Is this a fresh engine rebuild ? How are you measuring the temps ?
If cylinder PSI/leakdowns are good, clean oil cooler fins, and no corroded holes inside the intake manifold...... perhaps a vacuum leak on one of the upper/middle valve cover ‘hollow’ bolts; either for the distributor or wiper tubing. I use a IR temp gun on each exhaust port - they are within 20F degrees.
This is not a new build,but only has about 100 miles on new motor.One head is cool to touch ,other is hot enough where you can't hold your hand on it for long.Motor at fast idle for half hour,motor temp was 130. Thank you for your response.
The Mighty Mite uses a peculiar 104 or 107 CID air Cooled V-4 much like a Wisconsin chipper engine, mine was only happy when it snowed, was below zero, or raining like hades. The problem is that they put the oil cooler on the intake side of the cooling air circuit instead of the exhaust side, so it tends to elevate the engine temperatures when you least want it. Uncle tried to dump the M422's on the Shah of Iran, but the Revolution took care of that deal...... Good luck, they are too light for a boat anchor and parts are difficult to find, or were in the late 1970's.....
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