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  • 258 valve cover

    I am looking to replace my plastic valve cover with an aluminum one. I see it requires drilling and tapping. I have not tapped anything before. Is this something a novice can do with a hand drill or do i need to take it to someone?

  • #2
    Yes it is, the tap you will be looking for is a bottoming tap( that wat it cuts threads all the wat down). the instructions will say what size drill bit and what tap size.
    All your doing with the drill is making the hole big enough for the bolts, not really drilling deeper. It's not that hard to do, if your paying attention you will feel when the dill bottoms.

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    • #3
      Use something that will fit in the holes such as a smaller drill bit and push it to the bottom. Mark the drill bit where is even with the top of the hole and transfer this measurement to the drill bit being used for enlarging the hole and mark it with a couple wraps of electrical tap. This will allow you to keep from overdrilling Make sure to keep the drill straight up and down the existing hole. When you start to tap the holes do not force the tap it will break. keep the tap straight up and down with the hole and once it starts to tap and cut threads work it backwards a quarter turn to for about every half turn to clean out the cutting tips and threads. Make sure to use tapping oil. If you are unsure try starting with a scrap peice of metal. If you have trouble getting the threads started with a bottom tap use a starter tap untill you start to cut threads and then switch to the bottom tap to finish the hole

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      • #4
        You make it sound easy. I thought I was drilling new holes in the head. Thanks

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        • #5
          one thing. dont tap with the drill. tap by hand, and if you feel the tap start to bind dont force it, if you break off a tap it usually sucks to get them out, take your time

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          • #6
            Tapping is way easy. Deceptively so. Like Catbacker said, go slow with a tap-handle (any good hardware store can set ya up with one for less than 10 bucks usually). Your sig says you have a '85? My '86 didn't need to be drilled, just tapped.

            I got the heavy finned 4.2 logo polished aluminum cover by Omix-Aida. I had to do much more work to the freeking cover than I did to the head. Had to wallow holes so the bolts would line up, the "polished" description was a bit optimistic, so I polished it myself too. I also sourced a new gasket as the supplied cork piece was junk. I went with a rubber gasket from NAPA.

            One bit of advice: the stocker has two bolts that are on cage/arms that straddle the valves and go thru the center of the stock cover. Once you take the stocke cover off, cover your valves! You will need to remove these center bolts: My directions said to saw them off, but I found mine easily fell out with a couple taps from a hammer. Note: they FELL out...right down inside the head. Luckily I got it fished out with a "magnet on a stick" tool and didn't have to remove the head!

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            • #7
              Good morning gents, here is my input on plastic to aluminum valve cover upgrade. Early ones like 1980 and1981 did not have holes in very front or back of valve cover. The rear one cannot in most cases be drilled in vehicle due to firewall clearence, and even tapping is tough. Most people just do not use these two, and if thats the choice made, I would add extra sealant at ends to ensure good seal if these are omited and let cure overnight to avoid wicking thru gasket.
              I prefer to have these drilled and tapped when possible but there are no holes to start with so it is more critical to use drillpress or mill. I use a shop vac hose beside drill bit when drilling on engine, to avoid chips in engine. I use tape on drill bit to limit depth of drilling, especially on drivers isde because drilling too deep will get waterjacket on one or two holes. If you do get water by accident you can drain down, clean with brake clean and thread lock or epoxy a setscrew in bottom.

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              • #8
                Gryphon, you had me convinced, I was was all in -picked out the Omix-ada 258 blue aluminum cover , ready to order... Then came Woody. Drilling into the water Jacket can't be a good thing. Is this a No Gain without pain kind of thing?

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                • #9
                  i would pull yours off and look, woody said the early ones didnt have the holes but if yours does then you should be ok, just take your time. Woody has a good idea with the shop vac to keep chips to a minnimum. good luck with what ever route you decide to go.

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                  • #10
                    Morning gents.
                    Hello njrob, did'nt mean to scare you. I used to run our tech dept and I only ever had one guy get water from drilling too deep. But I always try to explain and give all info that may pertain to the questions asked. I really is an easy job when time is taken to do it right.
                    Going to the aluminum cover is the best thing anyone can do to the 80 up 258's. You can install a new plastic cover every year for the rest of the Jeeps life, besides the aluminum ones look way cool when you open the hood!!

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                    • #11
                      I don't have it yet but I'm going to get the cover from Clifford Performance, I would recommend to check it out

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                      • #12
                        an alternative to changing valve covers
                        http://www.4wd.com/productdetails.as...39&partID=6779

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                        • #13
                          Niiiice. Im gonna need a new tool box for that.

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