240z Valve Train Tapping After Head Work - VIDEOS Inside

[madkaw]

I remember reading your thread and was confused by the build. You say that replacing seats would be too costly but than a few lines down you said you replaced with new seats. Maybe you meant guides.

If you didn't replace seats then you probably will continue to have issues. Should have spent the money for steel seats , sorry to say. Those original seats are probably about ready to fall out- mine were.

Sorry to hear this news. Hope you figure it out.

[siteunseen]

My E31 had bronze seats, I posted a picture and got a reply from Blue.  I had a problem and didn't even know it.  Thanks Blue, they're being replaced now. 

 

[Diseazd]

Valve seats shouldn't be that expensive to replace. The seats are $60.00 ($5.00 each) and my machine shop charges $15.00 each (labor to replace). A couple hundred bucks for updating an engine to today's standards is worth the extra money. If your guy wants $75.00 each, I'd find another machine shop. But, that still doesn't answer the noise question. Did they reuse the old rockers? If so, did they reinstall the rockers and lash pads in the order they came out? If not, that could contribute to some of the noise. Check to make sure on TDC compression stroke that your cam sprocket timing mark is dead on ( I'm sure you've already done this). 2nd, back off your ignition timing a little (while it's running).....too much advance seems to make a valve train a little noisy.......see if you can hear it quiet down a little on retarding. I never have found that setting valve clearances hot or cold makes much difference in noise level, but some here have, so give that a try. Finally, Datsun engines are inherently a little noisy, especially when you are listening for every little possible demon. If everything checks out, and you have double checked everything (including oil pressure), run the thing as Is. It certainly sounds like it's running good......maybe all the old parts will break in over time and she'll quiet down. It certainly is a beautiful engine.....you've done a hell of a nice job in putting her together.

[madkaw]

I'm with Dizeased here. Seats are a bit of a job, but brass seats are soft enough to get out easy. Usually most people go bigger so it's a matter of over sizing the hole . Hardened seats are another story.

I also agree that cold and hot tolerances shouldn't make a big difference in the noise department.

[Hardway]

I got up this morning and let the Z warm up, letting it idle around 2K rpm to keep the oil pressure up.  Oil pressure was great, the temp went to the half way mark and then came down a little indicating the thermostat had opened.  Everything looked good, no leaks, and throttle response was good.  I let it go for a few more minutes before turning it off and quickly got the valve cover off.  I went through the hot lash settings as indicated above, .010 for intake and .012 for exhaust.  I had a few valves that needed just a little tweaking to get the right about of drag on the feeler gauge.  I put everything back together, started her up, and the tapping is still there.  It does seem to run a little smoother but that might be my imagination.  I recorded the video below and I firmly believe the tapping is coming from the rear half of the engine.  Using my mechanics stethoscope, with the car idling at 900 rpm, I was on the passenger side of the block placing the lead in between to humps on the head.  At the front of the head the sound was pretty normal, just sounded like gears turning.  When I moved to the rear of the head I could hear the same gear turning sound but additionally could hear the tapping.  It sounded like tapping your finger nail on a glass.  I think the next step is a call to the machine shop and get the guy’s opinion.  Part of me is already bracing for the possibility of having to pull the head back off.

 

[Zed Head]

Your latest video requires a sign-in.

 

You might try disabling each cylinder to see if you can narrow it down.  I don't know if piston slap noise is combustion dependent, rocker noise probably isn't, but since you don't know for sure it might give a clue.  Remove plug wires, one at a time.  Make sure you ground them to the block though, some ignition systems don't like to have their spark path jammed.

 

If you really wanted to go deeper, you could remove sets of rocker arms.  Lots of work but if its rocker arm noise, it will tell the story.  If the piston is down, you remove the arms with a screwdriver, by prying the valve down.  It's described in the How To Modify book.  I've done it on a head off the block.  Pretty easy.  Easier than removing the head, and looking for something that has no identity.

[Hardway]

Your latest video requires a sign-in.

 

I just published it.  It should not ask for a login now.

[gundee]

 

If you really wanted to go deeper, you could remove sets of rocker arms.  Lots of work but if its rocker arm noise, it will tell the story.  If the piston is down, you remove the arms with a screwdriver, by prying the valve down.  It's described in the How To Modify book.  I've done it on a head off the block.  Pretty easy.  Easier than removing the head, and looking for something that has no identity.

 

If it were mine and it had not been done, next I would remove the rocker arms and install all new lash pads.

I have done this before too with head on car.

Then re-adjust valves. 

I hate adjusting hot. Gave that up 20 years ago. Cold only for me.

[bartsscooterservice]

Did you replace the rocker arms/camshaft or just re-installed after the head work ? Big chance you need to change those 2, they are worn in on each other. In the picture below the arrow points to the place that makes the noise.

 

[siteunseen]

Did you replace the rocker arms/camshaft or just re-installed after the head work ? Big chance you need to change those 2, they are worn in on each other. In the picture below the arrow points to the place that makes the noise.

 

Has that head been bead blasted?  I want to do mine with glass bead and have it look like that.

 

Thanks,

Cliff

[Hardway]

Did you replace the rocker arms/camshaft or just re-installed after the head work ? Big chance you need to change those 2, they are worn in on each other. In the picture below the arrow points to the place that makes the noise.

 

For some reason your picture is not loading Bart.  Can you try re-posting it?

[bartsscooterservice]

I can see it. Try F5 a few times ?