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Compression / irregularities/ engine balance

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Old Apr 1, 2004 | 10:13 PM
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J.S.J's Avatar
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From: Irvine, California
Compression / irregularities/ engine balance

I did a compression test and found over all it looks good. I do see using a normal compression gage a small difference in the rhythm in one rotor than the other. One seems to have for a lack of better terms a slight glitch in its rhythm compared to the other. My engine builder said this is likely due to balance. He said when all the rotating parts are balanced as a unit this does not happen and its normal for this engine. I need a second opinion on this.
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Old Apr 1, 2004 | 11:24 PM
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From: Gaithersburg, MD / WVU
The rotors are offset from eachother if thats what your saying?
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Old Apr 2, 2004 | 01:04 AM
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From: Irvine, California
I'm not sure how to explain but as the engine is being cranked you should have three compression peeks. I see them in the front rotor. There even and in time over and over. In the rear rotor the compression peeks seem to be unbalanced. Theres a noticeable glitch but not on each rotation. The builder did say in a follow up conversation it could be an apex spring which has not broken in. I will keep an eye on it. I don't have a Mazda factory compression tester. I am guessing it can distinguish between the 3 apexes of each rotor, or at least show more clearly a problem. I am saying if one apex seal is not sealing well but does have some compression the standard compression gage moves so fast its hard to make out a clear measurement. I am sure it makes compression but maybe not as much as the other two on the rear rotor. The engine runs OK and I only have 750 miles on it. Time will tell.
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