Mercury Cougar Owners banner

1 - 5 of 5 Posts

·
Registered
Joined
·
3,320 Posts
Discussion Starter #1
I'm getting a little hesitation from a dead stop when first accellerating on the ol'302 2V..

I know I have to replace the vacuum advance (did the mouth test) but I thought that it was more for advancing timing with hard accelleration/pump to the carb.

Is this a typical symptom? I'm getting really good response out on the road up and running, just not so good with the initial takeoffs..

Motor is timed right and carb/points all operating well, otherwise..


Thoughts?

Thanks!
 

·
Registered
Joined
·
173 Posts
first burn out i did on my rebuild blew out my vacuum advance. it was the origional distrubutor musta blew the old seal in it or somthing. im not too familiar with it. but right after the burn out it bogged way down had to fight with it to get it to run the last 30 feet into my drive way. before i did the burn out and replaced the distributor it would back fire when i put my foot into it a little taking off pretty quick or if i was already up to speed and wanted to accelerate faster i could hear it almost sound like tapping coming out of the exhaust. but with the vacuum advanced fixed i no longer have that issue. id replace it either way if its the origional. one less thing to worry about later on.
good luck.
 

·
Registered
Joined
·
5,633 Posts
The vacuum connection to the vacuum advance is called a "timed" port. There will be no vacuum here at idle. The vacuum "times" on as soon as you are just off idle. So when you have a bad vac advance diaphragm, you end up with a timed vacuum leak. Ordinarily this is not a big deal, but it can cause the mixture to go lean right off idle and you do not get the advantage of the slight increase in timing advance when the vacuum kicks in.

You can determine if this is the cause of your flat spot by just replacing the bad advance module. You were going to replace it anyway, right? As a quicker but not completely accurate test, you can block off the vacuum port at the carb. This will address the mixture issue, but not the timing issue.

Given all of that, a flat spot off idle is usually caused by the accelerator pump being improperly adjusted (fuel shot comes in too late) or not enough base timing, or the idle mixture being too lean to start with.
 

·
Registered
Joined
·
11,950 Posts
Bill hit it on the nose. Could be a mixture if the 2 but if you wanna replace the diaphragm anyway try it first. What the heck. Could depend on how hard you are leaving as well...
 

·
Registered
Joined
·
3,320 Posts
Discussion Starter #5
Thanks Guys..I'm gettin' somewhere here!

B
 
1 - 5 of 5 Posts
Top