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  • Shimming a Mitsubishi "cams"

    It's a Mitsubishi Pajero import 2.8 Diesel SUV

    Mate of mine cooked the head ...coolant leak.

    head is trashed numerous cracks .

    he says he can get a new "bare" head for it .....no valves or cam, cheap

    so he has to swap the valves and camshaft over .

    it will require re-shimming

    i believe they are solid lifters with shims on top ...the shims appear be "contained" on top of the lifters

    he is worried about the cost and availability of the shims.

    looks like to me ..that you could grind the underneath of the shims that are high on my surface grinder or grind the ends of the valves ....and insert in shim metal below the shims that are low

    rather than buying new ones.

    i know this doesn't sound conventional ..
    will it work..........

    all the best.markj

  • #2
    The first thing to do is find out how big the problem is. You may be able to get a lot of the clearances within specs just by swapping around the shims and valves you have. Then deal with the others as you have said. That seems like a reasonable approach.
    Any products mentioned in my posts have been endorsed by their manufacturer.

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    • #3
      That's called Shim and Bucket cam clearance adjustment.

      Before you go to grinding any shims or valve stems, why not try asembling it with the shims you have from the prior head? Once you have a a chart showing the clearance on each valve with existing shim, you can calculate what shims you need.

      They are not all that expensive from the dealer and factory shims would certainly last longer. Grinding would be a last resort.

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      • #4
        yes the plan was to swap them about ..i didn't say .

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        • #5
          I'm sure there are a variety of things that can be made to work. A friend of mine worked on a Jaguar engine which also uses adjustment shims under the cam followers to set clearance. One spot he pulled apart didn't have the customary round factory shim, but a squarish one with rounded off corners so it would fit the space in the spring retainer. Looking very carefully one could still make out the faint trace of the name "Nicholson" on the shim. I never knew they once supplied Jag shims.
          .
          "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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          • #6
            I wrote this spreadsheet (with a bit of help) some time ago to ease the pain of shim adjustment.

            [/quote]
            Peter - novice home machinist, modern motorcycle enthusiast.

            Denford Viceroy 280 Synchro (11 x 24)
            Herbert 0V adapted to R8 by 'Sir John'.
            Monarch 10EE 1942

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            • #7
              looks like you need the full excel program for it to work and not just the viewer that ive just downloaded

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              • #8
                Yep, grinding them would be a definite disaster. These shims have to fit fairly close in the top of the tappets, but they also have to be near perfectly parallel top & bottom. No doubt, a Mitsu dealer would probably have them, especially if they do any diesel work.

                Bucket tappets with machined shims isn't unusual. A lot of European cars use this system for valve lash adjustment.

                The old Cogsworth Vega engines also used shims like this.(I know, I had one that had to have the cylinder head replaced, when I worked for a Chevy dealer) Fiat, Ferrari, Mercedes...I'm not sure, but I think the old Jaguar inline six-cylinder had bucket tappets, too. Quite a few motorcycles use them too.
                No good deed goes unpunished.

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                • #9
                  I have a surface grinder !

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                  • #10
                    Some things to think about

                    One problem that can come up when you grind shims is warpage if you don't control heat perfectly. And if they become magnetized they can stick to the cam and ride out of the bucket. (that is a problem with shim over bucket)

                    There are 2 types. Shim under bucket and shim over bucket. They aren't all that expensive and are far cheaper than tearing the head out again because you didn't get it right the first time.

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                    • #11
                      One thing that I forgot to mention was the fact that the shims, regardless of weather they're over the tappet or under the tappet, is that the shims are hardened and ground. A surface grinder might go through the hard facing, then you'd have problems.

                      I did get an old Jaguar 2.4L Sedan in the shop once. The top end was making a horrible amount of noise. Close inspection revealed that the previous owner had "touched up" the valves on the old 2.4 and didn't have the correct shims to fit under the tappets....so, he made some out of "hardware store" washers, and sized them with a large file. Needless to say, the engine didn't like it's homemade tappet shims...at all. We gave the customer a quote for pulling the old Jag out of the "shadetree's' clutches (and put it right.)

                      After he stopped hyperventilating, and calmed down, I offered to perform an engine "transplant" for almost half of the price.

                      The Jag left our shop with a used, junkyard, 289 Ford V-8 and a C-4 three-speed automatic. (I did have to cut the front springs two coils to get it to ride level) After driving it, the customer came back to express his satisfaction by taking the whole crew out to dinner. Last I heard, he was still driving his 289 Jag Sedan.
                      No good deed goes unpunished.

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                      • #12
                        As has been mentioned there are over bucket shims that ride between the cam and sit in a pocket in the cam follower, and then there are under the bucket shims that fit between the cam follower and the valve.

                        The under the bucket shims although fool proof, because they are captive, are a royal pain in the ass to change because the cam has to be lifted to change them.

                        The shims that sit on top of the bucket are easier to service, but they can spit out at high rpm. This usually only happens at or near valve float rpm, so not that big of a problem.

                        However, when you combine multiple shims on top of a cam follower you do set yourself up for shim spitting.
                        Good insurance to just bite the bullet and get the correct shims.
                        Home, down in the valley behind the Red Angus
                        Bad Decisions Make Good Stories​

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                        • #13
                          Originally posted by aboard_epsilon
                          looks like you need the full excel program for it to work and not just the viewer that ive just downloaded
                          You can download Spread32 which is a mini Excel. It will process this .xls file.

                          http://www.321download.com/LastFreeware/page14.html

                          Gene

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                          • #14
                            Originally posted by saltmine
                            Yep, grinding them would be a definite disaster.
                            This is wrong, you clearly have little experience with import vehicles. The machine shop that does all my head work grinds shims all the time. They have a machine specifically designed for grinding shims similar to this one,
                            http://www.piccinotti.it/htm/e_ml100.htm
                            It leaves a mirror finish.

                            The bucket and shim valve train is a superior system to a rocker arm system. It is much more efficient and puts vertical pressure on the valve,
                            unlike a rocker arm that pushes the valve tip from side to side causing guide wear.
                            Mark Hockett

                            Comment


                            • #15
                              Originally posted by Mark Hockett
                              This is wrong, you clearly have little experience with import vehicles. The machine shop that does all my head work grinds shims all the time. They have a machine specifically designed for grinding shims similar to this one,
                              http://www.piccinotti.it/htm/e_ml100.htm
                              It leaves a mirror finish.

                              The bucket and shim valve train is a superior system to a rocker arm system. It is much more efficient and puts vertical pressure on the valve,
                              unlike a rocker arm that pushes the valve tip from side to side causing guide wear.

                              So, there's no problem with ever grinding though the hardened area. That's interesting.

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