Leaky heads
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Joined: Jun 2022
Posts: 58
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From: Sebastopol
Its good. Machine shop said its not the threads, the problem is in the flatness where the plug tightens down to.
But of course its still leaking around the plug, so not the solution!!!
But of course its still leaking around the plug, so not the solution!!!
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Joined: Oct 2019
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From: OH
Wonder how they measured that
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Joined: Nov 2006
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From: la la land jerzey
We made a tool from an end mill that drops in the the thread and uses the thread length as a center guide its 2 pieces - a drilled insert ( pilot ) goes in then the tool so the threads are never in danger of being hurt
Indian - 45 and big twin share a 14mm thread and again some are 18mm < those are easy as a pilot is standard for converting to 14mm plug that most all flatheads have - the guy using the bridge port must be good at what he does or you end up doing nothing but reducing the distance
Indian - 45 and big twin share a 14mm thread and again some are 18mm < those are easy as a pilot is standard for converting to 14mm plug that most all flatheads have - the guy using the bridge port must be good at what he does or you end up doing nothing but reducing the distance
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Joined: Mar 2010
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From: Honah Lee
Has anyone out experience leaky heads at the spark plugs?
Im getting a leaky gas/ oil black looking stuff at the spark plugs, mostly the rear head.
Was told that aftermarket aluminum heads have done this because the boss landing where the spark plug rest isn’t flat. So took to machine shop and had it trued up, but yet still leaking.
Whats the fix?
Im getting a leaky gas/ oil black looking stuff at the spark plugs, mostly the rear head.
Was told that aftermarket aluminum heads have done this because the boss landing where the spark plug rest isn’t flat. So took to machine shop and had it trued up, but yet still leaking.
Whats the fix?
I would thread a plug on my lathe to a snug fit on the thread and a straight section to last word indicator to get it square.
Is your plug not a crush gasket ? The old school 45 bevel?
Now it is normal in 10,000 miles US to see black up the threads on a FI even. Aluminum when hot outgrows steel.
Class 2B threads have more then enough clearance for a crush gasket or 45 seat to square up and seal .
Last edited by Jackie Paper; Apr 28, 2023 at 07:08 AM.
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Joined: Oct 2016
Posts: 322
Likes: 92
From: Cumming, GA
Tool for flat plug sealing surface
They may have used a tool similar to this Time-cert tool. The long piece threads into the head and will determine the proper angle for the sealing surface. The Wider piece slides over the first piece and cuts the sealing surface.
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