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4.0 head swap. What Carb, Vac advance???, Temp sending unit??

Discussion in 'Intermediate CJ-5/6/7/8' started by CJ-ING-RJ, Mar 22, 2012.

  1. Mar 22, 2012
    CJ-ING-RJ

    CJ-ING-RJ Member

    Iowa
    Joined:
    Jul 29, 2010
    Messages:
    146
    Here's the specs. 74 CJ5 I6 258. Original block was cracked. Got a donor 81 complete. Used the 81 block bored .030 over, crank .020 under and mains .010 under. R&R master rebuild kit. Torq camshaft (1 step up) and lifters. 4.0 head Casting # 0630 modded for a 258 w/3 angle grind. 97 Grand Cherokee valve cover and exhaust manifold. 81 2v intake and all the 81 tin work. All new (exterior) Stainless Steal hardware. oh and Dupli color engine enamel paint.... I think that's it....:? probably forgetting something.

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    Well guy the rebuild has been coming along great!! About ready to drop her back into the engine bay.... So now I'm ready to spend a few more $$$$$$. I'm wondering what Carb you guys would recommend? I'm thinking from what I read, I want to look for around a 400CFM. I know less than nothing about Carbs so I want to keep it simple. I don't plan on running anymore vacuum lines than necessary. I want to keep this as SIMPLE AS POSSIBLE.. Also I need your advice on where to locate my Temp sending unit. My original 74 (and 81 donor) had it on the head in the front. Well the new 4.0 head (0630 casting #) does not have a spot for it so????? I was thinking of putting it in the rear 3/8" opening on the intake manifold where it goes into the water jacket. Would this work? here's a pic of the intake.
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    Oh also looking for a new vacuum advance (I think that's what it's called) goes on the intake just below the carb..... Any suggestions or would one off the 74 or 81 work after getting them cleaned up, there pretty bad..
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    Thanks in advance!!!! RJ
     
  2. Mar 25, 2012
    CJ-ING-RJ

    CJ-ING-RJ Member

    Iowa
    Joined:
    Jul 29, 2010
    Messages:
    146
    What did I get black listed???? Really no one has a opinion or thoughts???? Please Help pretty please....
     
  3. Mar 25, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    If you want a tried-and-true option, pick the 32/36 DGEV Weber, or the 38 DGES, or a Motorcraft 2100 or 2150. Lots and lots about this topic on the web if you search.

    Or you can go throttle-body fuel injection ... lots of options and coverage there too.

    Your question about "vacuum advance" - do you mean EGR? Read the TSM for more about the EGR.
     
  4. Mar 25, 2012
    pathkiller

    pathkiller Member

    Lorton, VA
    Joined:
    Apr 17, 2005
    Messages:
    878
    I'm using a Motorcraft 2100, same carb I was using on the 258 before the rebuild and 4.0L head swap. There are countless write-ups about it on the web, so I wont' detail it here. Just google MC2100 and you'll see what I mean.

    The Weber seems to work okay for some, not as well for others. They can be tricky to tune, so if you don't know anything about carbs, probably not a good choice. They're pretty expensive, too. For the price I'd rather put the money toward EFI.

    You won't be able to use the stock EGR setup (the thing just under the carb) with that header. The stock setup used a pipe that connected from the exhaust manifold to the intake manifold. WIth the header there is nowhere to pull exhaust gas from (the EG of EGR is exhaust gas). So the best bet is to just make a plate to block that off and forget about EGR.

    Are you sure your head isn't tapped for a temp sender? I can see the hole plainly in one of your pics. It's on the manifold side of the engine, just next to the last head bolt on the back. See that hole pointing straight up? Just above the exhaust manifold bolt on the back? That's the temp sender. If you don't plug that hole you'll have coolant shooting out of it as soon as you start to fill up the radiator.

    The only required vacuum lines are for the distributor (vacuum advance), which runs from the base of the carburetor, and for the crankcase ventilation system. You'll have to put a breather vent in the front hole of your valve cover and a vacuum line to the rear hole. Best bet is to use the stock 4.0L grommets and connectors. I connected my front port to the bottom of the air cleaner so it's pulling fresh filtered air, and the rear to the PCV vaccum port on the bottom of the carb. If you have power brakes you will also need a vacuum line to the brake booster. That's all.
     
  5. Mar 25, 2012
    chsullivan

    chsullivan Member

    Houston TX
    Joined:
    Mar 27, 2010
    Messages:
    115
    Nice job, did you make your own washers for the exhaust/intake I'm looking at doing this conversion later own and currently have the offenhauser intake with a holly 390 that was done by the first owner. Which for off road did not work it would flood going down steep inclines and would starve going up, I spent every bit of 3 hours adjusting floats and had enough and parked my rig for the rest of the weekend and had to ride with a friend. So the Holley is going for sale and I have the Howell fuel injection on the way, It cost a bit more and I know I probably could have got a set up from a junkyard for half the cost but I'm not good at striping harnesses and all that jazz and don't have access to junkyards you can walk around in here and they want to charge you out the rear for there used stuff that they pull and bring to you (good ole houston). So not sure how you plan on using your ride street only or what but from my experience if you offload at all save and get injection just my 2 cents.
     
  6. Mar 25, 2012
    CJ-ING-RJ

    CJ-ING-RJ Member

    Iowa
    Joined:
    Jul 29, 2010
    Messages:
    146
    Ya I ended up cutting 8 pieces of stainless steel at work in a triangle shape 1 1/4". It seems to be working so far but well see when I get her fired up.

    Thanks for the kick in the melon Pathkiller. I don't know about others, but I definitely have my brain fart moments and sometimes it takes a reminder to figure it out. For some reason I kept thinking the holes for the alignment dowels were threaded. My head got shipped to me with out any dowels in it.
    AHhaha Just found that little hole late last night when buttoning up the valve cover was wondering what it was for:beer:

    Here's a pick of the progress... and NO I didn't make that battery tray that is PO.....
    [​IMG]
     
  7. Apr 1, 2012
    chsullivan

    chsullivan Member

    Houston TX
    Joined:
    Mar 27, 2010
    Messages:
    115
    So what's the status, what carb/injection, is it running or progress have you made?
     
  8. Apr 5, 2012
    CJ-ING-RJ

    CJ-ING-RJ Member

    Iowa
    Joined:
    Jul 29, 2010
    Messages:
    146
    Well progress has been made!!! It has completely blown my budget doing so but hopefully by the end of the weekend it will get the road test... due to lack of homework on my part I ended up with a T case/transmission swap also. The old girl now has a T176 and Dana 300 in her.... Hopefully my new drive shafts will be done tomorrow so all that is left is some fine tunning and exhaust. Haha ya right. I did the cam break in Last weekend and she roared like a lion.:).. I ended up going with the Weber 38/38.

    Here is the laundry list of stuff done..

    81 block bored 30 over crank and rods ground down. R&R complete enging rebuild kit. 4.0 head 81 intake shaved to to fit. 97 Cherokee valve cover and exhaust manifold. New water pump alternator belts hoses spark plugs starter oil pressure sending unit temp sending unit. New to me T176 and Dana 300. Custom (shorten rear lengthen front) drive shafts. Oh and I went with the Weber 38/38 2bl carburetor. Man I really hope that's it but I'm sure I'm forgetting something.. all and all a good experience for my first rebuild but I'm ready to have her on The road. I'll try to get some pic up here in The next few days.

    By the way anyone know a good spot to pick up a nos oil pressure gauge or a decent replacement for the 74 model year..
     
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