Rebuilding a 4.0

    • Rebuilding a 4.0

      Maybe rebuilding isn’t the right word but I picked up a 4.0 out of a 95 yj. It will be replacing the 4.2 in my 88
      My 4.2 runs so I’m in no rush. My plan is to pull the head and see how it looks inside, reseal everything, clean it up and maybe paint it
      What I’m looking for is any recommendations on upgrades/improvements/preventive maintenance while I have the motor out and am in no rush. I’m looking online and I’m pretty much overwhelmed with the information and opinions that are available
      Any input will be much appreciated. Thanks
      Matt
    • my advice is to do nothing. Its basically an old tech forklift motor. It works great if u leave it alone. If u were gonna reman i would put a slight cam and mustang injectors in but thats because its fresh.
      '88 YJ with not much '88 left. :)
      Team Mall Crawler #609
      Werock Stock Class we-rock.cc
      Werock '06 - 2nd East Coast, 5th overall Werock '07 - 3rd East Coast Sponsored by: The Drive Shaft Shop driveshaftshop.com Delaware Jeep Assoc. delawareja.com
    • astape wrote:

      my advice is to do nothing. Its basically an old tech forklift motor. It works great if u leave it alone. If u were gonna reman i would put a slight cam and mustang injectors in but thats because its fresh.
      Do nothing? That sounds easy! I have no plans of going into the bottom end unless it’s necessary. So far the only thing I plan on doing is converting to an electric fan. That’s not necessarily a “the motors on a stand so take care of it now” type of thing though, I’ll probably do that during the engine swap
    • the header isnt a bad thing because the factory manifold is most likely cracked. Intake and tb spacer and exhaust just make noise, imho.

      Clean it and spray a few cans of mopar blue or on it and call it a day.

      Also be careful with electric fans. They dont pull near as much air as stock when daily driving. There are many different cfm rated fans that look the same . Generally the price reflects this.
      '88 YJ with not much '88 left. :)
      Team Mall Crawler #609
      Werock Stock Class we-rock.cc
      Werock '06 - 2nd East Coast, 5th overall Werock '07 - 3rd East Coast Sponsored by: The Drive Shaft Shop driveshaftshop.com Delaware Jeep Assoc. delawareja.com