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  1. #1

    Default Non H.O to H.O piston/rod swap?

    Found out my 84 Mustang has a 91 Non H.O Crown Victoria engine in it. My plan was going to upgrade the Heads/Cam thinking i had a legit 91 H.O engine. Question is can i just swap out the piston/rod assembly from a 87 and up H.O engine and not touch the crank or will I need to balance the assembly. I'm Thinking since the Crank is the same from a H.O and non H.O just to leave it alone and being these engine are externally balanced, does this sound right?
    1984 Mustang Convertible 5.0 5spd

    2000 Mustang GT Convertible Procharged

    2005 Mustang GT Full Bolt On's

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    FEP Supporter Broncojunkie's Avatar
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    I believe that would be a lot of work for little benefit, other than the forged pistons. If you feel you need forged pistons, I would suggest buying new pistons and rods (along with new bearings and upgraded rod bolts). If you're sticking to naturally aspirated, then the cast pistons will be fine. I can't seem to find info on compression ratios of HO vs non-HO, but I'm betting there's not much difference (if any). Some smaller-chamber aftermarket heads will increase flow and cr dramatically. Your cam choice will most likely switch you to the HO firing order. As long as the current engine is healthy, just do heads, cam, intake, etc and enjoy.
    79 Pace Car - 331, t5
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    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by stang80s View Post
    Found out my 84 Mustang has a 91 Non H.O Crown Victoria engine in it. My plan was going to upgrade the Heads/Cam thinking i had a legit 91 H.O engine. Question is can i just swap out the piston/rod assembly from a 87 and up H.O engine and not touch the crank or will I need to balance the assembly. I'm Thinking since the Crank is the same from a H.O and non H.O just to leave it alone and being these engine are externally balanced, does this sound right?

    The Crown Vic engine will have different clearances for non forged pistions, so a swap over is unlikely without re-establishing clearances to Forged OEM 1991 spec from a 5.0 HO.



    Double check:-


    1. Check head castings if OEM original. E6SE = 1986 (all passenger cars) or 1987+ non-H.O. (passenger cars)
    2. Cam, if OEM, is non HO firing order
    3. If engine is OEM, Grey pan, forged. Black pan, Hypereutectics
    Quote Originally Posted by Hissin79
    Starting in late '92 is when the switch to hypereutectic pistons was reportedly made. Before that, aero foxes had forged slugs.

    The old quick and dirty visual test is if the motor has the original and unmolested oil pan, if it is grey in color, that suggests forged slugs. If the pan is black, that suggests hypers.
    4. E7TE = 1987-90 (all passenger cars and trucks), after that, F1xx, post 1990

    5. The forged piston part numbers are:
    1985: E4ZE-6110-SA or SB; first year 5.0 got forged pistons, 2 valve reliefs cut into the tops and compression stayed 8.4:1
    1986: E6ZE-6110-BA No valve reliefs
    1987-92: E7ZA-6110-CA, some have a PA suffix. Forged four eye brow.

    Good fortune tracking the exact origins.

  4. #4

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    What exactly are you trying to achieve?
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  5. #5

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    The Engine block is F1SE, Heads are E6SE and pistons are dished non valve relief as verified by using my borescope. I do not want to flycut these stock cast pistons. I plan do upgrade to AFR190 Heads and a E303 cam which most likely not work with the current pistons as there will be PTV interference. I just picked up a 1985 OEM Forged Piston set with Rods along with the OEM crank and will stuff the Pistons/Rods in the block and check the existing crank for wear, if all good then leave the crank in place, Of course all new bearing throughout.
    1984 Mustang Convertible 5.0 5spd

    2000 Mustang GT Convertible Procharged

    2005 Mustang GT Full Bolt On's

    2002 Vette Convertible Vortech on Methanol

  6. #6

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    Where is the parts number located on the piston? Is it under the crown? I need to verify the 85 Pistons just to see if they are 1985 or 87 and up
    Last edited by stang80s; 05-02-2021 at 05:42 PM.
    1984 Mustang Convertible 5.0 5spd

    2000 Mustang GT Convertible Procharged

    2005 Mustang GT Full Bolt On's

    2002 Vette Convertible Vortech on Methanol

  7. #7
    FEP Supporter Broncojunkie's Avatar
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    What makes you think you will have ptv clearance issues? That's a pretty mild cam. I couldn't imagine it being a problem. I'm pretty sure folks have ran the e303 with the 86 HO flat top pistons (no valve reliefs). Anyway, seeing as how you have the rods and pistons already, it wouldn't hurt to upgrade while you're going through it.
    79 Pace Car - 331, t5
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  8. #8
    FEP Super Member bwguardian's Avatar
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    Quote Originally Posted by Broncojunkie View Post
    I believe that would be a lot of work for little benefit, other than the forged pistons. If you feel you need forged pistons, I would suggest buying new pistons and rods (along with new bearings and upgraded rod bolts). If you're sticking to naturally aspirated, then the cast pistons will be fine. I can't seem to find info on compression ratios of HO vs non-HO, but I'm betting there's not much difference (if any). Some smaller-chamber aftermarket heads will increase flow and cr dramatically. Your cam choice will most likely switch you to the HO firing order. As long as the current engine is healthy, just do heads, cam, intake, etc and enjoy.
    Forged pistons...I believe they are the hyper units in that year...
    HAD
    '82 GT monochromatic (red)...black cloth

    HAVE
    '85 GT vert two tone (white on charcoal)...white leather
    '00 F350 two tone (white on silver)...gray cloth
    '00 Excursion Limited two tone (white on tan)...tan leather...wifes ride
    '08 Taurus Limited ice blue...tan leather...daughter ride
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  9. #9
    FEP Super Member bwguardian's Avatar
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    Quote Originally Posted by stang80s View Post
    The Engine block is F1SE, Heads are E6SE and pistons are dished non valve relief as verified by using my borescope. I do not want to flycut these stock cast pistons. I plan do upgrade to AFR190 Heads and a E303 cam which most likely not work with the current pistons as there will be PTV interference. I just picked up a 1985 OEM Forged Piston set with Rods along with the OEM crank and will stuff the Pistons/Rods in the block and check the existing crank for wear, if all good then leave the crank in place, Of course all new bearing throughout.
    I have the E303 cam in my engine with stock 1985 slugs and GT40p heads and its been all good.


    Quote Originally Posted by stang80s View Post
    Where is the parts number located on the piston? Is it under the crown? I need to verify the 85 Pistons just to see if they are 1985 or 87 and up
    The piston parts number is in the center top portion of each slug...along with the oval Ford signature below...as seen in a picture of my stock 1985 short block power plant as attached...

    Name:  Stang engine short block.jpg
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    Last edited by bwguardian; 05-03-2021 at 12:23 PM.
    HAD
    '82 GT monochromatic (red)...black cloth

    HAVE
    '85 GT vert two tone (white on charcoal)...white leather
    '00 F350 two tone (white on silver)...gray cloth
    '00 Excursion Limited two tone (white on tan)...tan leather...wifes ride
    '08 Taurus Limited ice blue...tan leather...daughter ride
    '08 Edge Limited white sand tri-coat metallic...tan leather...other daughters ride

  10. #10
    FEP Senior Member OX1's Avatar
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    Quote Originally Posted by bwguardian View Post
    Forged pistons...I believe they are the hyper units in that year...
    Weren't 85's these forged one's?

    1985: E4ZE-6110-SB
    86 Capri, 5.0, 5Spd, A9L QH/BE, 47 lb Inj PMAS 3" MAF, Single T44 Turbo, Front Mount IC, TW170,
    Stock Cam, Explr Intake/TB, 1.7 Rockers, CF dual friction clutch, 3" DP, 2.5" full Exh, 3.27, 11.932 @ 115.78
    84 LTD, 331-10:1, TW170/Exprl Intake, 47 lbs inj/80 mm LMAF, Full Duals, Quarterhorse, Vortech 7PSI, Lentech AOD, 5 lug Mk VII brakes/rear, Eibach Sway bars, Cobra HB (dads ride, but I fix it )

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    FEP Power Member mcb82gt's Avatar
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    Quote Originally Posted by OX1 View Post
    Weren't 85's these forged one's?

    1985: E4ZE-6110-SB
    I thought the 85s with 4 barrel were forged pistons.
    Mike

    Now stang-less.

    88 Cougar 5.0

  12. #12
    FEP Super Member bwguardian's Avatar
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    Quote Originally Posted by OX1 View Post
    Weren't 85's these forged one's?

    1985: E4ZE-6110-SB
    Yes, the 1984 and back were cast slugs...basically flat tops with 4 valve reliefs. In 1985 they were the same design...flat top with 4 valve reliefs...but forged. The 1986 units did away with the 4 valve reliefs. In 1987 they were still forged but had a center dish relief in the top. What I was talking about in the aforementioned post is that later on they went to the hyper slugs...
    HAD
    '82 GT monochromatic (red)...black cloth

    HAVE
    '85 GT vert two tone (white on charcoal)...white leather
    '00 F350 two tone (white on silver)...gray cloth
    '00 Excursion Limited two tone (white on tan)...tan leather...wifes ride
    '08 Taurus Limited ice blue...tan leather...daughter ride
    '08 Edge Limited white sand tri-coat metallic...tan leather...other daughters ride

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