If it's running OK then generally leave well alone. But sooty plugs
indicate a rich mixture which would be beneficial to correct. What are you
using to set the mixture? With HIFs with no emissions limits it is
generally adjust each carb until they give the same results on the lifting
pin i.e. lift it 1/32" and idle speed should momentarily pick up then settle
back again. If idle just drops then richen, if idle stays high then weaken.
On HIFs you screw the screw in to richen and out to weaken. After adjusting
each carb recheck the other one and readjust as necessary as they are
interdependant. When the carbs are balanced for mixture (for that is what
you have just done, and should have balanced them for air flow first) adjust
the mixture of both carbs by the same amount and in the same direction for
maximum idle speed, then weaken till idle speed just starts to fall, then
richen just enough to restore the idle speed. For emissions controlled
cars, if the CO is too high at the tail pipe, weaken both carbs by the same
amount till you just get the required reading.
PaulH.
-----Original Message-----
From: Bart Niswonger <bart@cs.washington.edu>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 20 November 1999 00:53
Subject: [mgs] heavy soot on plugs, what about valves?
>
>Howdy -- first thanks to all those who responded on my last questions
>about exhaust and jacking. Hopefully soon I will actually get this
>stuff done!
>
>My latest question has to do with what I noticed tuning my car this
>past weekend. I had let it go so long (sorry! (but it was only 3
>months...)) that the plugs became fouled with soot. So I replaced the
>plugs & retuned the carbs (the timing, gap, etc was good). I used
>suggestions from this list when tuning my HIF-4s -- thanks, they sound
>much better, if only I had a muffler without holes.
>
>The question: The plugs were covered in soot. The pistons in the
>carbs had some soot (were blackened). So I cleaned the carb pistons
>and replaced the plugs. What about the valves? Should I worry? Is
>there something I could put in there to "clean" them? Do I really
>want to remove the head and do a valve job? (no). Anything else?
>
>Ideas?
>
>Thanks much
>
>bart
>74.5 rb mgb, sounding a little deep, but getting better.
>
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