Captain Obvious

Wow. I didn't even see the air cleaner. No idea what that's all about. So I heard from my buddy at the auction that there were a couple bidders from Canada. Anyone we know here?

I give you pretty much zero chance of success trying to use just 13 of the 14 head bolts. Especially missing one right in the middle. You've simply got to get that bolt stub out. So you rebuilt the head and then the head bolt snapped when you were putting it back on? Did you know that the bolt had snapped then?

What is that? That's the way they designed it. The story I heard (read it on the internet) is that they increased the fuel capacity in 77 and they stole the extra volume from the spare tire well. And since the spare well is shallower, they had to use that false wooden floor. If you compare the floor sheet metal to earlier years, you'll also see the 77-78's have extra metal reinforcing "frame" members on the top side of the rear metal deck that didn't exist in earlier years.

HLS30-03981 with a 5/70 door jamb plate sold at auction not too far from me. Sold for $23.4K II know you guys like to talk about this kind of stuff. https://johncarlauctions.hibid.com/lot/54741878/1970-datsun-240z/?cpage=6&q=&ref=catalog A non-Z friend of mine was there because he was interested in the real estate property and he sent me the link.

LOL. Cliff in a library? This is what I picture:

I don't know anything about this stuff... What's a "smart coil"? Is that one that handles things like dwell and saturation current by itself? Sounds neat. Is there a test report on the web you can point us to?

So one of the closing items to bring up is that I did take some quick and dirty measurements on the valve protrusion while fully open, and according to the numbers, it's definitely an interference design. The valves stick down about .200 beyond the bottom of the head when they are fully open. I didn't spend a lot of time trying to max out the lift to the thousandth, so it's likely that it's a little more than this. I just eyeballed it as I turned the cam and set the cam where the lift was the greatest. Could be a little more than .200, but it's certainly no less: And my new (Nissan) head gasket is about .055 thick new (before any compression due to installation torque): So even if there is no crush on the head gasket thickness, the valves will stick down .145 beyond the bottom of the gasket. And considering the .115 dish depth on the pistons, it's an interference design. I've got some other closing items to document as I get the time. Things like my flying trapeze head lifting rig that worked out fantastic...

Yeah, definitely a labor of love to put that amount of work into the lowly stock N47. But as you suggested, it was personal. Me against my PO. LOL! Have to give it some time to wait for potential issues to surface, but I believe I won.

Thank you. Appreciate the well wishes! It's going to take some time for me to regain confidence in the motor. Now I have to finish pulling that F54 block.......

I think you're right. I think it will have some tiny impact on the compression and performance numbers as well. But I'm only off by .003 on the intakes and .001 on the exhausts. I'm pretty sure that I'm leaving a tiny bit of performance on the table, but for the first batch of miles, I'm willing to take that tradeoff for the piece of mind. Of course, I'm not an expert on the topic, but that's what I'm thinking! Maybe I just need a padded cell:

It's alive!!!!!!! I ran a compression test before I started it (so it was stone cold) and the highest cylinder was 175 and the lowest was 160. The max differential between any two adjacent cylinders was 10 psi. After all the crap I found wrong done to that engine, I'm pretty happy with that. I have all the valves set a little loose because I'm thinking they might tighten up a little bit over the first batch of miles as everything beds in. I don't want any of them hanging open, so I set all of them (intakes and exhaust) to .011 cold. The plug into the water jacket seems to be holding, and it sure is nice to be able to tighten down all the bolts on the valve cover down and have it not seep oil. That's a new one for me with this car! Might just be wishful thinking, but my oil pressure seems a little higher. I'm thinking that since it's not gushing out the seam between the cam tower bearing and the head anymore and actually feeding the cam bearing. @jonathanrussell the cam seems to be quite happy in it's new home!!! So far, so good! I'm gonna drive it for a couple days and then give everything a once over to see how it's doing. Pull the valve cover and see if I'm wiping any lobes off. Check the lash. Change the oil. Do another compression test. I forgot to pick up new plugs too, so I reused the old ones. I'll pull them and see how they look, but I'm not sure it'll be an accurate representation. I'll replace them soon. So, about the only thing that I'm worried about is I don't think the exhaust header is sealing properly. Stupid header. Not sure if it's a gasket quality issue, or a header quality issue. My copper nuts worked out great, but didn't make it seal.

Haha! I got no problem with that! As good as it looks, try to keep it that way! Piece of wood between the jack and the foam pad and it'll last for a little while.

Thanks for the additional clarification and I'm really sorry, but I'm still not sure I'm getting it. Is this right? You had the engine rebuilt 600 miles ago and everything seemed perfect including the oil pressure. Then 100 miles ago, all of a sudden, your oil pressure (as indicated on the dash gauge) shot up. But other than the oil pressure, nothing else seemed wrong. Then just a day or two ago, while investigating the high oil pressure, it started smoking badly and that's when you pulled the head. Did I get it that time? I feel so dense. If I don't get it this time, I'm going to just keep my mouth shut and stay completely out of it!

Valve stem seals and/or guides have no effect on oil pressure. Can have impact on consumption, but not on pressure. So just to make sure I understand the issue.... Car had been running great. No problems. Then one day, all of a sudden your oil pressure started running way higher than it used to, and you started blowing blue smoke?

Looks great. But whatever process you're using to install new bushings, I think you should get the coating out of the bushing holes first. Even if you're using a hydraulic press.

Bummer. So how long until you're back and have a Z?

Don't weld anything shut. Just use a threaded plug. You never know if you'll want that O2 bung some time in the future. Yeah, all the bits and pieces add up. Good luck with the project!

Well that might explain the square headlight mods that have popped up here a couple times. Evel Knievel started that trend maybe?

Awesome. Glad to hear your bush is still fixed!

Gotcha. Well I don't have any idea if the two manifolds flow the same, but I "try" to believe that the later manifolds are the same or better than the earlier ones. One thing to think about is that by the time you get to the rear part of the manifold, you're only feeding one cylinder, so maybe the fact that the ZX version tapers down at the rear doesn't have much impact. Or... Maybe it just makes the bean counters happy because it lowers the car's weight ant takes less aluminum to produce. Maybe that's why it's "better". Not being an expert at all in the field, my gut tells me that you won't notice any change one way or the other. My non-expert advice is to use the one you think looks better. At the performance level of these engines, I doubt there's much performance impact. So does your 80 ECU use an oxygen sensor? That hadn't been incorporated yet, had it?

So I double checked my measurements on the 77 and 83 throttle bodies, and they're the same ID. They are both 2 in. ID. 77 throttle body: 83 throttle body: The only significant difference I could find was the OD of the input side. 77 OD on the inlet is 2.35 inches OD and the 83 OD on the inlet side is 2.20 inches OD. So the original 77 ducting would be too big, but the inside diameter is the same. I also re-checked the mounting holes, and they are in the same spots. No difference there. And I didn't take any measurements on the location of the throttle linkages, but to the naked eye, they look the same. 77 on left, 83 on right:

Glad to help. Here's some pics. This is all the parts for the power valve: And here's a close-up of the washers in question: Here's the parts assembled on the sealing bolt sans diaphragm. The diaphragm goes between the two large washers: Good luck!!

@Reptoid Overlords, do you have all the ZX parts including the wiring harness and ECU? Or just the mechanical stuff? I wouldn't assume that the ZX intake manifold "has capacity to move a higher volume of air". In fact, might be a fallacy, but I would like to believe that the years of additional research, testing, and development would result in improvements in the overall design. Other than the lack of EGR, what is it about the 76 intake manifold that piqued your interest? My car is a 77, and the ZX system I have is from 83. A whole lot happened in the world of technology in those six years. Might be wishful thinking, but I would hope that the 83 system is "better"? Possibly? Maybe?

I measured them yesterday and I do not believe this is incorrect. I believe they are the same size. I'll check again if I get the chance today to confirm for positive sure.

What he said. There are two completely separate (identical?) disks. I'll see if I can get a pic of the parts and post them.