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GM 153/181 4 cylinder swap. Tons of Q's

Discussion in 'Early CJ5 and CJ6 Tech' started by Mike C, Apr 4, 2007.

  1. Apr 4, 2007
    Mike C

    Mike C Member

    Austin, TX
    Joined:
    Feb 19, 2007
    Messages:
    743
    OK. Looks like this is the way to go to get a 4 speed pretty cheap and more power. I've searched the site and the web and have come up with some ?'s.

    I've found a 181 Mercruiser cheap and I already have an SM465 so D18 to 465 adapters should get me there. I may continue to look for a 420 as well. I'll sell my excellent running F134 and T90 to offset cost.

    Those of you who have done this swap, what did you do for intake/exhaust manifolds? Did you just run the crazy marine setup or switch to the industrial/automotive setup? Seems the marine setup would overheat the intake air.

    What about oil pans? Did you use the front sump pan or switch to a rear? Any good source for non-marine manifolds?

    Looks like 91 was the switch to one piece rear seal and the motor I have found is an 81 so should use internal balance small block flywheel which I have. Any advice before I part with my hard-earned cash?
     
  2. Apr 4, 2007
    Vhunter

    Vhunter Member

    Redding, California
    Joined:
    Jun 26, 2005
    Messages:
    262
    Howdy,

    Mine was an automotive engine so I used the stock intake and exhaust manifolds. And, yes you need to go to a rear sump pan to clear the front pumpkin. You mite have to fabricate your own intake and exhaust as the marine head is better and does not have Siamese ports like the automotive heads. I am using a Mallory electronic distributor and I believe the industrial motor may have an HEI distributor. I used stock Chevy bell housing and clutch parts, and it should bolt up to a SM465 like a factory install. I would go with the SM465 before I would use the SM420. Other than that, it fits in there real nice and clean and has more than ample power. Also, when people ask about my Jeep I just say, "Yeah, it’s just a four cylinder in there".
     
  3. Apr 4, 2007
    Mike C

    Mike C Member

    Austin, TX
    Joined:
    Feb 19, 2007
    Messages:
    743
    Cool. The Marine motor has electronic ignition, and it's water resistant. I'll run that. Any source for automotive parts? Clifford has a header but I can't find anybody with oil pans or intakes.

    I found some .pdf from GM on the Vortec 3000 marine and industrial engines. Looks like that might be a source for intake/exhaust manifolds?
     
  4. Apr 4, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Yeah, GM was advertising the 3000 as an industrial/marine engine until recently, like maybe 2 years ago or less (Hecho En Mexico). Intake/exhaust over the parts counter may still be available - I wonder if the forklifts got the marine head?
     
  5. Apr 4, 2007
    Vhunter

    Vhunter Member

    Redding, California
    Joined:
    Jun 26, 2005
    Messages:
    262
    As, stated above you mite get parts from the industrial side of GM (vortec 3000)for the rear sump pan and intake and exhaust manifolds. And, check eBay for pans and stuff, I bought an extra pan and a valve cover off of Ebay. They made a ton of these motors and parts should be out there. Als, check with a GM dealer to see if he can find the part # for the rear sump pan and pick-up tube for the oil pump. It takes a speacial main bearing bolt that has an extension of the threads on top of the bolt to mount the extesion tube too. Once you get this together it is a work horse, with five main bearings supporting only four pistons, you can turn 10,000 and not distroy it. Ask, the quarter midget racers, who used to use this motor.
     
  6. Apr 4, 2007
    Mike C

    Mike C Member

    Austin, TX
    Joined:
    Feb 19, 2007
    Messages:
    743
    I've got my eyes out. I've already found a Clifford aluminum intake. GM is still making the Vortec 3000 for boats and for industrial. Here is the link to the Industrial .pdf
    http://www.gm.com/automotive/gmpowertrain/engines/specialized/industrial/2007_industrial_engines.pdf

    And here is the marine: check out the available FI!
    http://www.gm.com/automotive/gmpowertrain/engines/specialized/marine/2007_3000_marine.pdf

    I've at least seen mention of rear sump conversion on some of my Google searches. If I can get the pickup, I'll fab my own pan if I have to. I would think some of the Nova places would have a line on those parts. Just might take a phone call.

    This is gonna' take awhile to get put together, but I'm pretty stoked on the whole project. I think I've got the outdrive sold already for what I'm paying for the whole shebang. I'll ditch the hull and build a motorcycle trailer from the boat trailer.
     
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