Compression/Leakdown High - Shop Says Rings, Others Say No?

[MarcZ]

I posted on ls1 tech about my compression test results after experiencing lots of oil consumption, some blue smoke on acceleration occasionally, etc, and no one thinks it's rings, only the shop believes so. I'm inclined to believe these people on the forums because some of them build engines for a living or have built several LT1's Just thought I'd get some more input from you guys as well. Because I'm confused,

The compression/leakdown test results are:
#8 - 235psi w/ 8%
#6 - 240psi w/ 5%
#4 - 230psi w/ 9%
#2 - 225psi w/ 5%
#7 - 235 psi w/ 7%
#5 - 245 psi w/ 8%
#3 - 230psi w. 8%
#1 - 240psi w/ 5%

Bore - 4.042
Stroke - 3.48
Deck Height - 0.025
head cc - 56
stock head gasket

top ring gap - .020 2nd - .018
oil ring data .030
piston to deck clearance - .025
Piston (in cc's) - 5
main bearing clearance .010
piston to wall clearance - 4.038
thrust clearance - .003

valve diameter intake - 1.94, exhaust - 1.50


Engine was rebuilt 36k ago. Had headgasket blow at 12k. At around 19k I discovered I was consuming 1 quart every 1,500 miles. This increased in the last 4-5 months to 1 quart every week of daily driving. BTW, I took it to a new shop for the leakdown test, I'm never going back to the original builder.

[Fastbird]

Is there a particularily oily plug or cylinder? Those compression and leakdown numbers are pretty good for a quart every 1500 miles.

[MarcZ]

It was a quart every 1,500 miles, it is now 1 quart every 150 miles. They said every plug and cylinder was oily.

[96LT1355Z28]

How oily is the inside of your intake, is it possible your pcv system is not working correctly? Bad valve seals maybe, just guessing here. Hows the engines vacuum?

[Fastbird]

Those compression and leakdown numbers are all within specs though. IIRC compression should be no greater than 20% betweenany two cylinders and leakdown should be no more than 12%. I'd start looking at valve seals and guides and at an internal intake manifold oil leak. Also double check that your pcv system is working and you're not building crankcase pressure. Just some thoughts.

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[chile]

I would also lean towards the valve seals and pcv. I would start with the pcv those usually consume more oil when bad.

[Chris]

I second that its probably in the upper end of the motor.

[97lt1camaro]

Possible intake gasket leak?

When the intake gasket on my truck went, i was burning just as much oil an had similar results for compression and leak down. Gasket had pulled into a port and was pulling oil in from the lifter galley.