C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old Jul 20, 2008 | 12:44 PM
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Just Checked out a friend of mines 85..NO Power won't even get up my driveway....40-30 50 70 lbs on compression gauge..I checked the easy cylinders...It only runs a minute at a time then craps out...NO POWER...I told him engine timeAnd there's a knocking sound like they want to comein... Whatta you think
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Old Jul 20, 2008 | 12:53 PM
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With compression that low on numerous cylinders I'd say the cam chain/belt has jumped.
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Old Jul 20, 2008 | 01:11 PM
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Originally Posted by 65Z01
With compression that low on numerous cylinders I'd say the cam chain/belt has jumped.
i agree it has to be valve timing. However I would doulble check that guage and make sure the schrader valve, if it has one inside the adapter is out. Check it on any other car you have to make sure the guage is good. It cannot have that many bad cylinders at once. If the cam timing is off by virtue of a bad timing chain you will get those numbers. 1 tooth is enough.
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Old Jul 20, 2008 | 01:29 PM
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Didn't '85s have nylon covers over metal-tooth gear timing sets? Better drop the pan and clean out the debris too when you sort it out.
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Old Jul 20, 2008 | 01:33 PM
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So once I get the car in the garage ...I should check the timing ??Gears and Such..Not a problem That would be a good thing for my friend(cheap)
maybe with the amount of miles the chain streched..Could that make it not want to run for more than a few seconds and have no power...I'll go back out there and turn the distrib a little to see if I can Get it to run Longer ..At least into the garage,,,, It does bang though on start up big consern

Last edited by Happydad; Jul 20, 2008 at 01:42 PM.
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Old Jul 20, 2008 | 01:38 PM
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FIC Thanks..But its a Pretty good Compression Gauge and I took random readings..I wondered why it would not run or move under power..The engine noise has me concerned
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Old Jul 20, 2008 | 01:38 PM
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Base timing, not ignition timing. If base is off too far, you can have piston to valve contact. These are interferance motors.
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Old Jul 20, 2008 | 01:45 PM
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Interference means Bent Valves
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Old Jul 20, 2008 | 02:33 PM
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Thanks Guys At least I have a Starting Point
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Old Jul 20, 2008 | 07:34 PM
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The banging could be piston to valve or it could be a timing chain that is out of place enough to be hitting the front timing cover.
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Old Jul 20, 2008 | 08:45 PM
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Check the other 4 holes. If they are off like the 1st 4, it's the chain.
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