300-36 with a 1206

Discussion in 'High Performance Modifications' started by sooner, Jun 9, 2021.

  1. sooner

    sooner Veteran Member Lifetime Gold Member

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    Does not look like she really will want to seal. Gaskets are shellacked to the heads and have to be this high to align with the port (roof raised .100ish).

    Should I:
    A: Use something to seal the gasket to the manifold
    B: Use the 7101 performer rpm that has more material around the ports. Enough to cover the sealing surface on the gasket anyway.
    C: Just put a nasty single plane on it and call it a day.

    IMG_3897[1].JPG
     
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  2. biker

    biker Veteran Member

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    I've been through that. There is so much movement there with heat/cold cycles, that any sealant you use won't seal for long. I hope someone might know of some type of gasket that is made to seal up that area in a case like this.
    Is there maybe some odd milling of the head or intake that caused this issue? I wouldn't think it should sit that low in the valley to cause that issue.
     
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  3. G72Zed

    G72Zed Veteran Member

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    In some cases when I push the limits, I have used a .120 thick gasket or spacers to lift the intake to centre up the runner, or welded the top runners on the intake, or made an aluminum bridge and pinned it into place.

    The issue is the large change in CSA from the intake runner exit into the head, and when you port to a "1206" with an intake not designed for that size, the taper get's wonky, and you test on the the flow bench and it lies to you as the dyno does not line up, and at the track, most times you loose ET/MPH.
     
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  4. 1980RS

    1980RS Veteran Member

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    Here is what I do when running into this problem. Get a sharp pencil, draw a line around the top of the intake runner at the top of the port. Pull the intake off and see how much gasket area there is to seal the intake, if you have at least 3/8" then just put some sealer on the gasket and run the intake. Works for me every time. Yes getting a different intake will be better but the 300-36 is hard to beat.
     
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  5. sooner

    sooner Veteran Member Lifetime Gold Member

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    Thanks for the replies guys. I think that I will try the pencil trick this afternoon. Also, I think that I should still have a set of 1266's that are the thicker gasket. IIRC they are the same dimensions as the 1206, just thicker.

    I have done some porting to the intake, but yes it does look like the runners will be a bit sketchy with the taller port. I didn't really have to go much wider, but I did have to go taller leaving 1,4,6,7 with the wonky approach. I could drop the floor on them a bit to gain some, but there is not a lot of material on the bottom to work with either.
     
  6. sooner

    sooner Veteran Member Lifetime Gold Member

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    Well, scribed it with a pencil and got .105.

    I did find 1 of my 1266 gaskets, but they are the same height as a 1205. Looks like I would need the 1267.

    The 7101 seems to fit better, and would probably fit even better with a 1267. Never thought about the runner discharge to port problem before...but now it is consuming me. There is not enough material in the 7101 to correct that either.

    Leaning toward picking up a single plane now.
     
  7. 1980RS

    1980RS Veteran Member

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    This is the best dual plane intake for larger port heads from Brodix. You car really open the ports up on this one.

    [​IMG]
     
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  8. 1320feet

    1320feet Veteran Member

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