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did a cranking compression test

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Old Nov 29, 2003 | 06:31 PM
  #1  
1991tealRSt-topGuy's Avatar
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
did a cranking compression test

here were my results

1 195
2 205
3 200
4 210
5 200
6 210
7 205
8 210


all in all it turned out pretty well i think
in general it seems kinda high but the engine did start out with 9.3:1 and the previous owner claimed the heads were shaved

add that to a low end torque cam (XR252) and i guess that warrants the rather high cranking compression

engine runs great too, sucks i found an oil leak, but thats good in a way because i have to add a quart a month, thought i may have been burning oil, but that idea is now laid to rest
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Old Nov 29, 2003 | 08:53 PM
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Vader's Avatar
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Cranking compression tests always have numerous variable due to battery and starter condition, enging temperature, valve timing, cam profile, altitude, etc. The most important factor is the difference in the results, from the highest to the lowest cylinder tested. The old standard allowance is for no more than 10% variation from highest to lowest. Yout 7% looks very good by that metric.
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Old Nov 29, 2003 | 11:00 PM
  #3  
1991tealRSt-topGuy's Avatar
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
cool

i did it when the engine was warm (20 minute drive home from work)
the starter is brand new and it does spin rather fast

and i am 2 miles inland from the atlantic ocean

and the smaller duration of the cam leaves for less time the valves are open
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