I recently bought and installd a replacement for the plastic fantastic valve cover on my '84 CJ w/258cid i6. The plastic cover was leaking so bad I thought I had a blown rear crank seal. Now its dry as a babies butt. BUT I thought some of you might like to know what I found out, and maybe save yourself some time. So:
The cover I bought is polished aluminum (OMIX-ADA#83501398K-AL). It is for the '81-'86 4.2 engine ONLY, and was reasonably priced at about $60. It came with hardware and a thick cork gasket. The instructions are pretty much correct except for.... I found the tolerences to be a bit tight. My head had 1/4-20 as well as 5/16-18 bolts, and two of the bolt holes were not tapped at all, since they used a bridge type clamp along the driver-side of the head to hold the old valve cover down. I used transfer punches to mark the holes through the new cover, then drilled them for a 5/16 tap. I used a standard tap first, then chased it with a bottoming tap. (So I didn't have to drill so far) I glued the gasket to the cover but didn't let it set up before I tried it out. Because the holes are so tight there isn't much wiggle room and my first try leaked. This is what I did;
I ran heli-coils into all the 5/16 holes and made them 1/4-20s. Then I used pan-head screws instead of those allen head bolts packaged with the cover. THE MOST IMPORTANT THING was that on my second attempt I glued (RTV) the gasket to the cover and let cure for 24 hours before I re-mounted the cover. The reason is that there are areas where the gasket has to mate with the head along a very narrow seating surface. You want to make sure the gasket dosn't shift during installation and the only way is to glue it down good to the cover. I opted to go with the pan screws because I can take off the cover with a phillips screw driver instead of needing 2 sizes of allen wrenches.
I think the upgrade is well worth the effort. It looks great and it dosn't leak.
Hope this helps.
The cover I bought is polished aluminum (OMIX-ADA#83501398K-AL). It is for the '81-'86 4.2 engine ONLY, and was reasonably priced at about $60. It came with hardware and a thick cork gasket. The instructions are pretty much correct except for.... I found the tolerences to be a bit tight. My head had 1/4-20 as well as 5/16-18 bolts, and two of the bolt holes were not tapped at all, since they used a bridge type clamp along the driver-side of the head to hold the old valve cover down. I used transfer punches to mark the holes through the new cover, then drilled them for a 5/16 tap. I used a standard tap first, then chased it with a bottoming tap. (So I didn't have to drill so far) I glued the gasket to the cover but didn't let it set up before I tried it out. Because the holes are so tight there isn't much wiggle room and my first try leaked. This is what I did;
I ran heli-coils into all the 5/16 holes and made them 1/4-20s. Then I used pan-head screws instead of those allen head bolts packaged with the cover. THE MOST IMPORTANT THING was that on my second attempt I glued (RTV) the gasket to the cover and let cure for 24 hours before I re-mounted the cover. The reason is that there are areas where the gasket has to mate with the head along a very narrow seating surface. You want to make sure the gasket dosn't shift during installation and the only way is to glue it down good to the cover. I opted to go with the pan screws because I can take off the cover with a phillips screw driver instead of needing 2 sizes of allen wrenches.
I think the upgrade is well worth the effort. It looks great and it dosn't leak.
Hope this helps.
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