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Location:
ACT
Registered:
July 2002
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4kc refusing to idle smoothly - valves different colours.
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Thu, 12 February 2004 05:50
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I have been striving for yonks to get my KE55 Corolla idling smoothly. Power delivery is smooth and plentiful (for a 4K!). After doing everything else within my power (which does not include timing as I don't have a light), I decided to pull the head off to see if it could tell me anything, as I was suspecting valve seat recession (?). Anyway, the exhaust valves are covered in a browny-orange material, whereas the inlet valves are black, like the rest of the combustion chamber. I have a spare head which is known to be A1 and its valves are all the smae black colour as the combustion chamber. The engine only has 170 thousand ks on it and doesn't use oil or blow smoke. Someone suggested timing chain but I wasn't sure as I've never come across a 4k with a worn timing chain before. Any ideas?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4kc refusing to idle smoothly - valves different colours.
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Thu, 12 February 2004 06:12
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how unsmoothly does it idle? that is usually due to
manifold or carb air leak.
poor idle mixtures.
poor timing
not enough vac advance.
that kind of thing..
i have seen 4K's run until the timing chain wore through the timing cover! they do wear, but very slowly. if it is a single row, replace with a double row from 3K.
the valve seats are hardened so you can use ULP, and recession is not really a problem.
maybe mixture is too rich? black soot is carbon, and the hotter exhaust valve will burn some of that off.. sounds normal..
so, how badly does it idle? maybe just up idle speed?
Cya, Stewart
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Location:
ACT
Registered:
July 2002
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4kc refusing to idle smoothly - valves different colours.
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Thu, 12 February 2004 06:55
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timing light
K-mart
$50
$40 on a 20% off day
priceless 
heh heh, seriously, they are half decent, i'd be looking to timing before i ripped the head off.. and sure the valve seats will recess eventually... my poor little engine does 5-7K all day and hasn't had valve seat probs.
Cya, Stewart
fwiw, i have about 20 deg static timing, with another 12-15deg vac advance... and then it idles smoothly at about 13-1500 
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Location:
ACT
Registered:
July 2002
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Re: 4kc refusing to idle smoothly - valves different colours.
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Thu, 12 February 2004 07:15
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Thanks Stewart, I may just have to give that a go. It would be great if that is all it is. I'm just a stubborn diy junkie that relishes how far he can get with just his socket set. And what better engine is there to play that game with eh!
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