Carbon on pistons
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Carbon on pistons

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    Senior Member Need4Speed77's Avatar
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    Default Carbon on pistons

    A good burn in the cylinder means the whole piston should be covered with carbon correct? What if only the bottom 3/4 of the piston in each cylinder had carbon build up? Would this mean that a complete burn is not being achieved? If so why would it happen and how would you tune or correct for a complete burn?

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    Quote Originally Posted by Need4Speed77 View Post
    A good burn in the cylinder means the whole piston should be covered with carbon correct? What if only the bottom 3/4 of the piston in each cylinder had carbon build up? Would this mean that a complete burn is not being achieved? If so why would it happen and how would you tune or correct for a complete burn?
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    Quote Originally Posted by Need4Speed77 View Post
    A good burn in the cylinder means the whole piston should be covered with carbon correct? What if only the bottom 3/4 of the piston in each cylinder had carbon build up? Would this mean that a complete burn is not being achieved? If so why would it happen and how would you tune or correct for a complete burn?
    Could be a number of thigs, but typically it's related to chamber design and cylinder filling. It's one reason we wet flow cylinder heads, to see just where the fluid is going.
    What heads? Is there a dome on the piston?
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    Quote Originally Posted by PlacecraftTunnel View Post
    Buy a FORD.. problem solved
    No I would start breaking piston rings then!

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    Quote Originally Posted by steelcomp View Post
    Could be a number of thigs, but typically it's related to chamber design and cylinder filling. It's one reason we wet flow cylinder heads, to see just where the fluid is going.
    What heads? Is there a dome on the piston?
    RHS 360's and yes there is a dome but I am not sure ehat size exactly. I would have to dig through the build paperwork to find the piston specs.

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    gn7
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    It can be caused by a very tight quench and a cold head. Is not real uncommon in boat engines. Less so in a car.

    But if your talking about WASHED, thats another story.



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    Quote Originally Posted by gn7 View Post
    It can be caused by a very tight quench and a cold head. Is not real uncommon in boat engines. Less so in a car.

    But if your talking about WASHED, thats another story.
    Thats what I was looking for. I figured as much. Pistons out of the hole .015 with a .042 gasket is a tight quench. The motor is never run with cold heads though.

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    Quote Originally Posted by Need4Speed77 View Post
    Thats what I was looking for. I figured as much. Pistons out of the hole .015 with a .042 gasket is a tight quench. The motor is never run with cold heads though.
    Yeah, that could explain it. Thats pretty tight!
    You say never run with cold heads. You mean you run the motor at 180 plus?



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    Quote Originally Posted by gn7 View Post
    Yeah, that could explain it. Thats pretty tight!
    You say never run with cold heads. You mean you run the motor at 180 plus?
    No, I run them at 150. i dont consider that cold. I know guys that run so cold that their temp gauge never comes up.

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    Quote Originally Posted by gn7 View Post
    It can be caused by a very tight quench and a cold head. Is not real uncommon in boat engines. Less so in a car.

    But if your talking about WASHED, thats another story.
    Good point.
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    Quote Originally Posted by Need4Speed77 View Post
    No, I run them at 150. i dont consider that cold. I know guys that run so cold that their temp gauge never comes up.
    In the world of internal combustion engines, thats still cold when it comes to the heads quench pad.



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    Quote Originally Posted by Need4Speed77 View Post
    Thats what I was looking for. I figured as much. Pistons out of the hole .015 with a .042 gasket is a tight quench. The motor is never run with cold heads though.

    At .027 worth of quench, depending on the bore size, skirt design, and how much piston to wall clearance, I'd be looking for where the piston is tapping the head... and possibly "knocking" the carbon off in the quench area.

    Large, inactive chambers and huge piston bumps make for real inefficent burns... hence part of the reason you have to run a shitload of timing advance compared to somethign like an LSx.
    Last edited by six-oh-nine; 11-29-2012 at 09:32 AM.
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    Quote Originally Posted by six-oh-nine View Post
    At .027 worth of quench, depending on the bore size, skirt design, and how much piston to wall clearance, I'd be looking for where the piston is tapping the head... and possibly "knocking" the carbon off in the quench area.

    Large, inactive chambers and huge piston bumps make for real inefficent burns... hence part of the reason you have to run a shitload of timing advance compared to somethign like an LSx.
    That's the thing there is no carbon on the quench area or a very very little amount. The piston is still clean there. The pistons aren't hitting the heads. When I get the heads back I am going to switch to a bit thicker gasket.

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