86 4.0" 302 piston selection.

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  1. #1

    Default 86 4.0" 302 piston selection.

    I have a 302 out of a 1986 LTD. It has flat top pistons and no HO crank. I had the block hot tanked checked, and it is still in spec (it still had the hatch marks on the cylinder walls). I'm putting it in a 1966 mustang coupe and would like to bolt on one of the trick flow top end kits. I haven't committed to a street burner or track heat kit.

    Since the block is still in spec and none of the cylinders are egg shaped I'd like to swap the flat top pistons for pistons with reliefs cut in them. I need help finding a 4.0" piston with the right size relief. I checked trick flow's web site and all I saw was a 4.030".

    Also I'm looking for any other things mechanically on the engine that I might have to change out. The pistons were the only thing that looked like they would a be a fitment issue. I plan on switching to MAF, slightly bigger injectors and a tuned ECU, but would like to try to stay simple. All I'm trying to make is a dependable driveable build with more horsepower than stock.


    -Chris

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  3. #2

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    Quote Originally Posted by Crit View Post
    ... I had the block hot tanked checked, and it is still in spec (it still had the hatch marks on the cylinder walls). ...
    Hot tanking a block is not how to check its condition or serviceability, Chris. The only thing you have done is wash off the years of accumulated crud.

    Quote Originally Posted by Crit View Post
    Since the block is still in spec and none of the cylinders are egg shaped I'd like to swap the flat top pistons for pistons with reliefs cut in them. I need help finding a 4.0" piston with the right size relief. I checked trick flow's web site and all I saw was a 4.030".
    How do you know the cylinders are round? What are the bore dimensions at the top of the stroke, midway down the bore and at the bottom of the stroke? Who took the measurements and did they measure at 12 / 6 o'clock and 3 / 9 o'clock at each of the measuring points? BTW did they use torque plates when they measured? What is the deck height?

    Quote Originally Posted by Crit View Post
    Also I'm looking for any other things mechanically on the engine that I might have to change out. The pistons were the only thing that looked like they would a be a fitment issue. I plan on switching to MAF, slightly bigger injectors and a tuned ECU, but would like to try to stay simple. All I'm trying to make is a dependable driveable build with more horsepower than stock.


    -Chris

    Before we start to look for "any other things mechanically" it might be prudent to establish a budget in $ that you are going to be working with. BTW 4" bore pistons are easily obtainable from any of the piston manufacturers.


    Ed

  4. #3

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    Ed,

    I asked the machine shop to give the block the once over when I brought it to them to hot tank it and tell me if it needed any work. They didn't indicate that it needed any work. I wasn't physically there when they checked it so I'm going off the word of the machine shop that was given a open checkbook for work. I'm away from home at the moment, so I don't have the inspection sheet right in front of me.

    I'm aware that there are plenty of places that sell 4" pistons, but they come in every kind of configuration you can think of. I'm just looking for something that will work with the trick flow heads. If I need to give more information on the block beyond its a stock 302 then tell me exactly what I need to give you.

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  6. #4

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    Quote Originally Posted by Crit View Post
    Ed,

    I asked the machine shop to give the block the once over when I brought it to them to hot tank it and tell me if it needed any work. They didn't indicate that it needed any work. I wasn't physically there when they checked it so I'm going off the word of the machine shop that was given a open checkbook for work. I'm away from home at the moment, so I don't have the inspection sheet right in front of me.

    I'm aware that there are plenty of places that sell 4" pistons, but they come in every kind of configuration you can think of. I'm just looking for something that will work with the trick flow heads. If I need to give more information on the block beyond its a stock 302 then tell me exactly what I need to give you.

    Use this as a starting point. There is lots more but this is a good starting point.

    Quote Originally Posted by eschaider View Post
    ...How do you know the cylinders are round?

    What are the bore dimensions at the top of the stroke, midway down the bore and at the bottom of the stroke?

    Who took the measurements and did they measure at 12 / 6 o'clock and 3 / 9 o'clock at each of the measuring points?

    BTW did they use torque plates when they measured?

    What is the deck height?


    This is more important than anything else;

    Quote Originally Posted by eschaider View Post
    Before we start to look for "any other things mechanically" it might be prudent to establish a budget in $ that you are going to be working with.


    Piston availability is not an issue whatsoever! All you have to do is tell the piston manufacturer the engine you are building for then, ...

    Quote Originally Posted by eschaider View Post
    BTW 4" bore pistons are easily obtainable from any of the piston manufacturers.


    Ed

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