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  • I-6 running like a champ now.....eliminate vaccum

    We were out muddin pretty hard and doing some mud drags a couple weeks ago.....my entire air cleaner was full of water and oil.......oil from the pcv valve and water from the puddles.....

    Anyway.....one of the guys said to just eliminate all that vacuum stuff and only keep the vacuum advance on the dist..... so today i tackled that....i was weary at first with removing all those damn tubes....wow...like 20 lines or more....

    So i get them all removed....capped the rest coming out of the carb and intake....there must be about 6-7 of them that u have to cap off....two or three large ones for sure.....took out the canister and the other canister under the battery....

    Wow...this thing idles great...it used to die if it wasnt warmed up....now its smooth as every and you cant tell its running at all.....what a difference and now the vacuum advance seems to actually work!!!!!

    I replaced the pcv with an open element filter and plugged the other hole in the valve cover that used to go to the air cleaner......Looks a million times better under there now.......

  • #2
    where you trailering your CJ up by H2Otown today?
    i was doing some mapping up there and saw a nice lifted blue cj (covered in mud) being trailered south

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    • #3
      I replaced the pcv with an open element filter and plugged the other hole in the valve cover that used to go to the air cleaner......Looks a million times better under there now.......
      Sure for a little while.

      I would not eliminate the PCV valve. Your engine should run and idle gret with it connected. Without it your engine is going to look like the bottom of a mud pit.

      As far bak as the 1950's they had some means of drawing fresh air into the crankcase and venting the fumes. They originally used road draft tubes but t doesn't work as well as a PCV. Some people use their headers to evacuate the crankcase. Your going to need something.

      Also, are you running the stock air cleaner? If you are the you have to remove the air passage doors because without any vacuum they will shut and block off the clow of air to the carb. Probably not a problem at idle but when running under load your going to runn a lot richer.
      Last edited by John Strenk; 07-04-2006, 08:49 AM.

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      • #4
        Originally posted by SD Boy
        where you trailering your CJ up by H2Otown today?
        i was doing some mapping up there and saw a nice lifted blue cj (covered in mud) being trailered south
        No that was not me....but.....

        It was my friend Dana.....his is about 3" taller than mine......ya gotta come see these crazy things in action......his has a 350 with some really stout cam in it....it barely stays running.....all kinds of power....

        If you looked closey his liscense plates read "IT"......he did this because he always gets "IT" stuck.....breaks "IT" or "IT" just died......

        By the way.....we have the only big jeeps around here in Sioux falls.....all the others are just babies and need a lot of watering......we have only found one bigger jeep here in town and i dont think its street legal.......44x19.50 15 boggers.......totally rusted out and has stock axles......he wants $10,000......hahaha we lust laugh and laugh.....the jeep is worth about $800 and the tires are worth $2200.......so at max its worth $3000 You may have seen a similar yellow jeep in watertown its almost the same thing but it at least has 2.5 ton rockwells under it.......


        Ok....now what with the pcv valve?? I have a small block 400 in my monte carlo and it doesnt have one....just two breathers......why wouldnt the open element work??? or do you mean it will pump oil out of it???thats not really a problem since its covered in oil, a nice thick slurry with dirt and mud stuck on it.......I was going to get the breathers with the hose adapter and that is what u run into the exhaust right??

        Oh....i guess my 304 doesnt have one either.....there are no holes in the valve covers..??? Whats going on there?? The oil filler cap seems to be a breather though......
        Last edited by Jodean; 07-04-2006, 11:23 AM.

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        • #5
          The 304 does have a PCV valve.
          http://www.jedi.com/obiwan/jeep/wago.../pcv_i6_v8.png

          What year Monte? Every year I looked up had some type of ventalation system for the crankcase. Or did you put this engine in yourself?

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          • #6
            ok, i have a pcv on my 304 but it does go back into the carb.....not the air cleaner.....just like the diagram you show.....the I-6 seems to go to the air cleaner.....oh i guess it goes to the intake.....not sure if mine did that when i first got it.....

            My monte is an 86 and ya its a 70's 400 small block.....im pretty sure about 99.5% sure that there is only two breathers, one on either valve cover and no pcv.....is this going to hurt something?? the car isnt here right now, but i can check later......

            So what should i do with the pcv and why doesnt the breather take care of it..?

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            • #7
              The breather is a fresh air filter.

              The PCV valve is a crankcase purge system. It pulls vacuum on the crankcase which in turn pulls air in the breather.

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              • #8
                The breather is a fresh air filter.
                Unless your engine is old and tired like mine, in which case it is used an orifiice to spit oil and gunk into the air cleaner and ruin perfectly good air filters!

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                • #9
                  Originally posted by jeepwhore
                  Unless your engine is old and tired like mine, in which case it is used an orifiice to spit oil and gunk into the air cleaner and ruin perfectly good air filters!
                  This is exaclty what mine is doing....thats why i got rid of it.....it was just burning like a 2 stroke......only run it in the mud so im not really worried about it, its not like im going to get 10,000 miles on it in the next 10 years....maybe half that.....

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                  • #10
                    I have been contemplating doing this for a while. A friend of mine helped his boss do it on a scrambler and it ran great. My Jeeps biggest problem is always something vaccum related. Not too mention the previous owner lost/broke half of the switches etc. The vaccum diagram shows many parts I am missing and half of the lines are run wrong anyway. I think I am going to give it a whirl.

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                    • #11
                      I personally wouldn't do it especaially if your Jeep is your DD. Mine is still hooked to the air filter but I run a MC2100 so it doesn't fill up the air filter. If you don't have emissions testing I would look at vacuum diagrams and you can eliminate alot of the vacuum lines. Before I put in my HEI and MC2100 I revamped the PCV system and ripped out a bunch of vacuum lines and it definitely helped. Look into simplifying before you eliminate it completely.

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                      • #12
                        If I start getting booring, just stop reading

                        The PCV system is one of the contributing factors to modern (circa 1970 and up) engines lasting so much longer than older engines.

                        You will always have a certain ammount of blow by gasses that slip past the rings and into the crankcase. Without PCV this results in a number of little nasties. Three of the worst are as follows.

                        First: the crankcase presurizes and eventually the weakest seal (usually the rear main because it is the most difficult to change) will let loose and start leaking oil.

                        Second: These wonderfull gasses combine with the oil, heat and moisture that is in the crankcase and form a myriad of ACIDS that eat things like bearings, seals and even the engine block itself. The acids don't usually cause engine failure, that is left to number 3.

                        Third: all of the gasses that don't form Acids combine with the dirt and polutants in the oil and make sludge which can cause blocked oil passages and eventually engine failure.

                        PCV eliminates those problems by drawing the majority of the gasses back into the combustion chamber where they are eventually either burned or exhausted. At first is seems rather counterintuitive that you can solve a blow by problem by sucking the gasses back into the cylinder which is where they came fom in the first place, but time and experience has proven that PCV does result in a net reduction of the harmfull gasses and byproducts.

                        When you start getting oil in your air filter it is because the ammount of blowby has finally exceded the ammount of scavenging ability of the PCV system. Sometimes you can buy some time by using no smoke to thicken the oil and reduce the blowby or use mystery oil to clean the engine and possibly loosen the rings a bit and get them to seal again. I have also seen folks add a second PCV valve on V8 engines and others add multiple filters and oil traps to the fresh air side of the system in an attempt to reduce the ammount of oil that gets out of the crankcase.

                        Bottom line, if you are getting oil in your air filter, first make sure the PCV is connected and in good working order. If that does not help, change your breather element often and start saving for the inevitalbe.

                        One final note: Sometimes you will get a lot of blowby witha new engine untill the rings seat and the engine is properly broken-in, that is normal.

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                        • #13
                          readin my mind

                          I'm putting a rebuilt I-6 into my 86 CJ7 and was seriously thinking of pulling off all the extra crap. good to hear that it worked so well. With a rebuild I will keep the PCV but I think if I adjust the carb right, get my timming just right it will run better without too many vac lines. Got a photo?

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