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Fuel Pump Spacer

Discussion in 'Early CJ-5 and CJ-6 Tech' started by spiderman, Jun 12, 2019.

  1. Jun 12, 2019
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
    Messages:
    69
    Going to the experts , once again. I already did an extensive topic search , and answers were
    all over the board . I am taking out a 53 M38A1 engine , F-head , and replacing with 55 CJ5
    engine . I had replaced double acting fuel pump with an Airtex 572 single acting pump , after
    removing thick spacer , 0n 53 , mounting pump directly to block . 55 engine needs pump . When I
    pulled double acting pump off of 55 , a thin spacer , about 1/8 " thick was there . The million dollar question
    is , leave the thin spacer , or remove it to put on the 572 pump ? Thanks
     
  2. Jun 12, 2019
    scoutpilot

    scoutpilot Member Sponsor 2019 Sponsor

    Asheboro, NC
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    What are you doing for a PCV system?
     
  3. Jun 12, 2019
    53A1

    53A1 Member

    Kern Co. Ca.
    Joined:
    Jun 17, 2008
    Messages:
    255
    I would go by the length of the fuel pump lever. If you pulled the original military pump that was working I would measure the arm and see if they match. As a side note, I recall the engine mount plates differ between the A1 and the CJ5. The A1 engine mount plate has a a square recess the clear the military pump.
     
  4. Jun 12, 2019
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
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    69
    The 53 was never set up properly for PCV . The 55 has the bell connector , and valve coming off of it that I was going to use ,
    coming off the side valve cover . Both engines have the square cutout in the mount plate .
     
  5. Jun 12, 2019
    scoutpilot

    scoutpilot Member Sponsor 2019 Sponsor

    Asheboro, NC
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  6. Jun 12, 2019
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
    Messages:
    69
    Scoutpilot, I was not aware of that . Looks like I need to use a dual acting pump , even without having vacuum wipers . Went right over my head why it was teed off to the fuel pump . This hunk of iron is older than me, and I'm still learning from it , and this group . Thanks
     
    scoutpilot likes this.
  7. Jun 13, 2019
    53A1

    53A1 Member

    Kern Co. Ca.
    Joined:
    Jun 17, 2008
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    255
    That's the first time I've heard that you need the extra vacuum for the PCV. I've always heard it's only needed for additional vacuum to run the wiper motors. I've been running a F134 with no vacuum assist and no wiper motors and I haven't observed a problem. I may need to check into that this weekend. My understanding is at idle the valve will get pulled closed due to high vacuum. At higher RPMs the valve should open and you should see vacuum after the PCV. You want vacuum on the crankcase at high RPM to pull the blow-by.

    But as I recall the cutouts are different. The stock military pump has a larger upper housing. It won't matter in your case if you don't intend on using the pump off the A1.
     
    Last edited: Jun 13, 2019
  8. Jun 13, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    Aug 3, 2003
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    PCV systems as a concept were born from the need to waterproof the F-head engines in military jeeps for deep-water fording.
     
  9. Jun 14, 2019 at 10:27 AM
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
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    69
    I have a dual acting pump that I got from quarter ton . it appears to not be any bigger than the AC pump
    that came out .
     
  10. Jun 14, 2019 at 11:12 AM
    53A1

    53A1 Member

    Kern Co. Ca.
    Joined:
    Jun 17, 2008
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    I know there is a difference but I just can't remember exactly. I found this m38a1 engine swap - G503 Military Vehicle Message Forums

    Read the whole thread. It's very good. Just don't want you to run into problems.
     
  11. Jun 14, 2019 at 12:43 PM
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
    Messages:
    69
    Thanks, I will read it in full . I'm 63 , and this is first time I have ever changed an engine . Really don't need any
    additional problems , and that's why I appreciate all the help I have been getting from you guys . BTW , I bought this as an
    assembly; engine , transmission , and transfer case . Will be installing as a unit after splitting apart to put new clutch in .
     
  12. Jun 14, 2019 at 3:32 PM
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
    Messages:
    69
    This is a true frankenjeep . All indications tell me I have a 53 M38A1 tub , and powertrain set into a 59 CJ5 frame . I can go over
    particulars just to verify . Battery box on r.h. frame rail , no reverse shackles , engine had most of fording system removed . Large fuel
    fill with large tank capacity . No tailgate , CJ grill in it . How can I post pics ?
     
  13. Jun 14, 2019 at 3:35 PM
    53A1

    53A1 Member

    Kern Co. Ca.
    Joined:
    Jun 17, 2008
    Messages:
    255
    I'm getting up there in age also. I re-read the post and the consensus was the only difference is the generator mounting bushing on the plate so you should be fine.
     
  14. Jun 14, 2019 at 3:41 PM
    53A1

    53A1 Member

    Kern Co. Ca.
    Joined:
    Jun 17, 2008
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    This is very common. After reading the post I linked to, the front plate difference is N/A. I think your fine. FYI, the A1 frame will have a machine gun mount plate on top of the rear cross member and boxed front frame horns. The A1 tub will have a power receptacle on the side and sunken front lights.

    If you still want to post pics, just select upload file on your next reply.
     
  15. Jun 19, 2019 at 6:57 AM
    spiderman

    spiderman Member

    Putnam , Ct.
    Joined:
    Dec 15, 2014
    Messages:
    69
    It turns out after further investigation that front plate on the donor engine is bent up , so we're gonna use the one out of the original engine . That will accommodate my 12v alternator conversion better anyway . I'm still interested in whatever light you guys might shed on the pcv setup . I do have the dual acting pump on already , so I can plumb it to pc v , or bypass it . Thanks
     

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