Captain Obvious

Word.

I've only got one of my pistons here (the rest are out at GGRs), but the one I have here was assembled like the one you pictured above. And I'm confident that the one I have here was NOT one of the two bolts that came out during disassembly. (Point is, I have high confidence that the one I have here is the way it came from the factory.) I don't know if my other five pistons are like the one I have here but I'll let you know when I get a chance.

Although, I'm not convinced that "interchanging rod bolts has the same effect as interchanging rods and caps". I think interchanging rods and caps is much more risky than interchanging rod bolts. As a testament to that... You can buy and install a whole new set of rod bolts. In fact, some people even recommend that. Of course, it would be a better idea to keep everything together and in the exact same orientation as it was originally, but I certainly don't think it's as high an impact as mixing up all the caps.

I'm guessing the reason it's important to keep the rod bolts in the original location is that they locate the lower bearing cap against the bottom of the rod. Take a look at the rod bolts... there's a thicker section up by the head. That thicker section is a locating shaft for the caps. Now that you mentioned it, I've got to take care of that too. I dropped two of them and I'm relatively sure I got them back in the original orientation. I know they're on the right rod and the correct side of that rod... Only thing I'm not positive about is the rotational orientation. When mine fell out, I put them back with what looked like (in crappy light) the cleaner side towards the rod, but I need to double check them now. Have you looked at yours to see if you can use the oil staining as a guide?

Good progress. I'm with you... I'd put a little sealant around the oil holes and the water holes. The rest of that gasket's sealing work is oil, but it's not under pressure.

Yup. That's exactly what I meant. So the ITM has the timing marks, and according to Dave, so does the OSK.

As suggested, a hook on a slide hammer tool (or a crude substitute) would probably pop that out. Or just let the machine shop take care of it. It won't add any significant cost. Did you get the front one out? If not, be careful drilling that one too. #1 is close behind that front plug.

If it makes you feel any better, that's not the first time I've heard of that. I haven't done it (yet), but apparently it's easier than expected to do that. I don't think you are the only one.

Cool. Those are available all over the place for cheap. And you said it definitely has the timing gashes on the back of the gear?

Definitely weird. Would be more confident in a repair if we knew definitively knew what really happened. That tight side guide is normally under such low stress. I'm having a hard time understanding how a worn chain could cause that failure. That side should always be tight, regardless if the chain is worn or not. Maybe it's in there slapping around side to side and hit some harmonic. Slapping against that guide and setting up some resonance until it broke the mount. Regardless... Let's not do that again. Ever.

That's a little disconcerting. Now I really wonder what happened there!

He said the bolts were still there and tight. The tensioner snapped right off the bolts.

Thanks for that. There are plenty of ITM kits on the web, but I could never find a pic of the back of the timing gear. The pics were always the front side. So what was the kit number you got? Was it the ITM 053-90400? So far, from pics I've seen... TRW S462 has the marks. Beck Arnley 025-0266 has the marks You say ITM has the marks. Melling does not have the timing marks.

Woof. That's not pretty. Would be really interesting to figure out exactly what happened with that. Did the mounting tabs crack off first and then the guide got pulled into the chain? Or did the guide get snagged by the chain somehow and when it got pulled in, the mounting tabs snapped. Maybe the mounting bolts came loose and it was in there flopping around until it got snagged. And then the snag snapped the tabs. So your tensioner shoe was still in the hole? It didn't pop out, right? And for replacement timing sets, it was probably me that mentioned some of them have the timing gashes on the rear and some of them don't. I was talking about it in Av8ferg's thread here: https://www.classiczcars.com/forums/topic/62852-l28-from-82-zx-teardown/?page=2&tab=comments#comment-584389

So the project seems to be going pretty much according to plan. That's good news! (So far.) Yeah, you might get some coolant spillage down into the sump, but I think if you pull the block drain first (big plug on the left side near the rear of the motor) and let the coolant out there, it'll be minimal. I believe that drain hole in the block is lower than the water pump holes. Certainly less than if you pull the front cover without pulling that drain plug first. And if you do get some coolant in the oil, most of it (being more dense than the oil) should sink to the bottom of the sump and come out with an oil change. And regardless, I would recommend that you change the oil after this process just because it's likely you'll dislodge some junk anyway. And nobody likes dislodged junk.

Roger that. Well good luck with it, whichever path forward you choose, and let me know if there's anything I can do from a distance to help.

Exactly. Small reduction in effort, but every little bit helps, right? Other trouble spots? Getting the BF bolt out of the front pulley will likely require impact gun. You got one of those? I recently pulled the front cover off my F54 block, and it was stuck on there pretty good. I had to really work at it to get it off, and that was with the head already off!! It can only be worse if you have it pinched between the head and the pan. But the bottom line... If both bolts came out of that guide, you're gonna have to pull the front cover. No way you can get to that lower bolt with the cover in place.

Here's another pic so you can see how far the guides go up into the head:

Here's a pic of what you're dealing with:

So you're thinking that the guide bolts came completely out? Both of them, or just the top one? If it's just the top one, you might maybe possibly be able to put that back together from the topside by working down in the hole. If the old bolt fell down into the oil pan, it's unlikely to cause damage down there. It should sink like an anvil, and it's too big to get past the screen on the oil pump pickup. Just don't slip and drop a 10mm socket down there as well. On edit - I'm no engine expert, but my read on that left side guide is that it's there just to keep the chain from slapping around. Under normal circumstances, it doesn't even really contact the chain and doesn't add any tension. If you could get it back into place, it's not critical to get adjusted perfect. However, if the lower bolt came out too, or is loose, you're fubar

Well if you've got that as an option that you've been itching to try out, then go for it! If you decide to look into the one that's on the car, then the procedure you outlined above looks pretty good. Only things I would change/remove are: a) You don't have to pull the water pump off the timing cover. You can leave the pump attached and it will come off with the cover. b) You will have to pull the oil pan bolts around the front of the engine that thread into the bottom of the timing cover.

Wait.... Slow down. Which guide are you talking about? The tight side (left) or the loose side (right)? If it was the tight side that came loose, you probably (maybe?) did not pop your tensioner. Have you got any pics?

The two project motors in the same location! Mine's the one on the left, GGR on the right. We'll make sure we don't get parts mixed up between the two.

I just rebuilt the upper end (just the upper end) of my broken cam motor and I'm getting the same blue smoke on deceleration that you are. My first thought was that some of the valve seals had popped off or weren't seated properly. I did the ol' rope stuffed into the cylinder trick and pulled a couple of the springs back out to have a look and didn't find anything amiss. And since then, I've tried my best to visually verify that the rest of the seals are down where they're supposed to be. With limited success, I've confirmed that all the seals look like they're seated. So, assuming that all the seals ARE seated properly, my second thought goes like this... Before the upper end rebuild, most of my valves were not sealing properly, and I'm theorizing now that I've done the upper end rebuild they are sealing much better. Better valves, higher vacuum, and I'm thinking that maybe I'm pulling more oil up past the rings than I was before. I get a good puff of blue at the bottom after coasting down a big hill. Especially if the RPMs were above the fuel cut-off level. Then once the fuel starts spraying in again, all the oil which had built up in the cylinders (while the cylinders weren't firing at all) is all burned at once. That, or maybe there's something wrong with the sealed power valve seals that I used. There was some discussion, by me, about that possibility in the past. What valve stem seal brand did you use?

For the big casting flash seams on the outside of the head, I just used a carbide bit on a dremel. I didn't take any after shots, but this is what I started with. I buzzed off the worst of it with the dremel and then finished with a hand file: