Question about 1987 Jeep Wrangler

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Weber carb vacuum lines

I bought an 87 Wrangler with 4.2L to which a previous owner had added a Weber carb. The vacuum hoses aren't hooked up at all like the repair manual shows. I'm trying to figure out if the vacuum advance and the vacuum line to that engages the 4wd are hooked up correctly to the Weber. The vacuum advance is connected to a port at the base of the carb just below the automatic choke. The 4wd line is connected about 2'' left of where the fuel goes into the carb if you're standing in front of the Jeep.

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Hookups vary from carb to carb. there are two kinds of vacuum: full signal at all times from the manifold or carb base, and delayed: vacuum that only is present with the throttle either closed or open (depending upon way the carb is internally ported.) I'm fairly certain that vacuum to the t case is full signal. vacuum to the advance is an either or thing. Some engines "like" full vacuum there, others don't. It's easy to tell though...if the engine wants to "lay down" when taking off from a standstill with advance attached one way, attach the other way and see if it makes a difference. Also you can check MPG in different positions and decide what works best if no "off the line" difference is observed. Make sure that the advance diaphragm is good or nothing will work correctly either way.

Posted on Nov 16, 2009


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