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Old 05-24-2006, 11:29 PM   #1 (permalink)
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Question Shovelhead compression test question(s)

I just picked up a 1978 Lowrider and the owner has had it since new. He swears that the 9.300 on the odometer is correct. I got it home tonight and did a compression test. Found 150# one the rear and 135# on the front. I added a little oil to the front cylinder and the compression jumped to 165. My questions are: 1. what is good compression for these engines and 2. is it possible to get this much wear in only 9000 miles. From the looks of the rusty chrome and general appearance it looks like he wasn't big on maintanance but it seems like the rings have worn in a short time. 3. Is the difference in compression from front to rear anything to worry about or run it like it is? What do you think?
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Old 05-26-2006, 02:38 PM   #2 (permalink)
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Your compression is fine. The factory shop book calls for anything over 90psi with not more than 30psi beetween the two cyliders.I have a 79FXS that has been in the family since new with 28,000 mi and I get 110 psi from both jugs.
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Old 05-26-2006, 02:58 PM   #3 (permalink)
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Thanks

Ted, Thanks for the reply. I guess it will be a long time before the compression gets to where I have to worry about it. Paranoid sometimes. TH
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