log exhaust
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log exhaust

  1. #1
    Eliminated badluck24/7's Avatar
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    Default log exhaust

    Those of you that have log manifold exhaust in their jet boat, how are you mounting the logs? Studs or bolts? Also, gaskets or no gaskets?
    WOOP!

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    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by badluck24/7 View Post
    Those of you that have log manifold exhaust in their jet boat, how are you mounting the logs? Studs or bolts? Also, gaskets or no gaskets?
    Studs or bolts both work well depending on wrench access IMO , most wet log manifolds were originally designed to be "machine fit" (no gaskets) however this requires that both the surfaces (mans and heads) are dead nuts perfect flat so if either is the least bit "snakey" or uneven ,gaskets will be needed between heads and flanges or resurface required , the manifold exits (to risers connections) should always have gaskets plus we use a thin coat of high temp silicone .... Tom

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    tintingsandiego krusn56's Avatar
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    SS allen head and if you are running a ford ...get the through bolt logs. They are the only set I have used that do not warp and cause leaks. I also use a good set of felpro.
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  6. #4
    Eliminated badluck24/7's Avatar
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    Default Update

    New question! How do I remove a broken fitting from the log without damaging the threads? The nipple broke off so when I tried to remove it I could not get it to move at all. Lube, heat, voodoo? What's the trick to remove and not damage threads or the log.
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    Default Trick....

    Quote Originally Posted by badluck24/7 View Post
    New question! How do I remove a broken fitting from the log without damaging the threads? The nipple broke off so when I tried to remove it I could not get it to move at all. Lube, heat, voodoo? What's the trick to remove and not damage threads or the log.


    The "trick" is a shop with a EDM machine. Electro Discharge Machining uses electrical current, usually under oil for cooling, to burn out the offending material. If done properly it will not damage the threads at all... Another note, some logs require a stainless backing plate for the gasket between the log and riser. A gasket only MAY bust out under water pressure, and then leak internally/externally. The external leak is just a pain in the ass, the internal may not be seen, and could allow water into the exhaust ports which has been known to break the heads off valves.... You may have to make the backup plates, but once installed correctly they should last a long time.....
    Ray
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  8. #6
    tintingsandiego krusn56's Avatar
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    I have used a small air saw to cut into the fitting at a couple spots. This weakened it enough for me to tap it with a small chisel till it broke off. Its probably a brass crome plated fitting.
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    History Repeating Storz's Avatar
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    stainless allen head bolts on mine.
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    Senior Member ol guy's Avatar
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    Once you clean up the removal problem, use a good gasket and anti sieze compound for the next time. stuff warps in a marine app and things go down hill from there. Main thing is a good anti-sieze on ALL bolts or fittings envolved. You are dealing with dissimular metals and a marine electrolosis situation. There is nothing wrong with logs (even in a performance app) You just need to realize the hot and cold factor of the marine app. M

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    Default gasket type and sides

    i've been using felpro on the BBF with the perforated metal on one side. i think i've been putting that on the log side. is that what y'all would do? the instructions from felpro say to put it on the manifold side but i'm assuming they mean for a cast iron automotive situation.
    thanks.

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