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Beastlikethat1

L28 Burning Oil

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Just recently had my head rebuilt on my 1978 280z. Only down side is I'm at low compression across all cylinders and even lower on one than the others 😒.  Does anyone have experience with an at home piston rings replacement? Would it be more worth it to just find a good used block/ whole engine? And is there anyone wanting to sell a l28 or l28e?

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9 minutes ago, banzai510(hainz) said:

make sure valve lash is not tight.esp on the one with real low compression.

Here in Washington Lmotors are pretty cheap. But your in Kentucky which might be harder

I'll be sure to check that out, I adjusted the valves not too long ago but maybe it's that. And I only seem to ever see l24's and on eBay people want $1,000+ for a 100,000+ mile engine!?

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170 or better would be good but depends on the compression ratio. 150 is still ok, 130 is worry some below, 120 is nearing rebuild time. As long as all are fairly even across it will run and idle smooth but if burning oil...

 

A leak down test will help spot where the compression is leaking out. If you listen at the intake and hear hissing then the intake valves, if at exhaust pipe then the exhaust valves not sealing. If at the valve cover breather compression is getting past worn rings.

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Like Hainz said check the valve lash, maybe one valve not shut tight. Lapping or replacing a valve is easier/cheaper than rings. It's even possible the head was poorly worked on. Seats can come loose.

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Well it was a machinist and I that worked on it and I polished the valves and put the new seals on. I did feel as though the new seals we're kind of "sketchy" as in some of thoughs little C clips just didn't feel as tight as they should. That would be a good place to start too. 

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Seals can easily be changed with the head on but have no effect on the compression only oil control.

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