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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Re: Weber carb vacuum lines
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.
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The idle mixture screws do not control the idle. Is there no idle screw? If you have an anti-dieseling solenoid on the idle screw, make sure it is coming on with the ignition switch and use it to adjust the idle. Set the idle and then adjust the misture screws to maximize intake vacuum at idle. Readjust the idle after adjusting the idle mixture. The port at the back of the carb is not used in all systems. If you have a distributor with vacuum advance, make sure the correct carb post is connected to the distribtor. Adjust the choke and fast idle to engage when the engine is cold.
When attaching vacuum lines, you need to remember only one thing. Mark each hose when you remove it from the original carb (quadrajet?) Hoses that attach to the baseplate are at full vacuum and should be returned to a similar location or to the manifold, using a "tree". Hoses that are connected to the body of the original carb only see vacuum when the throttle is opened. Those can be attached to the fitting on the right side of the front metering block. Most Holley carbs have no provision for the valve located at the front of early Q jets (bowl purge) nor do they have any electrical connections except for the choke mechanism. The most important vaccuum line is the one for your power brakes. Make sure that one is firmly connected either to the rear of the carb baseplate or the manifold. All other lines are nowhere as critical as that one is..
Depending on your carb, distributor and transmission, you have from zero to two vacuum hoses.
If you have an Autostick transmission, there's a vacuum hose running from a port in the intake manifold to the control valve on the left side wall of the engine bay. (Hint: if you've got a car that came with Autostick and that someone's converted to manual transmission, the bracket for the control valve is the perfect place for your coil.) Most people don't have this transmission even if their car came with it--it's only a three-speed and it's hard to find parts for it, so most of those cars have been converted to manual transmission.
The other hose you might have is for your distributor. The port is on the left side of the carb, and a hose runs between it and the metal vacuum advance can on the side of the distributor. If you have a 009 distributor or an aftermarket distributor like an MSD you don't have the vacuum advance can; if you have an aftermarket carb like a Weber you don't have the port. Therefore...you probably don't have any vacuum lines on your engine.
if only one vacuum line then?
the vacuum line goes from the vacuum advance on the side of the dizzy, to the carburettor, just around the throttle linkage if i recall. hope this helps.
TRY TURNING THE DISTRIBUTOR A LITTLE AFTER YOU LOOSEN THE BOLTS TO ADVANCE THE TIMING . DON'T LOOSEN THE DISTRIBUTOR TOO MUCH, JUST ENOUGH TO TURN . BUY A CHILTON MANUEL ON YOUR JEEP TO MAKE SURE THE VACUUM LINES ARE RIGHT
These jeeps are carbeurated, with heavy emissions systems forced down the throats of Jeep. There are insane Vacuum systems that are too complex to deal with. What I did, (I have the 4.2L) was go out and purchase the Weber kit. I am not selling the part for them, I am actually a happy owner. Mine would die every time I came to a stop. I swapped out the junk and popped in the Weber. I have had no carb problems what so ever. I even eliminated the messy vacuum system! I payed about 200 bucks on Ebay, but from Weber direct they cost around 300. Good luck!