Captain Obvious

SMOKING GUN!!! So I was messing with trying to align the cam towers by loosening them a little bit and trying to get the cam to spin smooth, but #3 kept giving me trouble. Just didn't feel right. So I decided to pull it off completely and see what I could see. And....... Here's what my Previous Owner put in there on one side to "align" the tower to the head: And it gets worse... Notice that since that threaded "thing" is so crappy, it caused the other side alignment ring to be so far off that he had to use the cam tower bolts to jack the tower down (because it was out of alignment). it caught the alignment ring on the other side and pinched it in the gap and smashed it. Here's what used to be the precision alignment ring: The ring got smashed and actually extruded a tongue of material out into the seam between the tower and the head. Pulling that damaged ring out, you can see the dent it left in the aluminum head: At first, I thought that threaded thing was a Helicoil or something, but it was just a short stub of bolt that he drilled out. I guess he lost or mangled the original alignment ring and made that instead. Here's the two pieces that were "aligning" my #3 tower: Previous Owner strikes again!!! It's beyond me how you can't tell that something doesn't feel right as you need a wrench to crank that tower down into place and crushing that alignment ring in the process. I know the hobby is filled with people of varying skill levels, but this surprises even me.

Head is off, and by some incredible stroke of luck.... No contact between pistons and valves!! So I don't know if the engine isn't interference (with the dished pistons), or if I just got lucky and the rear half of the camshaft just happened to stop in a position where none of the valves were open enough to cause a problem, but whatever the reason, I'm thankful for small victories. Here's a pic of the valves from one of the rear cylinders. They all look like this. No clean spots and no hint of collision: My beautiful camshaft. The rear portion spun really easily in the two rear journals. I just slipped it out the rear of the head: The front portion of the camshaft spins relatively easily, but not as easy as the rear half. There is also one part of the front half rotation where it gets a little tighter. Not so tight that I can't turn it by hand, but to my calibrated hands, it's a little tighter in one spot then the rest. I wouldn't be surprised if there's some sort of alignment issue with the cam journals that was stressing the shaft for the past five years. Here's the break area. I don't have any of the typical beach marks of a gradual failure. It looks like it was a one time catastrophic snap: I took the front half out to get a better pic. Here's another close-up: Next chance I get, I'm going to put the front portion of the cam back in and see if I can loosen up the front towers and get them aligned better. I suspect that if I loosen them up and tighten them down again evenly I might be able to get rid of the rotational tight spot. Just to see if I can.

What he said! So how's it running? Cold, hot? Everything stable?

Thanks for the compassion. The general consensus is that the design IS an interference engine. So if that's true, depending on where the cam stopped, there may be some significant carnage. I should know for sure very soon. I don't have a borescope, but I did pull the plugs and have a peek in the holes. I see some stuff in there that doesn't look right. Can't tell if it's evidence of a collision or what, but something in there is weird.

Update on my dead engine project... I made a rocker removal tool. After multiple failures and spending waaaaaay too much time on it, I finally hit on a geometry that worked: I took the rockers out so I could turn the cam without having to worry about valve positions, etc. I put the engine on #1 TDC before taking stuff apart so I knew where everything was. Way easier to spin the engine over with the plugs out and all the rockers removed. Then I made a cam chain wedge tool. My tool is about an inch longer than average because that's just how I roll. I wanted to get the tool down as deep as possible to assure it was holding the tensioner shoe back. I also came up with a (yet to be fully tested and therefore potentially stupid) removal plan. That's the screw on the front and the metal removal handle: Since the tool is longer than most, I had to remove the cam gear bolt to get the tool into place. Being careful not to knock the gear off the end of the cam (not really a difficult task), I took out the bolt, slipped the tool into place, and then put the bolt back in until I was sure the tool was fully seated in place and holding the chain: Here's some pics of that whole process Bolt out just long enough to get the tool to clear the bolt head: Then get the bolt back in place for now: And here's the tool fully installed wedged into place: And here's how the removal tool is supposed to work: Hook the screw head with the hole in the metal handle: And pull the wedge back out: Worked in test. We'll find out later if it works as well in real practice.

I gotta believe there are a lot of people doing this, aren't there? I'm not going to be cheaper than them. You think I would do it better?

Bug away. I'm about 20 miles out of the city, but I can be coerced to drive in if I've got a good reason.

Wow. You guys are great!!

Haha!! You guys are awesome!! Once I get my hands on some ill tempered sea bass, I'll be set!

Hahaha!!!!! It's true!!

Welcome aboard neighbor!! Might be something in this thread that could help maybe? https://www.classiczcars.com/forums/topic/61482-240z-gets-jiggy/#comments

LOL! I have a lathe and I'm not afraid to use it!

Just for proof of concept, before I cut the second perch off, I tested the first one. Used a rubber mallet to tap the now liberated loose perch back onto the strut tube and position it a little lower than it was originally: And here's a shot showing the relative heights of the perches. You can tell by the position of the tab welded onto the tubes that the perch on the left is lower by about an inch. The idea would be to re-weld the perch back into this new lower position on another set of complete strut tubes. :

The process went like this. Chucked them up in the lathe and cut off the remaining lower portion of the original tube: Then once that was out of the way, I went in with a boring tool and opened up the inside diameter: Bore out the ID a little at a time just until the original tube has been cut out of the perch ring. Once that happens, the perch can be pulled off:

You know the radiator is at the other end of the car, right?

LOL. My story didn't quite play out as described by Blue, but there has been non-ideal events occurring all over the place that have pushed the priority of this project back a little. So the short answer to your question is... No, nothing that you haven't already seen. Here's where the project stands. I got the strut tubes from you (I thank you again immensely): I chucked them up in the lathe one at a time and cut the spring perches off the tubes: Here's what they looked like before and after they met Mr. Lathe: And here's both of them done: And that's where the project stalled. They've been helping hold down my workbench since this point.

Wow. You guys have been on a roll in my absence. Glad to provide you with so much amusement at my expense! I would usually deflect stuff like this with "Yeah, whatever. My car runs great", but that's not currently the case. So go ahead... Poke your fun. I'll get even someday!

Ouch. That's not cool, man. (See what I did there?)

Man... It's still too early to admit that. Must have really been eatin' at you. Glad it's running!! We'll never speak of this again.

I'm no timing expert, but I don't think there's really any way to really "compensate" with any static source for not having vacuum advance on the distributor. You could maybe squeak your 10 degree base static timing up a degree or two, but there's just no true "substitute" for the vacuum advance at light cruise.

Happy Canada Day to you all!!!

Well therrrrre's your problem.

Glad it's running!! Woot!! When (if?) you reach the point when you can talk about it, we're all ears.

in 73, I'm not sure if that heat wrap came from the factory or was added by dealers as part of a TSB. If you look at the pics in the FSM's, the heat wrap does not appear in the 73 manual, but it is shown in the pics for 74. @Zup might have some insights. I think he and that wrap stuff have a long and troubled relationship.

Fuel pressure sounds fine. Don't worry about the test #3 - 3 cold start system circuit when it showed voltage immediately. All that means is that your cold start injector never fired. Either your thermotime switch is burned open, or it was just too warm to close, but in any event, that's not what's causing your problem. I've been running with no cold start injector for years now, and it takes a little longer to start, but it still starts. And I will double check my notes, but I don't think your AFM test #1-3b is a problem either. Can we go back to basics.... Are you 1000% sure you have the firing order correct? Are you 1000% sure you have the ignition timing correct? Are you 1000% sure you are getting good spark on more than just one plug?