ETI4K

There was zero leakage of oil or antifreeze. I am certain the pitting and gouges are from debris. The pump gears are hard, but not like tool steel. A file scratches them. So, I finally got to measure the head today. Got in onto the bench and was rolling it into position and guess what I saw? Metal filings and glass beads in a water passage. Interestingly, the same machine shop did the work back in '96. Maybe cleaning after milling ain't a happening thing. I didn't find any metal in the oil pan, but definitely hard, rough, very small particles. Also, when I built this motor I capped it off with a polished valve cover from MSA. My search for the source of debris turned up a problem with that valve cover. The vent baffle perimeter is sealed with a material that is extremely hard (probably started as firm and flexible). I found several pieces of that sealant in the debris field. The pieces are quite brittle. If some of these made their way through the motor, I could easily see them causing this damage. If that is true, then any valve cover is essentially a time bomb. As if there aren't enough things to keep us awake at night. 🤯 Oh yeah, measured the head. It's been cut a total of .106" with .007 off the top (machine shop just did it) and the balance off the bottom. Combustion chamber now measures 43.5cc.

Anyone notice the debris at the water pump cavity in the TIMING COVER 😉? Or at the exhaust ports? How about these pics of what was a brand new oil pump... Truly, now a wasted pump. Some serious debris has been through this motor. Why did the oil filter not catch it? Perhaps bc it went into bypass during winter starts and that 5hit went right on through to ruin the oil pump, timing cover, cam towers, and score the cam and crank journals. Maybe more. What I've not commented upon is the fine grit I found in the oil pan. I've spent a lot of time reflecting on what was going on at that time in my life ('96 - '97) to try to understand what might have happened. I've considered my negligence or oversight by allowing debris in the area while building this motor, machine shop debris left in passages (again, my oversight for not clearing it), sabotage by employees (I had received several serious threats), contaminated oil and antifreeze (IMPOSSIBLE), and so on. My principal concern is to avoid it happening again! The cost to have the original machine work done was painful then, now it'll be much worse. More later...

@siteunseen The exhaust seats show some good pitting (I'lltry to get some pics). These were cut clean with a 3-angle finish way back when. They may clean up with a valve job. I suspect the time on the engine stand had something to do with it but that's really just WAGuessing. I have never seen pitting this bad before.

Wow, those are some tight tolerances. I've spent many, many days trying to figure out how to deal with total accumulated tolerances of .005" from about a dozen parts. Ahh, the good ole days. They were fun, and yet, I'm sure glad it's not mine to worry over anymore.

Even putting it into words is dangerous man. What happens if she figures out your password? 😳

Yeah - .0015 - .0020 interference. The coefficients of expansion are ~12.5 for aluminum and ~9.76 for bronze. If the towers see a temperature change of 120F (bearings made at 80F, engine warms to 200F), then the bore in the towers would increase from 2.0400 (1.8898 + bearing wall thickness of .075) to 2.0431. The bearing OD would change from 2.0415 (2.0400 + .0015) to 2.0439, so still an interference of about 8 tenths. I'm beginning to like @madkaw's suggestion of sourcing another head.

Well, of course you are correct. I know that, but somehow my feeble mind typed it out anyway. Yes, I'm a nimrod. I haven't seen the crank and I too can't see how the scratches would clean up by polishing. I got that info from the shop owner, not the guy who did it, so we'll see. Cutting it again wouldn't be the end of the world. Anyway, I plan to mic the head tomorrow or Thu. More to tell then

Hey! I'm trying to enjoy my cocktail here!

Always open to ideas and changing my plans accordingly, though sourcing another head in decent condition sounds iffy. The only bit that my head has me concerned about is the water pump cavity. It will certainly reduce pump efficiency. I know there are epoxies that are up to the task of repairing it, but I'm not keen on that idea. It could be welded and machined back, and I could do that, though it is certainly a non-trivial undertaking.

My machine shop still has the motor (since January). No rush on my end. The good news is the cylinders were not scored, the crank journals polished out okay, the cam polished out withing spec, and the pistons are okay. Unfortunately the towers did not fair so well. Three of them are out of spec by .003 and each is a different size. There is also some question that I am still trying to get to the bottom of, but it may be that the head was cut more than .080. Like maybe another .028. The problem is the towers were only shimmed .080. Adding to that, the head needs three guides, and the exhaust valve seats are beat up pretty well, so a real valve job is needed. So, in reply to @Derekquestion, I figured if the head is in for that much work, I'd prefer to have everything to spec and nice and tight. I can make the bearings and install them so that saves me a few hundred dollars (the machine shop in OH told me making them would be a T&M job - so that's a guess). I am familiar with the pain off trying to shoot that hone in the right direction, though I have never done it. I think the guy quoted me less than $200 to do that work only.

Well, that was the top side. Now the bottom side. The journals are not terrible but they had been polished. I am not sure what the debris is on the pick-up screen, but I did save it. At some point I will clean it of oil and examine it closely, just for edification if nothing else.

Then the pistons. I knew the rings didn't seat, but that's a lot of oil. I only ever saw blue smoke on shifts. No more than 15,000 miles.

The first issue I found was the headers had developed leaks. Not really surprising, and no real problem as I am replacing these with Sean Dezart's. Look closely though at the exhaust runners, then look at the water pump cavity and the scoring of the material.

And so it begins

I decided to start this thread to provide some background on some of the work I am doing/planning. My car is an early production 76. Back in 95, at the advice of Z Doc (Roanoke), I swapped motors from an 83 ZX, with the .080 head cut, early 280 valves, etc. and not much else in terms of performance. The car ran well, but not as well as I imagined it would, and it was okay. After a year or so and about 10-15K miles of daily use, I could no longer live with the rust, so I took the car off the road for a complete restoration. As life would have it, my plans got side-tracked. I started a business and never had the time to restart the Z project until now. So I went into this project knowing I had a good motor. Figured I'd disassemble and clean it, new gaskets and seals, have the cylinders honed and replace the chrome-moly rings with Total Seal (the rings never seated well). Well, to my utter surprise and disappointment, what I found was not what I was expecting.

@madkawI decided to start a thread for this project to explain some of the work I am planning. I will reply to your question there. It's titled: Another Z to see the roads again... @DerekThanks for that input. My concern is that used towers are unknown quality/condition. New bearings and bored to specification, assuming it is done properly eliminates any problem of a loose bore (loss of oil pressure, flexing of the cam, maybe loose engine noise which I hate). More on the other thread.

I'll reach out to him and see what he says. Thanks

Due to excessive wear of the bores in the cam towers, I am in the process of making and inserting bronze bearing inserts. So far, my search for a machine shop capable of align boring them has turned up one shop in Ohio, JCM Machine and Coatings. I am in Virginia. Though I have done it before, I am not delighted by the idea of shipping my head off somewhere. I'd much rather see their operation, look the man in the eye, and so on. Does anyone know of a shop that can do this work (and do it brilliantly!) - anywhere, but local would be ideal?

Indeed, I am replacing my floors now. I have been rereading the entire section and have been taking notes to copy some of your ideas - like scoring the metal to facilitate bending of your frame connectors and adding a jack plate for starters. Thank you again for taking the time to provide so much helpful information - especially what the original sheet metal looked like!

Exactly. I have a very long history of missing badly when estimating how long something will take, so I'm keeping my mouth shut on that one. I used to believe I'd get it done in a couple of years. Then I read Mark's thread! 😉

I'm basically starting my journey; I'm in only a couple of weeks. My wife has asked several times already, "So how long do you think it will take?" She clearly has plans. Meanwhile, I'm fitting the garage with a hammock....

What an amazing journey. Can't wait to hear it...need audio of a few fly-bys!

I've never been too impressed by someone who shows up at a car show with a brand new car. Just doesn't seem to demonstrate any problem-solving abilities or particular skill set - aside from being able to make enough money to write a check, which is one skill I've never mastered, damn it! 😪

Hope the weather was as gorgeous for you as we enjoyed here in VA. It's great you got to go out and do something fun. I spent the day tacking in a new floor pan on the passenger side (driver side next). It's on a rotisserie and that makes it easier, but I'll swear I made 1,043 trips around that car making damn sure every tack location was perfect. Wore me out. I think if the car had been on its wheels, it would have killed me.

Wow, haven't heard Golden Earring in a long time. My favorite time was back in 94. Three years earlier I had leased a VW Corrado and my wife was driving a 300ZX Turbo. We had lots of fun racing each other over those years, er, I meant to say touring together. I actually call that spirited driving Bumper Tag. Anyway, I was returning the Corrado at the end of the lease, and my wife was in her car to bring me home. The inevitable who can get there first started. Shortly after the START, Radar Love came on the radio - my all-time favorite driving song. As I pulled into the dealership and stopped, the song ended and I turned off the engine. It was an absolutely perfect moment. I got out and walked away, smelling hot brakes, listening to the engine crackling as it cooled, and smiled at my wife - because I beat her! 🥳