vacuum advance
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New User
Joined: Jul 2011
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vacuum advance
352 vacuum advance-If I suck on the tube I feel like i have free flow, and I see no movement in distributer. I usume it is bad. The symptoms I am seeing is a hesitation (nearly stall) when thottle is depressed quickly especially when coming up from idle. Applying partial choke helps the problem but problem persits at all engine and ambient temps. Would a bad vac advance cause this? from previous posts I read from some that the vac advance really only has an effect in the mid range rather than low rpm.
Accel pump squirts when accuated and i have tried different positions on the linkage with no real difference.
Heat riser valve appears normal (springs back etc.) and is intact, but not really sure what else to look for.
thanks
cleaned-air filter new-fuel filter, points, cond, rotor, plugs, timing checked and initial set for 10. I dont have a tach but I feel im "in the ball park"
Accel pump squirts when accuated and i have tried different positions on the linkage with no real difference.
Heat riser valve appears normal (springs back etc.) and is intact, but not really sure what else to look for.
thanks
cleaned-air filter new-fuel filter, points, cond, rotor, plugs, timing checked and initial set for 10. I dont have a tach but I feel im "in the ball park"
Senior User
Joined: Sep 2010
Posts: 102
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From: Hendricks County, Indiana
Well, I'd like to keep an eye on this and see what you find out because I'm having a similar problem with my 292. The old Y-block just falls on it's face when I hit the accelerator.
A friend of mine who is a Ford technician told me it could also be an air/fuel mixture problem (especially if it has been moved to a different climate, as mine was). It might now hurt to look into that too, although it looks like you've already done more due diligence than I have so far.
A friend of mine who is a Ford technician told me it could also be an air/fuel mixture problem (especially if it has been moved to a different climate, as mine was). It might now hurt to look into that too, although it looks like you've already done more due diligence than I have so far.
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mixture
my thought on mixture is that possibly the free flow of air from vac advance may be leaning the carb out. when i plug the hole on carb the problem is slightly diminished but still exists. i am think its a combination of things.
Junior User
Joined: Jun 2003
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From: Centralia, WA
With the cap and rotor out of the way, make sure the plate in the distributor that the points are attached to moves. There is a little bar connecting it to the vacuum advance diaphragm. If it moves smoothly you should hear air moving in the tube as the diaphragm moves. Sucking on it may not produce enough vacuum to move the plate very far, but it should. If you just suck in air with no resistance then the diaphragm is probably bad. This will cause stumble on acceleration.
You can get just the vacuum diaphragm itself, but since you're working with the distributor anyway, I would recommend pulling it out and checking the driven gear at the bottom (or moreso the roll pin that holds it on) and the shaft bushings. If the shaft has a lot of play in it you might as well get a whole distributor, they aren't expensive.
You can get just the vacuum diaphragm itself, but since you're working with the distributor anyway, I would recommend pulling it out and checking the driven gear at the bottom (or moreso the roll pin that holds it on) and the shaft bushings. If the shaft has a lot of play in it you might as well get a whole distributor, they aren't expensive.
Posting Guru
Joined: Mar 2006
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when you stomp the gas, engine vacuum drops off, meaning the vacuum advance would be doing nothing to begin with. so- it sounds more like a fuel issue, even though you've already checked the accelerator pump. maybe a larger pump is in order?
i think your diaphragm would have to be REALLY torn up (missing, even?) to allow enough airflow to mess up the mixture, but you should fix it, either way.
i think your diaphragm would have to be REALLY torn up (missing, even?) to allow enough airflow to mess up the mixture, but you should fix it, either way.
Cargo Master
Joined: Jul 2006
Posts: 3,014
Likes: 91
From: Concord, CA
If you really want to know for sure then cap off the vacuum advance line at the carb port. Then run the engine and if your problem persists you now know. If the diaphragm is shot then there is nothing to stop air from moving into the engine along that line.
Tuned
Joined: Feb 2005
Posts: 283
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From: Monroe NJ
Try removing the pcv valve and putting tape over the hole and see if that helps, might have a vacumn leak somewhere. Worked for me. Tom
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Freshman User
Joined: Dec 2009
Posts: 33
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From: central NJ
vacuum
The only solution for my 50 F-1 was to use Gumout© with Regane in the fuel tank to clear up the awful gas with 10% alcohol. It took awhile, plus I replaced the vacuum advance which had a leak. The hesitation was so bad I could not drive it, good luck. Pete
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