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04-13-2019, 08:45 PM | #41 |
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Re: 40 V8 compression change all cylinders same time
New stock camshaft purchased from well known southern Ohio supplier.
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04-13-2019, 08:46 PM | #42 |
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Re: 40 V8 compression change all cylinders same time
Ran good for 2,000 miles. All valve parts are new from well known southern Ohio supplier.
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04-13-2019, 08:49 PM | #43 |
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Re: 40 V8 compression change all cylinders same time
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04-13-2019, 08:53 PM | #44 |
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Re: 40 V8 compression change all cylinders same time
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04-13-2019, 09:07 PM | #45 |
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Re: 40 V8 compression change all cylinders same time
Not if the degradation is due to burnt valves. Run them too tight and they will burn. Not having an engine open currently to check your adjustment technique, frankly I don't know if it is valid. I do know that is not going to put you directly on the heel of the cam. You mention your engine was built. When assembled, who adjusted the valves initially? Was it you with the method you have described?
Last edited by Russ/40; 04-13-2019 at 09:19 PM. |
04-13-2019, 09:25 PM | #46 |
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Re: 40 V8 compression change all cylinders same time
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04-13-2019, 09:57 PM | #47 | |
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Re: 40 V8 compression change all cylinders same time
Quote:
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04-13-2019, 10:01 PM | #48 |
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Re: 40 V8 compression change all cylinders same time
Burnt valves could be the answer, but would all the cylinders react the exact same way going from 100 to 65 at the same exact time? I have only used straight gasoline in the car since the rebuild.
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04-13-2019, 10:09 PM | #49 |
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Re: 40 V8 compression change all cylinders same time
I have the intake off now. This week if nothing new comes up I plan on taking one of the heads off and checking the valves to see if any show signs of damage. I have the tools needed to take the valves out.
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04-13-2019, 11:37 PM | #50 |
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Re: 40 V8 compression change all cylinders same time
before you take anything apart, do a cylinder leak test to see where the compression is going. if you dont have the fancy tool, i dont, you just weld an air fitting to an old spark plug, screw it in, get that cylinder to TDC and put low pressure, like 20lbs to it and listen. air out the carb=intake valve. air out the exhaust pipe=exhaust valve, and air out the oil fill/breather cap=rings. if you get all the same valves, i would suspect cam timing. this one is a puzzler!
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04-14-2019, 12:10 AM | #51 | |
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Re: 40 V8 compression change all cylinders same time
Quote:
It would be very weird or highly coincidentally that every cylinder went from 100 to 65 in a yr. Might need to take the intake off. |
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04-14-2019, 10:56 AM | #52 | |
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Re: 40 V8 compression change all cylinders same time
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04-14-2019, 11:15 AM | #53 |
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Re: 40 V8 compression change all cylinders same time
Leak down test sounds like a good idea to me.
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04-14-2019, 11:54 AM | #54 |
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Re: 40 V8 compression change all cylinders same time
I agree, the leakdown test is spot on. Wise move indeed.
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04-14-2019, 05:23 PM | #55 |
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Re: 40 V8 compression change all cylinders same time
[QUOTE=Craig CT;1746053]Hi L78CHEVELLE; If it's a faulty compression gauge that will take you back to carburetor and or ignition, Craig.
Hi L78CHEVELLE; I'd make sure it's not a faulty compression gauge before I took anything else apart. Good luck, Craig.
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04-14-2019, 07:53 PM | #56 |
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Re: 40 V8 compression change all cylinders same time
Post your procedure for compression testing when you try new compression gauge etc Something might be different which might give us a clue to why compression drop across all cylinders. Mike
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04-14-2019, 08:58 PM | #57 |
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Re: 40 V8 compression change all cylinders same time
I used another compression gauge and got the same readings on each cylinder. Will try the leak down with air on each cylinder as soon as I can get the tool. I will post the results.
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04-14-2019, 09:12 PM | #58 |
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Re: 40 V8 compression change all cylinders same time
I think everyone should be aware that the O/P said the engine started running poorly and when he checked the compression was down uniformly. I think that points to something more serious than bad testing technique or a bad compression gauge. The leakdown test sounds like the next best test.
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04-14-2019, 09:15 PM | #59 |
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Re: 40 V8 compression change all cylinders same time
i will mention this also, TDC on compression stroke, and if you are not right on top dead, some times the air will cause the crank to turn so keep your hands-fingers-trouble light cords-or cat away from the fan. good luck let us know what you find
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04-16-2019, 10:58 AM | #60 |
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Re: 40 V8 compression change all cylinders same time
Just curious about compression testing procedure. If throttle is not full open, will compression numbers be lower than at full open? Thanks. Mike
Never mind. OP is testing with intake off. CRAFT. Sigh. M Last edited by Mike in AZ; 04-16-2019 at 11:06 AM. |
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