Need some help with new 383 issues

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Need some help with new 383 issues

Postby Fastmax32168 » Sat Dec 24, 2016 3:47 pm

I am pretty baffled by my current situation with this motor. I have a new 383 that is using oil at the rate of about 1 qt every 100 miles. And it struggles to idle. It is pretty mild with a Lingenfelter 213/219 duration camshaft on a 214 centerline and brand new vortec heads with about 9 to 1 compression, so I am thinking it should idle almost like a stocker.
1. It only pulls about 15 lbs of vacum at idle. I thought perhaps it had an internal intake leak but if I pull the PVC and idle it there is no air being sucked into the valve cover filler. I used a strip of paper by the hole to test it. Yes I have checked everywhere for an external vacum leak and cannot find one.
2. You never see it smoking which is puzzling, you would think it would look like a mosquito fogger using that much oil.
3. After about 1000 miles The plugs were nasty oil fouled and in every cylinder not just one. in addition they were all fouled only on one side of the electrode, the other side looked pretty clean. I figured valve seals or valves loose in the guides so today I replaced the valve seals on one side of the motor but I honestly didnt see anything wrong with the ones I took off so I will be surprised if it makes a difference. The valves did not seem loose in the guides.
4. I have made sure the PVC is working properly, and I see no oil in the PVC hose or the manifold. I am running stock GM valve covers with baffles.
5. Leakdown test only shows about 6% leakdown in the two cylinders I tested, and they were two with the nastiest looking plugs.
6. It has 180lbs of compression dead on after 3 pumps in every cylinder.
Suggestions anyone?
Thanks
Roy
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Re: Need some help with new 383 issues

Postby waybad » Sat Dec 24, 2016 4:58 pm

have your heads been milled at all? sound like the intake gasket is leaking on the lower intake valley side, when and if you pull the intake check the impression on the gasket, if your heads were milled you have to have the intake milled to get the ports back aligned up.. my 2cents? :shock:
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Re: Need some help with new 383 issues

Postby Fastmax32168 » Sat Dec 24, 2016 5:12 pm

Tinker the heads are new. One of my first thoughts was that the intake was leaking in the valley but wouldn't I be able to detect the air being sucked in the oil filler cap with the PVC disconnected? In the past I have tested for this by holding a strip of paper by the oil fill hole and the paper is not being drawn inward with the car idling.
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Re: Need some help with new 383 issues

Postby cjbiagi » Sat Dec 24, 2016 5:25 pm

I am tending to agree that it is a intake leak at the lower end of the manifold, this is exactly how it would act. Is it possible that at some point the intake manifold was cut? Is this a used intake? Are you sure you have the correct intake gasket? I am not familar with the differences on vortec heads, so maybe I am missing something there.
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Re: Need some help with new 383 issues

Postby Fastmax32168 » Sat Dec 24, 2016 6:01 pm

Clyde it was a used intake I have had for a while. I am getting the same feedback on the thirdgen board so I think I will pull it off and have a looksee. Not too big a job.
Roy
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Re: Need some help with new 383 issues

Postby waybad » Sat Dec 24, 2016 10:24 pm

Fastmax32168 wrote:Tinker the heads are new. One of my first thoughts was that the intake was leaking in the valley but wouldn't I be able to detect the air being sucked in the oil filler cap with the PVC disconnected? In the past I have tested for this by holding a strip of paper by the oil fill hole and the paper is not being drawn inward with the car idling.

I'm not sure,, but it sounds like a small enough leak that when Idling it may not draw enough suction to be a leak,, but when you have more rpm it draws more air and with more rpm, oil might be more in the heads running back down to the pan,(and splashing around the lifter valley), it's getting sucked in the leak then? if you have a vacuum gage, try revving it up to about 3500(real steady) with the gage on a manifold port and see if it stable? might give you a fluctuation if it has a leak.. worth a try before you pull the intake.. that's where they have always been with my troubles,, the heads might be new but the intake may not match good enough? good luck and be sure to tell us what you find..
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Re: Need some help with new 383 issues

Postby Monza Harry » Sun Dec 25, 2016 12:15 am

Roy your mention of one side of the plugs being oiled down has me thinking about oil ring gaps they may they have rolled around to alignment from the fresh crosshatch? That would be a number 2 check if your intake search yields nothing. Just trying to make the symptoms match my thought process, no actual personal experience with that though. Harry
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Re: Need some help with new 383 issues

Postby cosvega76 » Sun Dec 25, 2016 11:19 am

I agree about the intake. If it's pulling 15 inches of vacuum at idle, it isn't much of a leak. Since Vortec intakes only attach at the corners, there could be enough warpage to allow the intake ports to seep. Or, if the previous engine it was on was decked, the intake may have been cut to accommodate. What kind of gasket are you using? Fel-Pro makes gaskets with silicone beads, which may seal better than just fiber.

There is an easy way to check port alignment. Run strips of masking tape so the outside edges align with the upper and lower edges of the ports on both the heads and intake, with enough extending past the head and intake for viewing. Set the intake on the engine and see how closely the edges line up. If the edge of the bottom of the intake ports is too far below the bottom of the ports in the heads, that may be the issue.


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Re: Need some help with new 383 issues

Postby Fastmax32168 » Sun Dec 25, 2016 2:10 pm

Well I pulled the intake and I would have to say it looks suspicious but I don't find it definitive. There is no misalignment, but it does appear as though the gasket is not as compressed at the bottom of the port as it is at the top. The print-o-seal ridge at the top is smashed flat and the one at the bottom is not. I am going to put it back together with a thicker gasket and see what happens.
Roy
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Re: Need some help with new 383 issues

Postby Smiley » Tue Dec 27, 2016 12:25 am

what heads, intake manifold and gaskets were on it?

Fel-pro and GM offer newer style 5.7 Vortec gaskets with the metal ring to stop crushing. They will not fix a warped or angle milled intake manifold though.
89017465 intake gaskets on the right are the ones you want.
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Re: Need some help with new 383 issues

Postby Fastmax32168 » Fri Jan 20, 2017 8:37 am

Everyone who said it was intake gaskets gets a gold star! :th:
Roy
80 Monza GT 3500 only known one in existence
77 Monza Monster Mirage Finally painted!
94 Corvette Convertible LT-1 500+ HP
07 Honda Civic Wifey's Ride
83 Malibu Wagon 350 EFI "The Longroof"
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Re: Need some help with new 383 issues

Postby cjbiagi » Fri Jan 20, 2017 10:29 am

Glad to hear you got it fixed.....
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Re: Need some help with new 383 issues

Postby waybad » Fri Jan 20, 2017 11:15 am

woooohoooo!! nothing like a easy fix!! lol glad it running!!! :dance: :dance: :dance: :dance:
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