258 valve cover on a 4.0 0331 head with roller rockers

[akadeutsch]

First, I like the look of the 258 valve cover more than I like my stock 4.0 valve cover so I will probably use the 258 valve cover whether I get roller rockers or not....But, If I do want to run roller rockers I have heard that they will contact the valve cover on the stock 4.0. If I use a 258 valve cover on my 0331 head will the Roller Rockers still hit the Valve Cover? In other words, is the 258 Valve cover taller than the stock 4.0's?

[jsawduste]

I could be wrong but I do not think the 258 and the 4.0 VC`s are interchangeable. Other thing to consider is the later model 0331 VC has a much improved baffling setup then the 258 or the 7120 4.0 heads.

Hesco spacer is how I set them up with a 7120 gasket on the bottom and a 0331 gasket on the top of the spacer. To help keep things aligned stainless steel studs with a dab of red loc-tite instead of the bolts.

The other nice thing about the later VC is the sleeves they use . This prevents over tightening.

[akadeutsch]

The bolt pattern seems to line up.

[SilverXJ]

Even if the valve cover bolts line up I wouldn't use it. The early 258 cover has 7 bolts. The 4.0L cover has 15 bolts. Better sealing. However, the last years of the 4.2L did have the 4.0L bolt pattern... but they look very much like the 4.0L cast aluminum cover. I also don't believe it to be any taller.

I believe the cover that jsawduste is referring to is the 96+(iirc) stamped steel cover with a baffle running the entire length.

Depending on which rockers you go with you may need the Hesco spacers.

[akadeutsch]

Thanks guys. I did not really consider the technology involved in the design of the VC. I think it has a pretty straight forward job and as long as it does not leak I do not see any advantage to baffles. What benefits do these baffles offer? As I understand the oil flow, oil flows up the push rods through the rockers and back down through the oil passage ways in the head. The valve cover has the simple job of retaining said oil as it runs from the push rods down through the block. Im going to run the 258 valve cover because I can't find my 4.0 VC and ill keep this updated as to the effects on the engine. If I ever get it back together.

[SilverXJ]

Thanks guys. I did not really consider the technology involved in the design of the VC. I think it has a pretty straight forward job and as long as it does not leak I do not see any advantage to baffles. What benefits do these baffles offer? As I understand the oil flow, oil flows up the push rods through the rockers and back down through the oil passage ways in the head. The valve cover has the simple job of retaining said oil as it runs from the push rods down through the block. Im going to run the 258 valve cover because I can't find my 4.0 VC and ill keep this updated as to the effects on the engine. If I ever get it back together.

Your description of the oil flow through the push rods up to the valve train is a bit simplified. It just doesn't flow. It sprays. Take the valve cover off and bring the engine rpm up.... oil will be every where in short order. This is where the baffles come in. They block all that oil from flooding the CCV system and drawing oil into your intake manifold and filter box.

[akadeutsch]

Bump. The 258 valve cover cracked when I torqued it down (it did not fit). so I will be finding a new VC

[bbarrett]

Bump. The 258 valve cover cracked when I torqued it down (it did not fit). so I will be finding a new VC

The 258 vc has a ridge around the bottom to keep the gasket in line. It will not fit the 4.0 head UNLESS you remove this ridge! I run the 258 vc on my 4.0 head!

[amceaglesx4]

All I know is I tried putting a renix vc onmy 7120. It wasnt having it. I hate the newer vc's with the rubber washers. I even shaved the vent tubes down and still didnt fit right. It looked sharp painted black with the top lines wizzied down to show the aluminum. Oh well steel one went back on. Who thought of the shitty plastic cover ? That was a stupid idea !!!