Best Port to Check Vacuum on 1983 W250?
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Professional
Joined: Aug 2020
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Best Port to Check Vacuum on 1983 W250?
This truck is the U Code 4 barrel Thermoquad 318 with lots of vac lines. I need a baseline port to check general vacuum - any port below throttle plate or? Thanks!
Grand Champion
Joined: May 2019
Posts: 5,158
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From: S.W. Indiana
Look towards the rear of the intake and see if there is a manifold with several vacuum lines on it. I always like to read an engine with manifold vacuum. If there is a rubber cap on one, check it there. If there isn't an unused port, use some hose with a tee to check it. Checking on the carb. you sometimes don't get full vacuum pressure.