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Thread: SB Chevy Valves in 4.0 Head, Roller Rockers, Wiring Harness

  1. #1
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    Default SB Chevy Valves in 4.0 Head, Roller Rockers, Wiring Harness

    I was wondering if anyone has done this. Any pit falls? Valve shrouding, springs etc. So far I am thinking Manley SBC valves, BBC springs and keepers and ream out the valve guides to fit the valves.
    I was also wondering if anyone looked into adapting the Ford Pedistal type roller rockers onto the 4.0L head. Same ratio, but I haven't heard any talk of this. I looked into other roller rockers, but very expensive or they don't have a supplier at the moment. Or possibly Crower (rail type).
    I am in the process of swapping in a 2003 4.0 out of a Grand Cherokee into an 88 Comanche. I am thinking of putting in the wiring and emmisions from a 93-95 Cherokee. Do the wiring harnesses differ between the manuals, automatics and 2WD, 4WD.
    Tom

  2. #2
    Bad Ass XJ
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    You can put big block Chevy rockers on your 4.0L head. http://members.tripod.com/~Mojo_Page/Rokr1.htm

    The general opinion is that roller rockers in the stock ratio dont offer enough increased power for the cost.

    AARON
    91 Comanche Truggy...Built for fun on 35s

  3. #3
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    I've seen that website before. I think thats a 4.2 head and motor. There's a lot of machining involved. I could do it if I had access to a Bridgeport. (I do but not with something that involved.) At a certain point a person has to ask wheather the MOPAR or HesCo roller rockers are the cheaper way to go. I think Crowers are $316,but a rail type. Some have mentioned Harland Sharp. They don't specifically list a set for the 4.0, but have 'twin' adjustable pedistal types. Cliford is looking for a new supplier, so no idea on cost of them. I still might look into the Ford pedistal. Usually the are about $250 or less. From what I read there might be geometry issues, but that wouldn't be critical till about 6K RPM. I doubt thats much of a concern on a street motor.
    Tom

  4. #4
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    What's the rocker studs on the 4.0 heads, are they 3/8"?
    If so I think a common 1.6:1 RR for an AMC V8 could work assuming the stud to valve distance is the same.

  5. #5
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    yes it can be done.

    chevy 1.94/1.50 valves (11/32) fit if you recut the seats and ream out the guides to 11/32. Get valves with one grove for the keeper if you can. That way the valve seals dont hit the second grove.

    SBC valve seals work

    if you go 2.02/1.60 you may have to unshroud the valves and port match. (just more work)

    ford 302 springs (Crane lists the same for the 242) and 289 retainers. 289 have a .015 offset but 302 will work.

    cut spring seat .050 for correct install hight of springs (1.7 i think it was?)

    .050 offset keepers

    good idea to cut the top of the guided down but it depends on your cam. Crane Cam 901 will be close but it works.


    this is what my friend and i did for the head on his stroker. Chevy stainless steel valves are $8 compared to $15 for stock jeep ones. his guides were worn out to so instead of putting guided in the head we just cut them to fit chevy valves.
    There were a few other valve/ retainer combos we came up with but we used parts that we had on hand and could measure.
    1989 MJ 2WD short bed, 4.7L stroker, Ported 7120 head w/ SBC valve springs, AX-15, Luk Pro Gold clutch, new chunk of unibody welded in, new floors, 97+ front clip half installed, 1991 wiring harness.

    1991 Miata, ported 14b turbo, 26"x7" intercooler, ebay manifold and downpipe, LC-1 wideband, Megasquirt, 550cc injectors, 2.5 exhaust, AGX shocks, RB springs, 11th place 2008 GRM Challange, 13.9@107mph 1/4 mile Build pics!

  6. #6
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    2door94 thanks for the info. As far as putting 3/8 rocker studs and bolting up a 1.6 ratio roller rocker, you would have to fing guide plates that have the width to keep the push rods in place, so the roller rockers keep on the valve. Crower does away with this with a rail type roller rocker. I think Ford used this on mid 70's 351Ws and 351Ms. Still, I think the simplest route would be Pedistal type rockers. I will check into it further.
    Tom

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