MTS3 Mileage Cam

Discussion in 'Big Block Cadillacs' started by peter dennis, Feb 28, 2018.

  1. El Diablo

    El Diablo Active Member

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    What vehicle(s) do you drive?:
    1959 Cadillac Sedan deVille
    Here's what I'm thinking and you tell me if this will work or if my idea is flawed.

    Angle mill the bottom of the head with an emphasis on the outter edge (removing more material as you get closer to the exhaust side). This will make the intake side "lay over" a little more. This would open up the distance from the tops of each cylinder heads intake face while not really affecting the bottom. (Basically widening the angle of the "V").

    You would then machine the intake to match the corresponding angle of the heads. You could then use thicker or double intake gaskets to fill the resulting wider gap between the intake and heads, or deck the block to bring the heads down a bit which would not change the angle of the "V", but would reduce the gap. This would also change the chamber volume & compression ratio.

    This should bring the stock head / 2115 intake mating angle closer to stock.

    Only problem would be getting the head bolt holes back to the correct angle since the head will be laid over a bit.
     
    Last edited: Mar 11, 2018
  2. peter dennis

    peter dennis New Member

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    What vehicle(s) do you drive?:
    2001 holden, 1974 cadillac sedan deville
    I absolutely agree Dave. Now that I know about the manifold to port mismatch, there's no way I could just leave it alone even if it took hours in each chamber and hours in each port. As said by 8ad-f85, it's the low hanging fruit and as my thinking has it, it's all quick easy and cheap compared to building the car it's going in.
    Pete.
     
  3. 8ad-f85

    8ad-f85 Well-Known Member

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    Addressing the angle milling...
    Correcting the bolt bosses is easy, even in a drill press.
    Set it on the table and stab the tops with a piloted spot face a smidge, or slowly with an endmill on a B port.
    Angle milling other types is pretty common (used to be), there's a limit to the amount of angle you can tilt it before other issues rear up.
    You can ream the holes quite a bit before water is found or just the top and bottoms of the bosses and let a reduced bolt shank miss the middle.
    A 7" wide head loses about 1/8" (?) on one side per single degree if done across the entire length, it only needs to seal to the water on the deck so it could be done on smaller radius and reduce the amount of deck cut per degree.
    If you were to have a bolt that long, it would need an extra 1/8" room on one side.

    The issue of the flow angle mismatch to the intake is much more than a degree, so it still needs hand work.
    The fact that the intake can be spacer plated up to force more port match is a gift in itself, up to the point that the flat surface at the head needs to be addressed among other things if you go further.
    When the head opening is raised with a die grinder, several degrees of transition at a time can happen in about an inch inside the ports, without affecting the fit of the head and all of the components that locate from it.

    There have been makes shown to gain power with a reverse-angle mill, to lay the valve back and away from near vertical, to help the short turn radius as the flow tries to get into the cylinder. Think about the Hemi layout...
    Kind of the flaw we deal with on the Caddy is that a near vertical valve begs for a port raise, but the hood lines don't allow it in the Cads these went into.
    Porting to a raised head makes you look like a hero, it can do so much to improve flow .

    In no way would I discourage anyone from trying. There might be some benefits not considered.
    This pparticullar problem is such an easy thing to solve by hand though.
     
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  4. dave brode

    dave brode Well-Known Member

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    2 more cents.

    If the block and heads aren't cut much, and the stock type tin gasket is used, the edel "might" not hang below the head roof. Paper gaskets, forget it, it'll be too high. Worse with surfaced heads/block. Can fix issue by cutting the intake, but most shops charge way too much to do that.
     
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