How much will leaving your throttle closed affect cranking compression?
03-23-2009, 11:37 PM
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what kind of answer is that??? if the engine didnt suck in air it wouldnt have anything to compress.... Obviously the cylinder is filled on the intake stroke and in order to facilitate compression the intake valve closes on compression stroke.
98redbird, you should do compression tests with open throttle just to make sure the cylinder if filled with air. Also the amount of compression is not of real importance as every gauge varies... the important thing is that the numbers are all close to each other. To best determine the condition of the rings and valves a leak down test will tell you much more then a compression test. Compression tests are really only good to make sure there isnt a single bad piston. If you do a test and all cylinders end up with 140-150 psi and one ends up with 80 you know that hole has a problem. basically thats all a compression test is good for.
98redbird, you should do compression tests with open throttle just to make sure the cylinder if filled with air. Also the amount of compression is not of real importance as every gauge varies... the important thing is that the numbers are all close to each other. To best determine the condition of the rings and valves a leak down test will tell you much more then a compression test. Compression tests are really only good to make sure there isnt a single bad piston. If you do a test and all cylinders end up with 140-150 psi and one ends up with 80 you know that hole has a problem. basically thats all a compression test is good for.
