tag:blogger.com,1999:blog-5415584649217620448.post8019766323286131521..comments2021-07-09T05:43:57.405-07:00Mikehttp://www.blogger.com/profile/17227485615141686252noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-5415584649217620448.post-18550363857685532052021-05-15T12:41:42.281-07:002021-05-15T12:41:42.281-07:00It seems like it would matter depending on where the check valve is located. If the check valve were screwed into the spark plug hole, then hose volume might not matter. But if the check valve is between the hose and the gauge, then it seems like the pressure in the hose would bleed off between each compression stroke, so then it would matter a great deal.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5415584649217620448.post-74706632061283667012017-09-22T16:49:49.065-07:002017-09-22T16:49:49.065-07:00I agree, the compression indicated on the gauge is from each individual stroke, but it is cumulative owing to the check valve in the line. Therefore the static line pressure has virtually no effect on the final reading. This is proven by the small increases in pressure for each stroke of the engine.Anonymoushttps://www.blogger.com/profile/15724655302115189232noreply@blogger.comtag:blogger.com,1999:blog-5415584649217620448.post-28145260183615052472017-09-22T13:29:34.801-07:002017-09-22T13:29:34.801-07:00Hi Bob, Even though you do turn the engine over multiple times during a compression test, the compression that builds up only lasts for that compression stoke as the piston continues to travel back down the cylinder relieving that compression and then on the next stoke of the piston the exhaust valve is open so no compression can build up. During a compression test each compression stroke is a one shot deal which is why you need to have a one way valve between the cylinder and the pressure gauge to trap the pressure on each compression stroke.<br /><br />MikeMikehttps://www.blogger.com/profile/17227485615141686252noreply@blogger.comtag:blogger.com,1999:blog-5415584649217620448.post-60372849567690990442017-09-22T08:24:59.227-07:002017-09-22T08:24:59.227-07:00I looked at your reasoning and agreed with it. Then I thought, wait. Don&#39;t we turn the engine over a couple of times? And with this, doesn&#39;t the compression increase? The compression pressure is increasingly charging the tester&#39;s line and gives us a more complete reading. The initial atmospheric pressure in the tester line is averaged with the compression pressure and makes the volume of the line insignificant. Do you agree?<br /><br />BobAnonymoushttps://www.blogger.com/profile/15724655302115189232noreply@blogger.com