Vacuum Test
1 - 10 of 10 Posts
In order to test for a restricted exhaust system, connect a vacuum guage (autozone has them for 24.99), to a manifold vacuum source. Increase the engine speed to 2000 RPMs. Watch the vacuum reading. If the vacuum steadily decreases, then the exhaust system is likely restricted.
Joined
·
21 Posts
Where would that manifold vacuum source be located exactly if you don`t mind my asking ?
Joined
·
21 Posts
What would be the signs to look for in order to suspect a plugged cat ?
Joined
·
798 Posts
Low engine power, excessive heat before the cat plus the cat itself.
The cat might even turn cherry red if it's totally blocked.
Joined
·
104 Posts
Engine vac is measured form the intake manifold or base plate of your carb (not the same port used for vac adv distributor).
![]()
http://www.fordforumsonline.com/forum/members/6dsick-albums-new-stuff-picture382-vac-set-20hg.html
A normal vac reading should be around a steady 15-20Hg (Hg=inches of mercury not PSI) for an engine with a factory spec cam shaft. With a bigger cam the reading will be lower and lobbing.
For a fuel injected motor, you should be able to find a vac port somewhere on the manifold, usually near the brake booster port.
A normal vac reading should be around a steady 15-20Hg (Hg=inches of mercury not PSI) for an engine with a factory spec cam shaft. With a bigger cam the reading will be lower and lobbing.
For a fuel injected motor, you should be able to find a vac port somewhere on the manifold, usually near the brake booster port.
1 - 10 of 10 Posts
Join the discussion
