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12-14-2016, 06:48 PM | #1 |
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some compression testing advice
Wanna do my first compression test. Have a pretty good idea but would like to first run it by some more experienced minds. I am thinking let it warm up some, plugs out, key off, engage starter from under hood and check gauge. The car is a 31 deluxe roadster and is my avatar pic. The engine is stock with a high compression head, maybe a comp. test will give me an idea of how high. Motor has been redone in 97 and has about 2500 mi. since a full restoration. Had this car about ten years and have it running great thanks to a lot of members who have helped out from timing to corn head grease. I am an older fella but a good learner.
thanks again dutie |
12-14-2016, 07:16 PM | #2 |
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Re: some compression testing advice
Sounds like you're just checking for the fun of it? Sounds like you have it figured out, might want to hold the throttle wide open also, and cycle 5-6 compression strokes. My old engine has only 45, 50, 50, 50 PSI. I call it compression-depression, you have been warned! 8^)
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12-14-2016, 07:19 PM | #3 |
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Re: some compression testing advice
I have found no difference between WOT and a closed throttle on compression checks. It won't hurt to put a brick on the throttle to hold it open, however. You may want to try both ways (closed and open) and report your findings back here.
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12-14-2016, 07:27 PM | #4 |
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Re: some compression testing advice
Same here no difference..... just pull the throttle lever down if you feel better having the throttle open....i usually go 3 bumps
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12-14-2016, 07:34 PM | #5 |
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Re: some compression testing advice
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12-14-2016, 07:37 PM | #6 |
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Re: some compression testing advice
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Looking for uniformity Larry |
12-14-2016, 07:43 PM | #7 |
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Re: some compression testing advice
One can tell just by the way an engine idles, and the sounds of it if the motor is tired.. a nice smooth running motor at a low idle the compression test will be fine.
All gauges are not created equal Last edited by Mitch//pa; 12-14-2016 at 07:57 PM. |
12-14-2016, 10:47 PM | #8 | |
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Re: some compression testing advice
Quote:
If you have a low cylinder, then do the leakdown test to see if the air is exiting out the tail pipe (ex. valve), or the carb (intake valve), or out the oil fill pipe (bad rings). |
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12-14-2016, 11:36 PM | #9 |
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Re: some compression testing advice
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12-15-2016, 01:00 AM | #10 |
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Re: some compression testing advice
I got 70psi stock head and block is sleaved back to standard bore.
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12-15-2016, 05:40 AM | #11 |
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Re: some compression testing advice
Post #7 all compression gauges are not created equal... CA air is also different
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12-15-2016, 09:12 AM | #12 |
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Re: some compression testing advice
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12-15-2016, 09:19 AM | #13 |
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Re: some compression testing advice
does it contain lead and cause cancer? seems everything in California does according to every warning label ever made
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12-15-2016, 09:32 AM | #14 |
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Re: some compression testing advice
Oh, you have no idea. I am a native and I remember when there was NO smog. Sun burnt days of playing in shorts and no shirt in the summer without a care. Now they have polluted everything we have, air, water, food. It's like we are being embalmed before we die so all the funeral parlor needs do is bury us and charge more for that!
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12-15-2016, 10:18 AM | #15 |
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Re: some compression testing advice
Compression decreases with an increase in altitude, less air density to suck in, less to compress. When the readings are not similar from cylinder to cylinder, put a squirt of motor oil in the hole, less than a teaspoon. This will make an improvement when redoing the test on that cyl. IF the rings are bad. The oil won't improve the readings if the valves are leaking.
Last edited by 100IH; 12-15-2016 at 10:25 AM. |
12-15-2016, 11:30 AM | #16 |
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Re: some compression testing advice
[QUOTE=Mitch//pa;1399753. CA air is also different[/QUOTE]
SA Kid!!! California air is ONLY BAD, when Buster T. & I FART in UNISON SA Kdad
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12-15-2016, 01:57 PM | #17 |
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Re: some compression testing advice
Trying Burping and Farting at the same time Bill, it will cause a vacuum and not create
any smog saving our air. Thanks |
12-15-2016, 03:54 PM | #18 |
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Re: some compression testing advice
Thanks to all the barners who took time out to reply. Will run it for a while Saturday outside, just to cold out there for me and Francis today...only 17. and real windy, afraid my top might blow off you know. Will keep in touch and thanks again Dutie
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