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Reviving #5837.

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So I've been tearing down that head.  I pulled out all the valves and it's a good thing too, there was a ton of dirt in the springs, even after I soaked the whole thing in a bucket.  20190403_214822.thumb.jpg.c255cfa0fdfce3812790396ed9c43f58.jpg20190405_222321.thumb.jpg.1c29f2f1d22e1dff55b9c9c759de4293.jpg20190405_222313.thumb.jpg.9f4e770cb39ecd28364f9ab702d12503.jpg


When I inspected the valves there was some scoring or almost corrosion I didn't like, so I lapped the valves and that  cleaned those up nicely. 



Then I put them all back together with the springs and washers after it was all cleaned up nicely.



I installed new Viton seals and pressed them all down to seat with a socket. of course bathing everything in clean oil for assembly.



The springs and valves look much cleaner.



Next I pulled the Cam and towers from the N47 and put them on. I had to move the little pins to the new head but that was easy. 


All the rockers and caps fit perfectly. it looks like the cam lash is still set good too. I'll adjust it after it's running.








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Now that the head is done, I figured it'd be good to start on the block to see if there's anything I can find wrong there that would cause the low compression in cylinder 1. 


I drained and dropped the pan, the oil was nasty. I could see they'd rebuilt it relatively recently, but I doubt they ever changed the oil. it was black black, and really smelled nasty.  I looked at the bearings and they look almost new, no wear through the zinc coating.  I still need to plastigauge it but the crank looks great.


I pulled out the pistons and the oil passages are clogged and the oiler ring is caked with crud. all that is easy to clean, and I have new rings for it, but what's bad is the piston for cylinder 1 has a big ol crack in it. the crack stick out maybe 1/8 in but it doesn't look like it affected the block.  I will definitely have to replace the piston.


The main bearings also look new so I think someone rebuilt the block, especially since you can still see hone marks in the cylinders.  It's possible that cracked piston is just sitting off enough that the rings were not seating properly.  it's hard to say.  I never took out the valves in the old head to see if they were burned.


In anycase, I'll replace the piston and put it all back together with new seals.




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 So I went out and got another Piston to replace that cracked one.



It's not bad looking at all,   I cleaned up my old pistons, and found that each was marked, proving that this engine had been rebuild previously as expected.




I got the new rings and followed the instructions for install,  on each of the pistons and then reinstalled them in the Block.


I torqued them down to the ~40 ftlb of torque that was noted here on the forum.  I then pulled the main bearings to check them for wear.  They too looked like they were new, so I really don't think there were many miles since they last rebuilt this engine.  The nasty nasty oil tells a story though.  I'd expect, they rebuilt it, and with the cracked piston, it wasn't seating the ring and blowing oil. So they likely just figured it was a bad engine and not worth changing the oil and drove it till the cylinder head failed and all but melted down.  It's the only explanation I can figure. These Pistons cleaned up well, but there was easily 3/16" of carbon deposits on them and all the oil passages were clogged. I cleared them with bailing wire and a small drill bit. there are marks  and scratches all over so I wouldn't be surprised if this is the 3rd or 4th rebuild.  


Anyhow the Pistons and bearings are all back in the block with new seals.  I'm waiting on new timing chain guides to arrive then I'll put together the front of the engine with new gaskets and proper timing.  I have that copper gasket sealer spray I'm going to use. it's supposed to be really good. .  I have a new tensioner, and a new chain, just to be sure.


I'm going to try to find engine paint in approximately the correct bluegreen that these are supposed to be painted, and repaint the block, then piece it all back together. .  I'll paint the pan and install it last. 



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