Vacuum Test
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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.
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Where would that manifold vacuum source be located exactly if you don`t mind my asking ?
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What would be the signs to look for in order to suspect a plugged cat ?
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Low engine power, excessive heat before the cat plus the cat itself.
The cat might even turn cherry red if it's totally blocked.
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Engine vac is measured form the intake manifold or base plate of your carb (not the same port used for vac adv distributor).
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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.
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