, and at idle you should be around 17-18", connect it to your advance while running, and observe timing change with a timing light. If it jumps up a bit (like 7 degrees I think?) then it's working. If it doesn't move at all, then its not working. Just be careful though, because reving the motor beyond a certain rpm will trigger the mechanical advance as well. Just make sure it stays at about idle when you do it, it will move up some due to the advance but not a lot.

Ok I got a mityvac it cost a little less than a new vacuum advance diaphragm dash pot thingy. I hooked it up and observed the distributor advance operate normally at around 11 in.HG it moved about 5 to 10 deg clockwise. This was with the cap off and the engine not running. Also I calculated my MPG 3 times by filling it up to exactly 10 gallons and noting the mileage before and after, I get between 11 and 12 mpg :ogre: I have not tested the timing with the mityvac yet, but I am thinking that there must be another path to go down to solve the bad mileage. Any suggestions?

Oh by the way when I apply vacuum to the dashpot thingy it does not hold a vacuum it returns is this normal? There really is not much in the FSM regarding this.

Edited June 23, 201114 yr by grantf

here are my plugs, they look really black, dry execpt some oily fluid around the theads. Am I running rich?

Oh and I accidentally broke #4 not sure how that happened. new plugs are gapped and installed.

Edited June 24, 201114 yr by grantf

They definitely look rich. I've mentioned this before, but on my 1976 engine my FPR showed good pressure when cold but when the engine got hot it caused high fuel pressure. Have you checked fuel pressure when the engine is nice and hot and have you confirmed that the FPR reacts to intake vacuum? You should get ~36 psi with the FPR vacuum hose disconnected and ~28 - 30 psi at idle with ti connected. The low pressure at idle will also be there at cruise, lowering gas usage.

The best way to check your sensors is at the ECU plug, using the numbers from the FSM Engine Fuel section.

you are running rich going by the plugs.

You are saying that the vacuum advance dashpot leaks ? When you have mighty vac on it at 10in, it doesn't stay in the same place ? I believe that would be leaking and you may want to replace. I don't think that's your issue though.

What vacuum is your engine pulling while running ?

I would check water temp sensor for correct operation, check for thermostat correct operation, check TPS switch. Also make sure your CSV isn't leaking and that it's operating correctly. I'd be willing to bet it's one of these things assuming no one has messed with your AFM.

Sounds like your vacuum advance is takin a crap, they suck I disabled mine and drilled out the t-bar and added lighter springs... much simpler and very effective...

As for running rich or lean, at high rpms? low? After 30+ years these afms DO need to be adjusted... its just a spring, and adjust them WORKS WONDERS. You can replace perfectly fine parts all day with new ones... or just adjust a 30+ year old EFI system.... its ancient, and kind of like a carb as is it does get dirty and takes mechanical readings on volume and meters air with flaps and bypass n such...

The bypass screw is an actual bypass screw, so the more it is closed, the more air is actually pushed through the meter, resulting in a richer mixture.

So enriching or leaning out the mixture take this for example - I was running lean at top, and much better at lower rpms IF i tightened the bypass, because it has a great affect at idle and has less effect for the more air that is actually being pushed through and metered at high RPMS with high air flow. So all i had to do was turn the spring CCW inside the afm about 4 teeth or so, then open my bypass more for a leaner mixture at idle and up.

(BTW, do not close your bypass screw all the way doing this, you very well may damage your afm and flap because the bypass screw acts as an escape at rapid deceleration... or your flap goes FLAP FLAP FLAP and bounces around, which is a no-no)