coolwind57 Posted May 30 Share Posted May 30 Well, it looks like I have my choice of which to use. I'd like your input. I did perform the internal shortening mod of my Renix aluminum cover years ago. But I picked up this stamped HO valve cover when I bought my 7120 head. Any benefit with going with the HO, with that very different "baffle" system inside? I do get annoying leaks with the non-screw in cap on the Renix that would probably go away with the design of the HO cap. Will the different baffle design help with excessive oils on the air filter element? I'll be running a Renix intake setup, so I'd need to adapt the larger lines from the HO but that seems easy to do. Any comments, guys? Link to comment Share on other sites More sharing options...
Salvagedcircuit Posted May 30 Share Posted May 30 Huh. I've never seen the inside of the HO version. It looks like some kind of sheet metal baffle insert that lines the entire top. Curious, are those plastic screw inserts along the perimeter of the HO valve cover? The HO one should weigh less if you are into weight reduction. I had to manually file my renix valve cover with a metal file and wet stone because the aluminum casting left a very poor edge quality from factory. The valve cover left a substantial indent in the nice $40 felpro reusable gasket. I had to grab another. I am curious too what other folks have to say! Link to comment Share on other sites More sharing options...
schardein Posted May 31 Share Posted May 31 I have the later metal valve cover on my 91XJ and 91MJ. But this was an aluminum HO cover to steel HO cover swap, so not the same thing you are asking about. I did it primarily because of the threaded oil fill cap. It's been a long time, I think the breather ports were in slightly different locations, so I had to modify the hoses, or maybe I got the hoses from the JY along with the cover. I didn't have issues with oil getting into the air cleaner before or after the swap, so can't speak to that. Link to comment Share on other sites More sharing options...
89 MJ Posted May 31 Share Posted May 31 I kept the aluminum Renix valve cover on mine when I installed the 96 block and head. I think it looks cooler and is more period correct. I’d sandblast it and clear coat it first though. Link to comment Share on other sites More sharing options...
coolwind57 Posted May 31 Author Share Posted May 31 5 hours ago, Salvagedcircuit said: Curious, are those plastic screw inserts along the perimeter of the HO valve cover? Yes, it looks like the plastic parts are keepers for the very-short metal tube that runs through the valve cover hole. That metal flares out to form a flat washer-like assembly that the valve cover bolts sit upon. 5 hours ago, Salvagedcircuit said: The HO one should weigh less if you are into weight reduction. No, I certainly wouldn't say that. I'd say they weight about the same....maybe the HO stamped one may actually have a couple more ounces to it actually. I hadn't weighed them, but only estimating by hand. I was surprised myself, thinking the stamped one would be lightweight, thin steel but it's quite thick and heavy. Link to comment Share on other sites More sharing options...
75sv1 Posted May 31 Share Posted May 31 Or.... There is the 91-95 HO from the XJ. A bit better than the RENIX. Has the baffle towers like the RENIX. Then there is the ZJ Aluminum Valve Cover. You might find than on an XJ once in a while. I have them on my '00 XJ and maybe my '98. They have the CCV grommets like the steel ones. Has the baffle towers like the RENIX and Aluminum HO. I did have a '95 HO on my '88 MJ. Suppose to control oil better than the RENIX. Also, did Cruiser's baffle tower mod. I think the steel one controls the oil the best. Then the ZJ's. I had to extend the CCV tube, when I had the Aluminum HO on my '88. Link to comment Share on other sites More sharing options...
schardein Posted May 31 Share Posted May 31 23 hours ago, Salvagedcircuit said: Curious, are those plastic screw inserts along the perimeter of the HO valve cover? These are the grommets. They are metal and rubber. Replacements usually come with replacement valve cover gaskets. The gaskets are the type that use a metal core with a silicone rubber coating that provides the seal. The grommets control how much the gasket is compressed when the bolts are tightened. Link to comment Share on other sites More sharing options...
Salvagedcircuit Posted May 31 Share Posted May 31 2 hours ago, schardein said: These are the grommets. They are metal and rubber. Replacements usually come with replacement valve cover gaskets. The gaskets are the type that use a metal core with a silicone rubber coating that provides the seal. The grommets control how much the gasket is compressed when the bolts are tightened. Very Cool! Thanks for the photo I was guessing since I never saw the stamped steel valve cover before. Link to comment Share on other sites More sharing options...
coolwind57 Posted May 31 Author Share Posted May 31 Funny, for the life I me I could not think of the word "grommet" on my post above. Getting old sucks. The mind is the second thing that goes.... Link to comment Share on other sites More sharing options...
Gojira94 Posted May 31 Share Posted May 31 3 hours ago, coolwind57 said: Getting old sucks. The mind is the second thing that goes.... Yeah, once your memory starts to go, you can forget it... "I heard there are 2 sure signs you're getting old- one, your memory starts to go, and the other... well, I forget." Interested to hear that my (donor engine) 93 YJ cover is different from the Renix cover. Hadn't thought of that. And I wonder what's different from the HO XJ aluminum and ZJ aluminum cover? And are they in any way different from the 91-95 YJ cover? Link to comment Share on other sites More sharing options...
schardein Posted May 31 Share Posted May 31 4 hours ago, Gojira94 said: Interested to hear that my (donor engine) 93 YJ cover is different from the Renix cover. Hadn't thought of that. And I wonder what's different from the HO XJ aluminum and ZJ aluminum cover? And are they in any way different from the 91-95 YJ cover? I don't think there is any difference between MJ, XJ, YJ, ZJ. I think it's strictly a matter of year differences. The parts manuals just show "Cover, cylinder head" for the 4.0 engine, not by model type. They list them with different part numbers. It looks like the breakdown is 87-90, then 91-92, then 93, then 94-95, then 96-? I don't have a 97-99 parts manual, but 2000 shows the same as 96, so I'm guessing 96-01, probably 96-06. Rockauto shows the same gasket for XJs 96-01, which also fits TJs 97-06. Link to comment Share on other sites More sharing options...
75sv1 Posted June 3 Share Posted June 3 I do not know what the YJ valve cover looks like. There is a difference between the 91-95 HO valve cover and the 93-96 ZJ valve cover. The HO has screw in to twist in CCV parts. The ZJ has CCV grommets like the latter metal VCs. The ZJ does have the oil baffle towers like the HO and RENIX. I do use the FEL-PRO rubber gaskets. About $35-50. Worth it though. Link to comment Share on other sites More sharing options...
Gojira94 Posted June 4 Share Posted June 4 (edited) This is my '93 YJ cover. I haven’t pulled it off yet, I’m OCD for cleaning before I do that, so I’ll have to add pics for what the baffles look like inside later. EDIT: that cable guide is backwards, it's just sitting there. It was missing and i grabbed one in not-so-good shape from a ZJ in my local yard for mockup purposes. Flipped around, it lines up fine with the 99-01 horseshoe intake arrangement/ alignment with HO throttle bodies, for what it's worth. Edited June 4 by Gojira94 Link to comment Share on other sites More sharing options...
75sv1 Posted June 4 Share Posted June 4 I'd say the YJ's is the same as the 91-95 HO. The twist ons are suppose to be better than the RENIX. Link to comment Share on other sites More sharing options...
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