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Author Topic: WO Carb Choke plate position while idling  (Read 3797 times)

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Offline maximushuntermus

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WO Carb Choke plate position while idling
« on: September 02, 2013, 06:01:19 PM »
My jeep doesn't seem to want to idle down right unless the choke plate is canted maybe 45 degrees or more, this is after warm up by the way, seems like in a perfect world it should be straight up with no restriction. If that be a true statement could it be possible I need a bigger idle jet or something. Also note I'm in Arizona at about 7500' above sea level.

Offline maximushuntermus

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Re: WO Carb Choke plate position while idling
« Reply #1 on: September 02, 2013, 08:12:08 PM »
Update, if I remove the vacumn line to the crank case and plug the intake vaccum, its happy. I had ordered a new pcv valve from Walcks but when I got it it was empty, as in no spring or anything in it, so I called to ask what up and was told they were a souce of trouble getting pluged up so most guys just drilled them out. Could this be the problem? what size orrifice should be in the pcv valve or restrictor in this case.
Or is this a symtom of a greater problem?

Offline 1955CJ-5

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Re: WO Carb Choke plate position while idling
« Reply #2 on: September 02, 2013, 08:24:17 PM »
Mine had a spring and plunger...I took it apart and cleaned it and it works fine...

It sure would lean out your mixture if the orifice was too large...

Can you detect any positive pressure from the crankcase end of the vacuum line? There might be a lot of blow-by......

http://www.film.queensu.ca/CJ3B/Photos/Tech/PCV/CrankcaseVentilation.jpg
« Last Edit: September 02, 2013, 08:27:15 PM by 1955CJ-5 »
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Offline scoutpilot

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Re: WO Carb Choke plate position while idling
« Reply #3 on: September 03, 2013, 06:31:13 AM »
A carb that requires some choke to idle has a vacuum leak. Get a can of starting fluid and with the motor idling at normal temperature, spray the fluid on the carb in short bursts at every angle from top to bottom. Pay close attention to the manifold/throttle base gasket (it should be a diffuser gasket, properly tightened) and to both ends of the throttle shaft. Pause briefly between bursts. Listen to the motor. If the RPM changes, you have a vacuum leak. It could be as simple as tightening a nut or screw to stop it. If it leaks at the throttle shaft, you will probably need bushings and a better shaft. As well, you may want to check your needle valve. At your altitude you need a #548 needle. If it is a #547 you are running too rich.As far as the PCV valve is concerned, the only reason to remove the spring and plunger is sludge buildup. The only reason for that is neglecting to perform regular, routine maintenance.
« Last Edit: September 03, 2013, 06:33:07 AM by scoutpilot »
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Offline maximushuntermus

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Re: WO Carb Choke plate position while idling
« Reply #4 on: September 03, 2013, 11:26:51 AM »
Thanks guys, I stumbled onto some of your info "scoutpilot" on the 2a page and did just that sprayed WD looking for a leak and found nothing. So I pulled the vacuum line off the pcv at the intake and with the intake plugged everything idles great, the pcv valve looked like it had a 1/4" hole drilled thru it. I have a new PCV valve ordered and on its way so I'm sure hoping this will fix it.
No pressure from crankcase, just rebuilt motor so were good there, thanks for info on the different size needles as well.

Offline scoutpilot

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Re: WO Carb Choke plate position while idling
« Reply #5 on: September 03, 2013, 11:59:07 AM »
WD-40 is not volatile enough. You need either propane or starting fluid. No vacuum line attaches to the PCV. A tube does connect it to the valve cover. The pressure in the crankcase is low, but enough to cause problems. . It is strong enough to push the gases and moisture from a cold crankcase to the intake.
« Last Edit: September 03, 2013, 12:00:37 PM by scoutpilot »
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Offline maximushuntermus

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Re: WO Carb Choke plate position while idling
« Reply #6 on: September 03, 2013, 12:28:33 PM »
OK I will get some starting fluid, yeah your right the pcv valve screws right into the intake where there is vaccum so I pulled the hard line off the elbow. Sorry at work and hurrying, got to go thanks for your help, I do appreciate your time.