How do I test compression in each cylinder?
10-01-2003, 12:25 PM
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How do I test compression in each cylinder?
How do I test compression in each cylinder? I want to know exactly what it is.
[Modified by bhmyers, 5:42 PM 10/1/2003]
[Modified by bhmyers, 5:42 PM 10/1/2003]
10-01-2003, 12:47 PM
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Re: How do I test compression in each cylinder? (bhmyers)
Get a compression tester, disconnect your coil wire, unscrew sparkplug, screw the compression tester in, turn the engine over a few times, check your reading on your compression tester. If you're looking for information to figure out your compression based on stroke, bore, etc., corvettefaq.com has some article. If you don't have a compression tester, your local Autozone will let you rent one for free, after deposit. :cheers:
[Modified by coldwarrior2000, 5:50 PM 10/1/2003]
[Modified by coldwarrior2000, 5:50 PM 10/1/2003]
10-01-2003, 12:50 PM
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Re: How do I test compression in each cylinder? (bhmyers)
Never done so use this if you like. Pull all the plugs and start at #1. Crank the eng or rotate it by hand, the comp gauge should hold the highest reading. Record it and move on till you have done all eight. I am not sure what 'normal' readings are but they should all be within 10% of each other. If you have one that is way off more then shoot some oil in the the cyl through the plug oil and recheck, if the pressure comes up you have bad rings.
10-01-2003, 01:34 PM
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Re: How do I test compression in each cylinder? (Fevre)
I prefer leak down tests over compression test. Each winter I do a leak down and compare to the year before. Leak down does require a compressor but does not require all the cranking.
10-01-2003, 01:49 PM
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Re: How do I test compression in each cylinder? (bhmyers)
don't forget to do it with full open throttle.
As for coinverting to compression ratio, you can't. The compression ratio is purely a calculated ratio that does not take into account the valve events and it calculates at 100% volumteric efficiency. The DCR DOES take into account the valve events (but also 100% VE after taht) and is more closely related to the cranking pressure but there's no way to convert one to another. As for pressure ranges, 175-1809 / 185 is a good range, lower is too low and higher is too high (street)
As for coinverting to compression ratio, you can't. The compression ratio is purely a calculated ratio that does not take into account the valve events and it calculates at 100% volumteric efficiency. The DCR DOES take into account the valve events (but also 100% VE after taht) and is more closely related to the cranking pressure but there's no way to convert one to another. As for pressure ranges, 175-1809 / 185 is a good range, lower is too low and higher is too high (street)