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  1. #1

    Default E7's with Flat Topped Pistons?

    Hey, long time lurker but first time posting here. I figured some of you might have some personal experience here. I have an '86 mustang 5.0, 1990 E7 block but for some reason the guy that put the block in decided to keep the forged flat top pistons from the '86. Well it's been leaking a ton of coolant out the exhaust and i think i might have a cracked head so i'm pulling the heads off and gonna have them checked out.

    So i was thinking if one of them is cracked, maybe i could try dropping some E7 heads on it. It has the E6's right now that everyone seems to hate and i know o'reillys sells e7's for the same price as e6's. So what do you guys think? I know these pistons don't leave enough clearance for most heads but could i clear E7's? or is that a big No?

    Thanks in advance

  2. #2
    FEP Power Member
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    search for that. A dozen opinions - some work - some don't. Same honest generic answer - clay and check - otherwise - u won't know....

    Jason

  3. #3

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    I have the 86 forged flat tops in my car. I have had E7 heads on and now have gt-40s. You just have to fly cut the pistons which can be done in the car. look on youtube for videos because I don't have any.

  4. #4

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    Quote Originally Posted by 85mcLaren View Post
    search for that. A dozen opinions - some work - some don't. Same honest generic answer - clay and check - otherwise - u won't know....

    Jason
    Crap, alright. I guess i could always exchange the heads for the E6's if they don't clear. Thanks

  5. #5

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    E7's cleared on my block, ull have to clay it to make sure.

  6. #6
    FEP Senior Member
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    That is very good advice. I remember in high school a guy had a really fast 86. It was all stock with E7 heads. He had absolutely no problems. Another guy thought he would do the same thing to his 86 and it was nothing but trouble. It had engine noise from the get go. He ended up messing up the entire engine because he thought it would magically fix itself.
    1986 Notchback, Recently repainted Light Regatta Blue(3J) and getting put back the way it should be. It had a 3.8 and a C5. Now it has a 5.0 and a T5.

  7. #7
    FEP Super Member TWR2003's Avatar
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    Like everyone else has told you you will need to check (clay). But for the record if the rest of the setup is basically stock (intake, exhaust, cam ,etc) you really wont notice any difference on the seat-of-the-pants meter. The E7s arent exactly Gods gift to performance. Yes E6s s*ck but E7s only s*ck a little less. Better saving your $$ for a set of aluminum aftermarket heads. A used set can be had for not too much more.

    Good luck
    T
    MF: Shoot pool Fast Eddie.
    EF: Im shootin' pool Fats. When I miss you can shoot.

  8. #8
    FEP Super Member anthonydalrymple's Avatar
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    Nothing new too add..... I did the same thing many years ago; E6 motor, E7 heads, stock cam, & I still had to flycut the pistons...
    '89 5.0 5-speed 'vert, seeing rust for the 1st time in it's life as well as 4,500+ elevation....

  9. #9

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    Quote Originally Posted by TWR2003 View Post
    Like everyone else has told you you will need to check (clay). But for the record if the rest of the setup is basically stock (intake, exhaust, cam ,etc) you really wont notice any difference on the seat-of-the-pants meter. The E7s arent exactly Gods gift to performance. Yes E6s s*ck but E7s only s*ck a little less. Better saving your $$ for a set of aluminum aftermarket heads. A used set can be had for not too much more.

    Good luck
    T
    Yeah i know the E7's are poop too but anything's better than E6's. The only aftermarket heads that clear these pistons are the twisted wedge trickflows and they're out of my budget right now. I saw a set on ebay a couple weeks ago with rockers and all ready to bolt on for only $800 but i didn't get on it quick enough. I'd like to upgrade to them eventually.

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