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Other than a couple of holes here and there, the reman G200 head I received looked identical to the G180 head. I've gone thru and made every part of the emissions system function properly, I even have a brand new mixture control valve. My engine unfortunately seems to occasionally misfire at idle. I am trying to get the LUV to pass california smog and I am scratching my head as to which direction to go now. I am starting to wonder of the G200 head made significantly lower compression or something. Does anyone have any input as to stop the cough-in-the-idle blues?

MCV - works
EGR - operates properly
Carburetor - in theory was rebuilt a year ago (I do know that the jets are clean however)
Ignition system - timing set, 50 degrees dwell, new plugs, new wires, coil sparks strong
exhaust check Valve - nothing looks broken
air pump - pumps
exhaust air supply valve - seals when its supposed to and opens when its supposed to


The only thing I can notice is that there is a little play in the carburetor primary shaft

What part did it fail? Nxo, C0, hydrocarbons, etc? Post the results so we can help.

If I remember correct the G 200 head does lower the compression on the G 180 motor. Don't worry about the idle, Calif smog test does not use a idle reading.

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yeah a g200 head on a g180 bottom end will make it have really low compression.

ive had to run 2 engines like that and they were pretty gutless.

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"but its that gut feeling of you're drawn to what feels right for yourself and what you're passionate about..."

Thanks for the replies.

California smog still uses the idle/2500 test in non-enhanced areas like where I live. In sacramento/bayarea/LA they do yes use the enhanced test that is done on a dyno.

Sorry to not post the results.
Idle is at 768 rpm
Carbon dioxide: 9.2%
Oxygen 7.0%
HC's 715 ppm
Carbon monoxide 0.24%

2286 rpm
Carbon Dioxide: 13.4%
Oxygen 0.3%
HC's 98 ppm
Carbon monoxide 1.51%

To me this looks like a random misfire at idle, due to compression/fuel-air mixture/ or weak ignition

If I took the head off again, do you guys think I could mill it enough to bump up the compression, with out messing with camshaft timing too much?

You are correct, readings show a miss at idle, a lean missfire. Adjust the mixture screw out about 1/8 to 1/4 turn, also idle specs should be 900 rpm on that engine. This should bring down the oxygen readings a bit and bring up slightly the carbon monoxide. Too much oxygen means an incomplete burn (lean)in the cylinders.