1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Compression Test Results

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Old Nov 14, 2004 | 06:53 PM
  #1  
riofrio's Avatar
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Compression Test Results

I did a compression test today... I used a piston compression tester, here are my numbers:

Rotor 1: 110 110 110

Rotor 2: 100 100 75

(numbers in PSI).

Are these somewhat decent??
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Old Nov 14, 2004 | 07:04 PM
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Why did your compression on your second rotor drop. Does that mean that a seal is not sealing right?
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Old Nov 14, 2004 | 07:13 PM
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i believe so calvin, no expert here but i believe that would indicate a bad side seal causing the one chamber to drop off, if it was a bad apex seal 2 chamber would be low since it would blow by is ya follow me. someone who knows for sure chime in?
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Old Nov 14, 2004 | 07:25 PM
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Thats exactly what i thought.... if one would be different than the other 2, then the singular one should be higher. I'm a little confused by this, but I did it twice just to be sure. As far as the numbers go, though... are these good compression numbers?
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Old Nov 14, 2004 | 07:43 PM
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Yes. Comp on my rebuilt motor new housings, the whole shabang, 120 all round.

Sue
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Old Nov 15, 2004 | 12:40 PM
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The one low face does indicate some sort of side seal problem. It is probably due to carbon build up not allowing the side seal to push out and contact the side housing correctly. Maybe an MMO treatment or a steaming (if you are willing to try) may help to free that seal up. The side seals do not recieve a lot of wear, so I doubt that it is worn out. I also think the probability of it being damaged is pretty slim.
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Old Nov 15, 2004 | 01:42 PM
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Rx7carl's Avatar
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Originally Posted by gsl-se addict
The one low face does indicate some sort of side seal problem. It is probably due to carbon build up not allowing the side seal to push out and contact the side housing correctly. Maybe an MMO treatment or a steaming (if you are willing to try) may help to free that seal up. The side seals do not recieve a lot of wear, so I doubt that it is worn out. I also think the probability of it being damaged is pretty slim.
Totally agree, thanks for saving me the typing.
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Old Nov 15, 2004 | 03:50 PM
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Thanks, guys! So, overall does it look like there's no need to worry about a rebuild anytime soon? I'm pretty sure this is the original engine, never rebuilt before, and it's got 160k miles on it.

I'll do a Power Foam treatment a la BigJim this weekend, and see if that frees up that side seal.
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Old Nov 15, 2004 | 04:35 PM
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So what kind of sandwich is that you got there ?
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Old Nov 21, 2004 | 12:24 PM
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It's a Big Kahuna burger.
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