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65 Corvette 327 ci, 350 hp


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vfoltz
Novice

Apr 11, 2010, 3:05 PM

Post #1 of 20 (4772 views)
65 Corvette 327 ci, 350 hp Sign In

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?


re-tired
Veteran / Moderator
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Apr 11, 2010, 3:46 PM

Post #2 of 20 (4769 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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


vfoltz
Novice

Apr 11, 2010, 5:49 PM

Post #3 of 20 (4763 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

I have a compressor. How much pressure should I apply to each cylinder?


fordtech
User

Apr 11, 2010, 5:59 PM

Post #4 of 20 (4762 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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.


re-tired
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Apr 11, 2010, 6:55 PM

Post #5 of 20 (4758 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

Most home compressors go to 100 psi + - . That is more than enough.


LIFE'S SHORT GO FISH


Sidom
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Apr 11, 2010, 7:26 PM

Post #6 of 20 (4757 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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.........


vfoltz
Novice

Apr 12, 2010, 5:38 PM

Post #7 of 20 (4746 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

The 1965 was the last year with no PCV valve.


vfoltz
Novice

Apr 12, 2010, 5:42 PM

Post #8 of 20 (4745 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 13, 2010, 12:13 AM

Post #9 of 20 (4742 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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



vfoltz
Novice

Apr 18, 2010, 9:26 AM

Post #10 of 20 (4721 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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?


vfoltz
Novice

Apr 18, 2010, 9:26 AM

Post #11 of 20 (4720 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 18, 2010, 12:30 PM

Post #12 of 20 (4718 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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



re-tired
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Apr 18, 2010, 12:40 PM

Post #13 of 20 (4710 views)
Re: 65 Corvette 327 ci, 350 hp Sign In


In Reply To
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.


My thoughts eggzackly.Like minds think alike TOM.


LIFE'S SHORT GO FISH


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 18, 2010, 12:45 PM

Post #14 of 20 (4709 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

">>My thoughts eggzackly.Like minds think alike TOM. <<"

Still crazy after all these yearsCrazy


T



vfoltz
Novice

Apr 25, 2010, 1:56 PM

Post #15 of 20 (4692 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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?


re-tired
Veteran / Moderator
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Apr 25, 2010, 2:29 PM

Post #16 of 20 (4685 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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


vfoltz
Novice

May 3, 2010, 4:19 PM

Post #17 of 20 (4664 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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?


re-tired
Veteran / Moderator
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May 3, 2010, 7:01 PM

Post #18 of 20 (4662 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

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


Tom Greenleaf
Ultimate Carjunky / Moderator
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May 4, 2010, 11:09 AM

Post #19 of 20 (4656 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

   ">>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 electricityCrazy

T



chickenhouse
Enthusiast

May 5, 2010, 4:21 PM

Post #20 of 20 (4642 views)
Re: 65 Corvette 327 ci, 350 hp Sign In

Even a blind chicken gets feed now & then!!






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