Did you install the oil check valve in the cylinder head before mounting the cam housing? The photo in post #58 shows it's not installed yet.libarra82 wrote: Wed Apr 15, 2026 10:15 pm The cylinder head is back on the car. Leaving the head out in the sun and putting the dowel pins in the freezer worked perfectly. The pins slid in easily with thumb pressure, and a few light taps with a rubber mallet ensured they seated fully.
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Cylinder Head rebuilt recommendations
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michaelmount123
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Good eye, I did look into that when I was putting it back together. I checked the pictures I took when I disassembled it, and that port looks exactly the same. I know there are different check valves, and I assumed this was the permanent one that has to be drilled out for removal. There does appear to be something in there, but it isn’t visible from that angle in the image.
It would be really helpful if we can figure this out.
It would be really helpful if we can figure this out.
I started the car and the engine runs and sounds great. There’s a lot of smoke coming from the exhaust manifold.
I’ve read that this can be normal and may just be oils burning off from the install, but I’m still pretty nervous. I can’t bring myself to let it run for more than a few minutes at a time.
I’ve read that this can be normal and may just be oils burning off from the install, but I’m still pretty nervous. I can’t bring myself to let it run for more than a few minutes at a time.
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michaelmount123
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Don't fret; all is okay!
That check valve should be there, but it can probably wait until you get around to it. It's purpose is to keep oil in the cam housing so the lifters don't clatter on start-up. Without it, the cam housing oil galley may drain back into the sump when the engine is off, then re-pressurize on start-up. No harm done. Your smoke is not related. It's common, and typically wayward oil that got in and on your exhaust during disassembly. It will burn off pretty quickly.
Your machine shop may have removed the valve to clean the oil passage, or perhaps it's been missing and you've run it that way. BTW, there's a TSB that describes the check valve removal and also recommends using a check valve from a 951 to replace it in the NA cars.
I didn't mean to cause any concern, but just noted that it appeared to be missing.
MM
That check valve should be there, but it can probably wait until you get around to it. It's purpose is to keep oil in the cam housing so the lifters don't clatter on start-up. Without it, the cam housing oil galley may drain back into the sump when the engine is off, then re-pressurize on start-up. No harm done. Your smoke is not related. It's common, and typically wayward oil that got in and on your exhaust during disassembly. It will burn off pretty quickly.
Your machine shop may have removed the valve to clean the oil passage, or perhaps it's been missing and you've run it that way. BTW, there's a TSB that describes the check valve removal and also recommends using a check valve from a 951 to replace it in the NA cars.
I didn't mean to cause any concern, but just noted that it appeared to be missing.
MM
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Tom
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I've never not had the header smoke after removing the head, no matter how careful I think I'm being. I usually burn it off with a few short sessions out of an abundance of fire caution -- heat it up enough to start smoking then shut it off and let it smoke off a bit, then rinse and repeat. Congrats on getting it running!
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michaelmount123
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Tom
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Thanks MM -- I have never seen that. What engines does it apply to? Does it apply to the '89 2.7 head?
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michaelmount123
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Hey Tom. The 2.7 cylinder head has a unique check valve. It’s a more sophisticated piece; probably expensive, but same simple one-way function.Tom wrote: Mon Apr 20, 2026 7:05 pmThanks MM -- I have never seen that. What engines does it apply to? Does it apply to the '89 2.7 head?