vacuum advance not working?

[durkzz8]

i have a 65 Falcon with a 170. i am about to install the petronix unit. in the instructions it says to make sure the vacuum advance is working properly. so i unhooked the line on the carb side and revved the motor and it revved just like it always had. the carb was sucking air, so i guess it is messed up in the dist. is there a common problem with these? the car sat for about 15 years, after rebuilding the carb it fired right up. could something in the dist. just be rusted up from the car sitting so long?

Chad

 

[addo]

It'll be a vacuum-only distributor. Free revving doesn't really put any load on the motor, so lugging it uphill at modest speed would be a better test. You need to plug the pipe into your carb to do this, or the resulting air leak will flavour results.

Also, I'm assuming it's an original carb and distributor.

Regards, Adam.

 

[CZLN6]

Howdy Chad:

We just went through this with Ledition back on Dec 6 & 7. Scroll back or do a search entitled, "Vacuum Advance Not Working" and you'll find it.

If you can't get ti done that way, let me know and I'll repeat it here for you.

Adios, David

 

[Anonymous]

Let me know what you find, I haven't worked on mine yet. I'm curious to find out weather you can feel resistance when your sucking on the end of the hose to the distributor.


Note: I hope no one is offended by the above sentance, but thats really the only way to say it, I'm not trying to be offensive.

Note Note: 100 posts, YEAH! I think i'm going to celebrate by getting another cup of coffee!

 

[durkzz8]

I tried the sucking on the hose thing. I sucked for about 2 sec. before it seemed that i was sucking nothing. Also no movement on the arm. Then I unplugged the vaccum advance from the dist. and drove it about 10 miles and it drives just like it always has. I am guessing it is just the advance is stuck. Is there anyway to lossen it up?

 

[66 Fastback]

If you pop the cap off the distributor and suck on the hose to the distributor, you should 1 see the are attached to the diaphram move the plate on the inside of the distributor. You should also note whether or not the diaphram is holding vacuum. If you can continue to suck, you likely have a bad diaphram and need a new vacuum motor.

Another test with the engine running is if you put a plug over the fitting on the carb and suck on the hose to the vacuum diaphram, you should be able to change the engine speed as the timing advances. Again, if it does not hold a vacuum, then the diaphram is likely leaking.

If it is holding vacuum and nothing is moving on the distributor, then it may be seized up and you probably need to disassemble and clean the distributor.
Doug