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Old 03-12-2008, 09:39 AM
red65mustang red65mustang is offline
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Cisco,

"if" the rotating assembly is sealing decent and all is ok, your vac guage will tell you....a rv cam motor should read 25Hg+ when decelerating back to idle from about 3k...read this link for diagnosing a motor with a vac guage (kinda cool, the guages are "animated")

http://www.users.bigpond.com/ergoff/vac1.htm

to get a even more accurate reading, rig your vac guage so you can read it while driving (windshield wiper hose and a T in the manifold vacuum advance line and duct tape it to the windshield?)

"if" the rotating assembly is sealing as it should it will read 25Hg+ (28Hg=really good) and steady(!) when down shifted 3rd to second at 3k rpms "with a load on the motor" (which is really what you want to know, how well is it sealing while actually driving)

"ballpark" with a rv cam your comp test readings should be atleast:
8/1+CR=140-150psi
9/1+CR=140-170psi
10/1CR=180+

the specific cam and how it's installed and at what "altitude" are you doing the test does impact the results you see "some" (ex: a motor that tested 180 at sea level will test around 160 at 5,000 ft)

ps: that link points out just some of the reasons you DO want to have a vac guage "in" your car...to see a new problem immediately

Last edited by red65mustang; 03-12-2008 at 09:46 AM.
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