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Thread: Nailhead guys, do these work?

  1. #1
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    Nailhead guys, do these work?

    Found this listing on Ebay, do they work, are they necessary, and will they do any harm?

    This listing is for a set of 4 new intake manifold gasket, exhaust crossover portplugs to fit Buick Nailhead engines 1957-1966.

    These can plugs can be used with 364, 400, 401, 425 CID Buick Nailhead engines.
    Intake manifold and gasket NOT included.
    These plugs will prevent the exhaust ports in your intake manifold from boiling the fuel away in your carburetor which then causes a hard starting condition which is common in all Buick Nailhead engines.
    Keep your carburetor and fuel cool which will give you an additional 18horsepower and also prevent hard starting.
    We also sell the intake manifold gasket in our eBay store, part number 111-103.
    The nuts used in this kit are the locking style, which will prevent them from coming loose and falling into your engine.

    http://www.ebay.com/itm/1957-1966-Buick-Nailhead-Intake-Manifold-Exhaust-Crossover-Port-Plugs-V8-Engine-/302348884224?fits=Make%3ABuick&hash=item466565d900 :g:SH0AAOSwgv5ZQDO~&vxp=mtr

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    I made my own a few years ago, and while it did not affect performance there was apparently an incomplete seal that allowed some exhaust gases to enter the manifold. After a year of use I found the intake manifold full of rusty water (water is a byproduct of combustion). A better solution for prevention of carb percolation is to remove the heat riser in the exhaust manifold and plug the exhaust passages under the carb.

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    Thanks for the response, does plugging the exhaust passages under the carb have any effect on performance or drivability? What would you suggest to use to plug them up?

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    Why spend $9.99 for $0.99 worth of common hardware?

    Plugging up the heat holes in the intake manifold gasket could be expected to cause warm-up drivability problems. This assumes original stock components are in use.

    Buick issued a service bulletin in '55 (attached) for complaints of rough idle, bucking, or missing. The cause was found to be excess flashing left in the cylinder head exhaust crossover passage. The excess flashing blocked off exhaust gas flow same as the bolts would.

    Gaskets on cars w/automatic used 1/2" heat holes; synchromesh had 5/8" holes.

    It seems the classic way to address vapor lock problems was to concentrate on improving insulation between the carb base and manifold via gaskets or spacers. Claims of added horsepower are not believable. Where is research data to support 18 HP extra?
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    What has been, can be again. (Bob Wills, 1942)

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    Great responses guys, just the other day I was driving my 60 Lesabre (401 4bbl) hot day, high humidity, shut off the car and after about 5 minutes I went to start it again and it was just a little hard starting and long crank-over time but no real problems. Never a problem starting after sitting a while but start-ups after a short time sometimes are taxing.

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    Quote Originally Posted by TODD View Post

    It seems the classic way to address vapor lock problems was to concentrate on improving insulation between the carb base and manifold via gaskets or spacers.
    Won't work for vapor lock, carb percolation, yes. Vapor lock occurs on the suction side of a fuel pump (treated by installing an electric pump near the tank).
    To block the heat passages under the carb, tap and install appropriate pipe plugs...something for you to figure out.

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    Quote Originally Posted by OZ40 View Post
    Great responses guys, just the other day I was driving my 60 Lesabre (401 4bbl) hot day, high humidity, shut off the car and after about 5 minutes I went to start it again and it was just a little hard starting and long crank-over time but no real problems. Never a problem starting after sitting a while but start-ups after a short time sometimes are taxing.
    After some years the brushes and windings in the starter will expand when they get hot. As the engine cools, so does the starter motor and those windings contract and your starter performs again. Letting it sit works or pour some cool water over the starter motor to cool it off if you're in a hurry. Is the heat shield still in place? I had the starter in my 63 rewound to "high torque" specs, no more problems.

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