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  •  » Ford has me a little irritated (piston ring thickness)

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    10/01/2020 9:27 PM  #1

    Daze
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    From: Kalispell MT
    Registered: 1/24/2013
    Posts: 1,130

    Ford has me a little irritated (piston ring thickness)

    As I have talked about in a previous posts I am in the middle of s "redneck rebuild" of a 351W.  In other words I am re-ringing and resealing the motor but not having any work done at the machine shop other than they hot tanked the block, magnafluxied the block and honed the cylinders.  Machine shop said block looks good and is a good candidate for a re ring.  Anyway I ordered a gasket kit, new bearings and a set of piston rings.  Today I installed the cam, crank, and timing set.  I then turned to the pistons.  I removed the OEM rings and tried to install the new rings but the new rings are too thick, all three of them.  Turns out Ford used two different thickness, a 5/64" and 3/16" set and a 1.5mm and 4mm set.  I ordered the 5/64" set because it was listed as the correct part for my application.  Turns out I need the mm set.  Not happy!!

    If it isn't broken...modify it anyway! http://www.DazeCars.com https://galaxieforum.boardhost.com
     

    10/02/2020 6:03 AM  #2

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,502

    Re: Ford has me a little irritated (piston ring thickness)

    Welcome to working on Fords

    What should be and what is are often two different things.  My truck for example should have been a 20mm head dowel pin engine.  I bought the 20mm gaskets before I pulled the heads.  Wrong, dead wrong, it was an 18mm despite being out of the production range where ford was using 18mm heads.  I learned my lesson, when there are two possibilities either wait to take it apart and check, or buy both and return the one that isn't right. 

     

    10/02/2020 10:40 AM  #3

    Nos681
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    From: Atlantic Mine, Michigan
    Registered: 7/14/2016
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    Re: Ford has me a little irritated (piston ring thickness)

    Is there a way to tell what size rings are prior to disassembly?

     

    10/02/2020 10:50 AM  #4

    Daze
    Forum Moderator & Bash host 2011

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    From: Kalispell MT
    Registered: 1/24/2013
    Posts: 1,130

    Re: Ford has me a little irritated (piston ring thickness)

    Nope. In theory you could go by year. Ford supposedly made the switch in 96 but both sizes are listed for all the f4 blocks. Also my engine came from a 95 but I think the engine was replaced. At least that is what the previous owners son-in-law thought. So unless you know the entire vehicle history you can’t even guess.

    If it isn't broken...modify it anyway! http://www.DazeCars.com https://galaxieforum.boardhost.com
       •Thread Starter
     

    10/02/2020 10:51 AM  #5

    BobE
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    From: White Plains, NY
    Registered: 4/04/2013
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    Re: Ford has me a little irritated (piston ring thickness)

    I understand that the date published for a design change indicates when the design change was "implemented".  As there may be leftover "old" parts still in-stock, these are used until this old stock is gone.  While this may explain the reason why, it doesn't relieve the frustration that we've probably had at one time or another.   

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    10/02/2020 11:07 AM  #6

    Rufus68
    I FYI 24-7

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    From: Knoxville, TN
    Registered: 4/26/2017
    Posts: 892

    Re: Ford has me a little irritated (piston ring thickness)

    I know your thread was rhetorical because it is clear that you have to get different parts; however, I hope venting here helps expel the frustration.  We share your pain.

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    10/02/2020 11:36 AM  #7

    Bolted to Floor
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    From: Houston, Texas
    Registered: 4/01/2013
    Posts: 2,017

    Re: Ford has me a little irritated (piston ring thickness)

    Nos681 wrote:

    Is there a way to tell what size rings are prior to disassembly?

    Dan, if you can read a part number on a piston top through the spark plug hole, you have a chance. I don't think factory Ford pistons have a number. If there is a lot of carbon buildup, you might not be able to read a number. 

    Daze, look on the bright side, the MM ring packs are supposed to be better!!!
     

    John  -- 67 Mustang Coupe 390 5 speed
     

    10/02/2020 7:34 PM  #8

    Greg B
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    Registered: 4/01/2013
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    Re: Ford has me a little irritated (piston ring thickness)

    Are the mm rings "low tension" style rings?  The manufacturers switched to low tension rings when they started using coated pistons.  Time for another round of research.

    If multiple things can go wrong, the one that will go wrong will be the one that causes the most damage.
     

    10/03/2020 12:20 PM  #9

    6sally6
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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,855

    Re: Ford has me a little irritated (piston ring thickness)

    Greg B wrote:

    Are the mm rings "low tension" style rings?  The manufacturers switched to low tension rings when they started using coated pistons.  Time for another round of research.

    Usually! (butt there again...........we are dealing with FoMoCo so .........)
    6sal6
     

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    10/03/2020 5:35 PM  #10

    TKOPerformance
    Hyper FYIFORD ADDICT

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    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,502

    Re: Ford has me a little irritated (piston ring thickness)

    Bolted to Floor wrote:

    Nos681 wrote:

    Is there a way to tell what size rings are prior to disassembly?

    Dan, if you can read a part number on a piston top through the spark plug hole, you have a chance. I don't think factory Ford pistons have a number. If there is a lot of carbon buildup, you might not be able to read a number. 

    Daze, look on the bright side, the MM ring packs are supposed to be better!!!
     

    The only info I've ever seen on a piston from any OEM was cast or stamped into the underside.
     

     

     

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