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bad vacuum reading 12.5" idle?


Joined
Oct 4, 2011
Messages
12
Vehicle Year
83
Transmission
Automatic
Hello ive got a 83 ranger with a durasparked 2.8 automatic 3spd anyways has number 46 jets in carb too try too get gas mileage and i do lots of interstate driving and plugs are burning a tanish color and seems too be burning just right and have done a complete tuneup got all new ignition plugs gapped .44 and yet when engine is cold has only 10" and when warms up has around 12.5 at idle and ive got my timing with advance unhooked during test at 12degress timing. Ive tried using starter fluid too see if i got a leak anywheres and havent found nothing I blocked egr off due too no computer anymore what could be problem? It dont get good gas mileage 11mpg hwy lol any suggestions? Ive dialed in my a/f needles too the highest vacuum possible is there anything i can do too get more vacuum help please thanks..:icon_confused:
 
While the engine is running take a length of vacuum hose and put one end up to your ear and search around with the other end. check everywhere a vacuum leak could be. If you are using a non feedback 2150 carb on the choke thermostat housing is the preheater tube fitting that needs to be plugged or capped it goes down at a 45 degree angle toward the dizzy. if the fitting is still there cap it with a 5/16s refrigerant cap or pull the fitting off and put a plug in there. Another one that is hard to see is on the back of the intake manifold below center of the carb. It was used for the vapor system I just put a restrictor in line from it to the cannister so it still pulls the vapors into the engine. The vacuum hose works good for isolating vacuum leaks and exhaust leaks the closer you get the louder the hissing. Just stick it in the carb when running so you know what to listen for. Be careful of moving parts. GL By the way my advance is hooked up to manifold vacuum. Time it at 10 degrees with the advance disconnected and plugged. Then hook the advance up to manifold vacuum and adjust the idle air screws for the highest vacuum pressure. It has worked for me for over two years now turn key and go.
 
It may take a couple times getting the air fuel in sync with the timing. With the vacuum advance on manifold vacuum you should be sitting at 20 degrees at an idle adjust both air fuel needles for the highest lean setting turn them out and back in until the vacuum starts dropping then back out. Check that they are within half a turn between them count the turns in to lightly seated then back out. If they are not within half a turn of each other you have carb/vacuum issues. Adjust the idle speed then do the air fuel again until the vacuum only drops when you turn the idle air screws in. Make sure the choke is fully open and the engine is up to temp before making any adjustments then after the engine is cold you can adjust the high idle and choke spring tension.
 

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