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Motor Decision

Discussion in 'Early CJ5 and CJ6 Tech' started by Phillip Sladek, Aug 22, 2019.

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  1. Aug 23, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    Before you pull run a compression test to see what the top end is like.

    drop the pan and pull the caps to see what the state of bearings & journals is.

    If you're lucky you might get away with a little polishing & a new bearing.
     
    47v6 likes this.
  2. Aug 23, 2019
    txtoller

    txtoller Member Sponsor 2019 Sponsor

    Weatherford, TX
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    I would go this rout, get it on the road, then look into a swap and get all your parts together.
     
  3. Aug 23, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    I did a compression test last night 105, 100, 100, 95, measured front of motor to back
     
  4. Aug 23, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    The 95 is a little concerning, the other 3 arn't terribly horrible, definitely down but not horrible.

    Did you squirt some oil in to see if it's the rings or possibly the valves?

    I'd still drop the pan to look at the lower end before going to the trouble of pulling the engine.
     
  5. Aug 23, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    no I did not add oil but should have now that you mentioned it. I will have to check that tonight
     
  6. Aug 23, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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  7. Sep 11, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    well I pulled the motor last night and started breaking it down. number 4 cyc looks like it broke a ring and chipped the top edge of piston which did a number on the top of piston.
    but the walls do not look scored at all. Greg's Engine & Machine in copley Ohio quoted me 300.00 to clean and bore the block. did not think that was a bad deal. so I am going to do a full rebuild on this engine and enjoy it for what it is. any advice or input is always welcome. i would post pictures but have not figured that out yet.
     
    Glenn, Hellion, Jrobz23 and 2 others like this.
  8. Sep 11, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    No wonder the bearings went south. I'm happy with F-heads, but they are not designed for high rpm. I consider 50mph the top end.
     
  9. Sep 11, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    well with the 31 inch tires and 3.73 gears at 60 mhp I am only running at 2800 rpm so i didn't think i was being to hard on the motor
     
  10. Sep 11, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    With that long stroke, piston velocity is really high. this puts a lot of stress on the rod bearings, and I'd guess it makes the rings wear faster.
     
  11. Sep 11, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

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    The proof is in the pudding, perhaps - busted rings and worn bearings.

    Not to criticize either the F-head or your way of using it. I myself learned this lesson the hard way as kid when I blew up the f-head in my dad's jeep, and I've never forgotten the look on his face.

    Early jeeps can suffer from the image of being a "sport" vehicle. In today's world of technology and the higher speeds of today's highways it is very easy to expect too much of a 1930's power plant. The f-head was ideally suited to crawling up a beach during an amphibious assault - but not so much for cruising interstate highways.

    I'm glad you will be rebuilding your F-head, and wish you many years great enjoyment with it.
     
  12. Sep 11, 2019
    Jrobz23

    Jrobz23 Member

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    Skinnier tires maybe? I know that helped mine with power.
     
  13. Sep 11, 2019
    Alan28

    Alan28 Well-Known Member Sponsor 2019 Sponsor

    Châtillon en...
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    I am happy with my 134 but around it is flat. Anyway I had to go up the local castel road, very hard, and in 2nd gear hop no problem full speed ...and noise.
    It is a good engine and you can repair it.
    then as said you can look for a good v6 and change and sell you 4 cyl.
     
  14. Sep 12, 2019
    Greevesman

    Greevesman Sponsor Sponsor

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    Yep! They are truly classic cars. And becoming more difficult to maintain the originality. I have a 65 with 134. An overdrive is a very interesting addition. 11" front drums so there is a chance of stopping. But you have to do what floats your boat.
     
  15. Sep 12, 2019
    Hellion

    Hellion Banned

    Eastern TN
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    Well when you do, load them all up. I wanted to see the number 4 piston especially.

    :pics:
     
  16. Sep 12, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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  17. Sep 12, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    this is what Cyl 3 and 4 looked liked
     
  18. Sep 12, 2019
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    I drove the snot out of my F4.
    T90, 5:38s, overdrive, 1100-15 flotation tires.
    Colorado and back twice.
    Probably put 20,000 miles over 9-10 years.
    The weekend before the V6 went in, went to Pismo Beach.
    Tried to blow it up in the big dunes; couldn't.
    It would easily turn over 4000 rpm in the dunes.
    F4 not as fragile as some would say.
    Sold it later for $100 in 1983.
     
  19. Sep 17, 2019
    Phillip Sladek

    Phillip Sladek New Member

    Mogadore ohio
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    Well I have the motor taken apart and started ordering parts. Will be dropping the block off at the shop next week to get cleaned and bored. anyone have a good suggestion for the rear seal at to which to buy and how to install so as it seal properly. That one that was on here leaked pretty bad.
     
  20. Sep 17, 2019
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

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    If it only leaked "pretty bad" then that's the good type. :D
     
    Twin2 likes this.

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