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65 Corvette 327 ci, 350 hp
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vfoltz
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Apr 11, 2010, 3:05 PM
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65 Corvette 327 ci, 350 hp
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I am experiencing high pressure in my crankcase that is causing oil to go up the crankcase air intake and puddle at the carb. I checked my cylinder compression: Driver side: 180, 180, 175 and 179 Pass. side: 160, 160, 165 and 148 Chilton states 150 is required. What could be causing this high pressure in the crankcase?
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re-tired
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Apr 11, 2010, 3:46 PM
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Re: 65 Corvette 327 ci, 350 hp
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Do a wet/dry comp test.. You have done the dry test. Now take a pump style oil can and give each cyl several shots of motor oil. leave plugs out. crank eng over a few times . redo compression test . if any cyl has a big improvement it could have a small hole/crack or broken ring(s.) If you have a air compressor and adapter to put air into cyl you could put each cyl on its TDC and put air into it and find air leak. LIFE'S SHORT GO FISH
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vfoltz
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Apr 11, 2010, 5:49 PM
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Re: 65 Corvette 327 ci, 350 hp
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I have a compressor. How much pressure should I apply to each cylinder?
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fordtech
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Apr 11, 2010, 5:59 PM
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Re: 65 Corvette 327 ci, 350 hp
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do a wet test as rt recommended on the cyl. with the lower compression and see what the compression is and post on here with the results from that. as that is going to show as to where to go next in the diag.
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re-tired
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Apr 11, 2010, 6:55 PM
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Re: 65 Corvette 327 ci, 350 hp
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Most home compressors go to 100 psi + - . That is more than enough. LIFE'S SHORT GO FISH
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Sidom
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Apr 11, 2010, 7:26 PM
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Re: 65 Corvette 327 ci, 350 hp
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There is a some differences on your compression readings, you've good some good tips on tracing that down. You should also make sure your pcv valve is free and clear. A stuck valve can also give you some high pressures and force some oil into the air filter.........
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vfoltz
Novice
Apr 12, 2010, 5:38 PM
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Re: 65 Corvette 327 ci, 350 hp
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The 1965 was the last year with no PCV valve.
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vfoltz
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Apr 12, 2010, 5:42 PM
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Re: 65 Corvette 327 ci, 350 hp
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Is it normal to see such a big difference in one side of the engine to the other? I realize the 148 looks suspect, but the others are low compared to the drivers side.
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Tom Greenleaf
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Apr 13, 2010, 12:13 AM
Post #9 of 20
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Re: 65 Corvette 327 ci, 350 hp
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Note: Vette may have gotten away from it but I think all gasoline engined cars sold to the US in 1964 (model year) and newer had to have a PCV. Prior to that a vent tube just ran to the ground with a 'venturi' effect and vented fresh air in thru oil filler cap. If valve covers have deleted that it would sludge up. Just a note, T
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vfoltz
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Apr 18, 2010, 9:26 AM
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Re: 65 Corvette 327 ci, 350 hp
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After wet test: 2 dry: 160 wet: 172 4 dry: 160 wet: 160 6 dry: 165 wet: 180 8 dry: 148 wet: 155 What do you think?
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vfoltz
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Apr 18, 2010, 9:26 AM
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After wet test: 2 dry: 160 wet: 172 4 dry: 160 wet: 160 6 dry: 165 wet: 180 8 dry: 148 wet: 155 What do you think? If I was to install all of the spark plugs excluding one cylinder to see if the blow bi stops will that cause damage?
(This post was edited by vfoltz on Apr 18, 2010, 9:35 AM)
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Tom Greenleaf
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Apr 18, 2010, 12:30 PM
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Re: 65 Corvette 327 ci, 350 hp
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Smile - you can do that but it's damn noisy. Your #8 seems like a valve issue. How much does this engine get run? Some will do better with a good run but you have oil in wrong places so chase that first. Instead of running without a plug (ground that wire if tried) I'd try putting the cylinder(s) on TDC and apply air pressure and see where it comes out - intake, exhaust or just remove dipstick and see if it blows out there or oil fill cap. Make sure you are in neutral as if piston moves the car can if standard. Is crankcase ventilated at all in this? T
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Tom Greenleaf
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Apr 18, 2010, 12:45 PM
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Re: 65 Corvette 327 ci, 350 hp
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">>My thoughts eggzackly.Like minds think alike TOM. <<" Still crazy after all these years T
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vfoltz
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Apr 25, 2010, 1:56 PM
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OK. Just completed a test on each cylinder at 50 psi. All but one have air coming from crankcase and not intake / exhaust. Could it be my valve seals leaking and letting air pass into the valve cover back down the ports to the crankcase or do we think it is the rings?
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re-tired
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Apr 25, 2010, 2:29 PM
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Re: 65 Corvette 327 ci, 350 hp
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It is highly improbable that volume of air is goiing past the valve seals. If test was done correctly I would say worn rings/cyl walls LIFE'S SHORT GO FISH
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vfoltz
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May 3, 2010, 4:19 PM
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Re: 65 Corvette 327 ci, 350 hp
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Brought the car back to the shop who performed the engine rebuild 3 years ago. They found the problem to be the crankcase ventilation bypass valve under the intake manifold. What do you think?
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re-tired
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May 3, 2010, 7:01 PM
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They have the eng in front of them I do not . THe only question I can raise is this :When doing the air pressure test air is put into the combustion area. Both valves are closed. Air pressure should not be going anywhere including intake, but, air IS going into the crankcase. But its their eng job . Give them the opportunity to prove themselves . I HAVE guessed wrong a few times in the past . Yes yes I know it's hard to believe . But even a monkey can fall out of a tree now and then. LIFE'S SHORT GO FISH
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Tom Greenleaf
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May 4, 2010, 11:09 AM
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Re: 65 Corvette 327 ci, 350 hp
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">>I HAVE guessed wrong a few times in the past . Yes yes I know it's hard to believe .<<" WHAT! Impossible - that had to pre-date electricity T
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chickenhouse
Enthusiast
May 5, 2010, 4:21 PM
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Re: 65 Corvette 327 ci, 350 hp
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Even a blind chicken gets feed now & then!!
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