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Thread: Engines....again

  1. #1
    Senior Member HillBillE's Avatar
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    Default Engines....again

    Hey guys, as some of you know, my freshly rebuilt 258 bit the dust, abou 300 miles into my Moab trip. I think I isolated the problem, it being the new HEI dizzy, and not the rebuild.

    Anyway, I'm having a hard time keeping engines in it, and would like something that can haul 75 on the road, and still idle all day on the trail/rocks.

    I really liked the JK with an auto that I rented in Moab, first time I really wheeled a slushbox, I've always driven manuals.

    So i'm kicking around the idea of a sbc, any of them, 305,307,327 or 350, mated to a 700r4 tranny thats adapted to my Dana 300 case.

    With the 700r4, I'd have (I believe) a lower 1st, and the overdrive I'd like on the HWY.

    The sbc will fit fine, I had one in there for a while. And being a '7, tranny length should be OK.

    So, anyone run something like this? Or have any suggestions for an engine/tranny combo thats similar?

    I plan on gathering parts during the summer, then doing the install over next winter, so I'm fishing for ideas, and any pro's or con's you may see in my idea. Thanks ! HB


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  2. #2
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    If you are trying to keep it jeep, throw a 4.0 in there. Otherwise, a SBC is the way to go in my opinion. They are relatively inexpensive, tons of aftermarket conversion stuff out there, you can get parts anywhere in the country, etc, blah, blah, blah. Unless you really need to do it cheap I would definately consider a modern Vortec engine 5.3, 5.7, or 6.0. These in stock form will give you more power then you will ever need for CJ7. If you like the auto, a built 700r4 is a good tranny, however it is long (especially for a CJ7) so check your lengths. There has also been some front drive shaft clearance issues on these. Another option is the Vortec 4.3 V6, which is another great proven engine(essentially a 5.7 minus 2 cylinders). It is shorter so you could move it forward on the frame to compensate for the tranny.

    All these swaps are well documented on the web. Take a look at Novak Adaptors for some info/research on what you want to do.

    I currently have a 305, TH350, NP205 in my Scrambler. It will be getting a TBI 350, Th350, D300 soon. My other rig is getting a 6.2 Diesel, NV4500, D300. I have a CJ7 that will probably get the 305 set up out of the Scrambler.

    Also look into the motor mounts from M.O.R.E. They are strong and very nice, well worth it, plus they off set the engine a little to compensate for front driveshaft clearances.

    Truck
    Quote Originally Posted by korisu56 View Post
    Im in no position to. Mine doesn't work.
    Quote Originally Posted by miljeep View Post
    Oh, thanks to Nate who stopped by tonight and helped a struggling old bald man pitch a tent.
    83 Scrambler, bought in 94...starting to rust away..."we can rebuild him" Now in pieces all over the garage
    82 Scrambler, bought in 05, chevy 305/TH350/NP205
    86 CUCV Maintanance truck w/12KW PTO driven generator & air compressor
    83 Scrambler-151/T176/D300...basically stock..possible restoration for DD duties

  3. #3
    Administrator Truck's Avatar
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    Sounds like from your other post you need a desposible engine . Like in racing, just have several sitting there ready to drop in when you blow the one in it.

    Truck
    Quote Originally Posted by korisu56 View Post
    Im in no position to. Mine doesn't work.
    Quote Originally Posted by miljeep View Post
    Oh, thanks to Nate who stopped by tonight and helped a struggling old bald man pitch a tent.
    83 Scrambler, bought in 94...starting to rust away..."we can rebuild him" Now in pieces all over the garage
    82 Scrambler, bought in 05, chevy 305/TH350/NP205
    86 CUCV Maintanance truck w/12KW PTO driven generator & air compressor
    83 Scrambler-151/T176/D300...basically stock..possible restoration for DD duties

  4. #4
    Senior Member HillBillE's Avatar
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    No kidding! I found the problem, a burnt exhuast valve. I think the culprit is the new HEI dizzy from 4WDH, made for the 258. I had a hell of a time getting the engine timed, and the vacuum/mechanica advance didn't seem quite right.

    The guys that rebuilt the motor think it was spark knock also. I brought the head into them today, and explained everything. Not sure what it'll cost, but Bob has always treated me good, so I'm not worried.

    I put about 800 miles on the rebuild, with little problems or spark knock, but tha was with an empty Jeep. Load it up, along with the adventure trailer, and she started pinging good on hills and in headwinds.
    Luckily it didn't score the cylinder bad, and I cuaght it before the damage was worse. Hope t have it runing this weekend. I have our club kick off run on the 10th, then we're hsting the annual open house at MN first OHV park. I'd really hate to have to drive my stock '93 ZJ!!

    Valve carnage:





    I thought a chunk broke off, but after the valve was out, it looks like someone took a plasma arc to it! Jeff from the engie shop, magnafluxed the valve seat, and it's not cracked. So I might get away with a new valve and a grind.


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


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