Captain Obvious

Well you're going to have to accept it because I'm not going to measure it. I like the small bore gauge in that video. I don't have one of those, but I should.

Thanks for the part numbers. I know the head gasket changed a whole bunch of times over the years, and I've heard that the final version of the gasket was actually supplied to Nissan by Stone. And from the pic you posted... Based on all the round holes for the head bolts, that looks like it. For comparison, here's the head gaskets I recently pulled from two motors. One is an aftermarket gasket pulled from my 77 - Has "BC380" stamped in it, which I believe is from Payen. The other is a Nissan genuine gasket pulled from my 83 - Has NISSAN 15A stamped in it. Here's the two side-by-side:

1) What he said. The mode flapper doors rarely form a totally perfect seal, even with new sealing foam. It's not unusual to get a tiny bit of air still flowing through the heater core even when the control in in the VENT position. 2) No, and no. With the stock system, the only way to get recirculated air is with the control in A/C or REC HEAT. When you switch it to VENT, it always uses fresh intake air instead of recirculated. And as for connecting the intake door actuator to the intake manifold... I didn't study things extensively, but I believe that's backwards. I believe when there is vacuum present on that actuator, it pulls the door to fresh intake. So the point is... Just disconnect and plug the vacuum line to that actuator and I think it will always pull recirculated. I think.

Cool. Neat find. based on the pin numbers and similar use in the schematics, I would concur that there are a lot of similarities. Good luck with the repair. Sounds like you're almost done!

All of the valves wiggle a little bit, but yes, I've found that the exhausts wiggle more than the intakes. I'm not going to measure them, because then I'd know. I did measure the lengths of all the exhaust valves though, and found one that was twenty thousandths shorter than the rest. No idea why it's like that, but that one did not make my set of the six best exhausts.

No. That's exactly what they would they expect me to do. What I'm doing instead kinda goes like this. Under magnification and with the use of some sharpie marks on the sealing surfaces, I've tried to match up the correct valve with the correct cylinder. And then after that, I'm lapping them to match the seats. For example... Here's one of the seats before I've done much of anything to it. The valve that WAS in this location wasn't even close to making contact on most of the seat. I managed to find one of the other exhaust valves that was pretty close. Here's what I'm starting with: Here's my handy-dandy valve lapping "tool". I use double back sticky tape to hold the valve to the "tool": Some 800 grit lapping compound: And I work the pair: until I have something like this. Smeared contact markings over the entire seal: Yes, there are still a few pits on the valve seat, but I'm not looking for perfection here. I'm just looking to be able to drive a little bit more on this engine until I finish the F54/P79. What I'm ending up with is 1000 times better than what I started with!!

Yup! I Got it! Haha!! So not that it really matters, but that's an AF (Audio Frequency) amp, not an op-amp. Good luck with the repairs. I paid my way through a couple years of college fixing audio-visual equipment. One of the things I learned is that 95% of all failures are blown output stages. Even if the problem does not appear to be a blown output, it might be anyway.

Snorkel.

When I'm using sealer, I almost always use a syringe to put it down. I've found that less is way better than more. Without getting into whether you should have used it at all (or not) on a head gasket, I think you used way too much. @Locke Glad to hear you're starting over. I'm needing a head gasket sets for my upcoming projects. What was the Stone number on that gasket set?

Yeah, I can't figure out what to make of this car. Strange mix of what looks completely new and other stuff that just doesn't look quite right. That's why I'm looking forward to a copious number of high quality pics.

Uhhhh.... That might make sense to someone, but I'm not one of them. Out of curiosity, do you have a datasheet for that part?

What he said. @Mike, The above post is setting off my spambot alarm.

@Mike, The above post is making my spambot sense is ringing loudly... Five posts to date, all of them are nonsense....

Three lids! One. Two. Three. Haha!!!

So my valves were indeed AFU. Based on the wear patterns, they were all mixed up, and most of them were not sealing properly. One of the exhausts (4E) was even bent a little and not sealing for squat!. And I can tell by looking at the wear patterns and carbon traces that it's been like that for quite some time. Probably since my PO messed with it. It definitely did NOT just happened when the cam snapped. Today's progress was I got all the exhaust valves sorted out. As best I could, I matched the correct valves to the correct cylinder and lapped them into place. Thankfully I have a set of set of valves at my disposal that I stripped out of an N47 years ago. I saved them, because that's what we do. They were sitting on the shelf, and thankfully I've got 24 valves from which to pull the best 12. So exhausts are done and (barring surprises) I think the intakes will be much easier since they are in way better shape.

Haha!! I didn't see stamps on the block for that, but I did see a stamp in the head "F". Here, you can see it to the left of the plug I put in up by the thermostat housing. I'm trying and trying to convince myself that it does not mean "Front":

Wish I were there!!

Wow. Interesting story. Looking forward to more telling pics once you get your hands on the car. That's right in Chuck's back yard!! @cbuczesk

Sorry for not being clear... All of the cylinder are punched with their respective numbers. I didn't take pics of all of them, but here's #4: My issue about "what's the point" is... What possible reason would there be for punching the chambers like that? What's the value add? It's not like they can possibly move around! I can understand it on things like the cam towers where it's possible to get them into the wrong positions, but the cylinders themselves aren't going anywhere!!! Even if you're trying to do something like get the same valves back to where they came from* or something, you don't need numbers. Just look at the head and hope you can count to six? * Side-note BTW - Based on the non-matching wear patterns on my valves and the seats from whence they came, I don't think he did. I believe I've spent the last couple thousand miles re-wearing valves to the wrong cylinders. Working on some of that is the next project on the agenda.

So while I'm logged in and asking stupid questions... Anyone understand the point of doing this? Here's number three:

LOL. No, they're not all out. I haven't done anything with them yet. They're all still in there. So, basically the answer seems to be... "No, there is no logical reason for the lengths of those studs." and the follow-up info of " However... Mess with them only if I'm willing to accept the possible consequences." Roger that. I guess I'll try gently to pull one and see what happens. If it comes out easy, maybe I'll try two. And so on. If the first one seems like it doesn't want to come out, I'll just cut down the extra longs with a hacksaw and call it a day. Yes, they are all-thread, and cut to custom length by hand. I don't think it was part of a kit. And no, they didn't really cause any functional problem. Other than having to screw the nuts on forever, they worked OK. In fact, the only location that was a problem was the front exhaust nut from cylinder #5. Because of the way the header turns forward so close to the head, getting a wrench on that one was a PITA. Haven't figured out what to do about that one yet, but I need to come up with something better than the way it was done before. Anyway... Small problems compared to the big picture.

I got nothing technical to add to this thread. My only question is does it really belong in the "club website" sub-forum? @Mike

So here's another question... My PO used stainless studs for the exhaust instead of the original bolts, and some of them are crazy long. And the positions of the long ones seem almost random. Here's a pic I took during the teardown. There's four super long studs... Three of them easy to see in the pic, and a fourth hidden under the thermostat housing: Question is... Is there some logical reason for the length and the positioning? He clearly did it on purpose. Any ideas? I haven't tried to take any of them out (yet). I'm kinda torn between leaving just sleeping dogs lie and poking them. Based on what I've found elsewhere, I'm a little worried that something might be stripped out of the head or (literally) holding on by a thread.

Thanks again guys. So here's that plug where my PO drilled through into the water jacket. Cut off and now flush: I'll drill and tap for the valve cover bolt later. Now that I've got good metal to work with, that shouldn't be difficult.

That's good enough for me. If you've seen tape like this on other heads, I'm going to assume it's factory and just let the plugs be as they are. Thanks for the data point.