Dumb Question: Vacuum system..
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Freshman User
Joined: Feb 2003
Posts: 38
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Dumb Question: Vacuum system..
Ok, don't laugh... I understand a lot about engines, but I've never had a good grasp on the vacuum system...
Here's what I understand - let me know if I'm right or wrong.. The engine is basically an air pump. As the pistons go up and down, they suck air in. If the throttle plate is closed, a vacuum is created in the ports of the intake manifold and cylinder heads... As the throttle is opened up, the amount of vacuum is reduced because more air can flow into the vacuum...
A hose taps into the intake manifold somewhere and runs to a vacuum canister where this vacuum is "stored" and regulated. From that canister, hoses are routed to various gizmos (regulators, timing advance, etc...) that use the amount of vacuum as a signal for what to do..
The big thing I want to understand is the relationship between throttle position & amount of vacuum. More throttle = less vacuum, right? How much vacuum is the right amount on a 302 EEC-IV?
Here's what I understand - let me know if I'm right or wrong.. The engine is basically an air pump. As the pistons go up and down, they suck air in. If the throttle plate is closed, a vacuum is created in the ports of the intake manifold and cylinder heads... As the throttle is opened up, the amount of vacuum is reduced because more air can flow into the vacuum...
A hose taps into the intake manifold somewhere and runs to a vacuum canister where this vacuum is "stored" and regulated. From that canister, hoses are routed to various gizmos (regulators, timing advance, etc...) that use the amount of vacuum as a signal for what to do..
The big thing I want to understand is the relationship between throttle position & amount of vacuum. More throttle = less vacuum, right? How much vacuum is the right amount on a 302 EEC-IV?
Laughing Gas
Joined: Mar 2003
Posts: 877
Likes: 1
From: Colorado, U.S.A!
You've got a pretty good grasp on it. Some items, such as the A/C routing doors (or whatever they're called), use the canisters, others connect directly to the intake manifold.
I think the vacuum at idle should be somewhere in the 17" to 21" range. Subtract 1" from that for every 1,000 feet above sea level.
I think the vacuum at idle should be somewhere in the 17" to 21" range. Subtract 1" from that for every 1,000 feet above sea level.
