Nex

Alright, we made a bit more progress on this. Cranking with the valve cover off got us no oil out of the cam, and we pulled the cam pulley bolt, and found next to no oil inside. Then we pulled the oil filter, and cranked it, and didn't get any oil there either. I suspect that we tilted the engine too much after installing the oil pump, and we managed to dump the oil we used to prime the pump out. So we pulled off the oil pump, re-primed it, and then we got a good amount of oil from the oil filter while cranking, but still no oil from the cam (after reinstalling the filter.) We replaced the valve cover and fired it up again, and by removing the oil filler cap, could see that some oil was coming from the visible cam lobes, in droplet form, without enough force to actually come out of the filler hole. I don't really know what to expect, but I feel like that wasn't the proper amount of oil flow. We let it warm up for a bit (still some white smoke from the valve cover vent,) and pulled the valve cover again, and things looked better than they had the first time - the lobes that were dry and burned were at least a bit lubricated, and the dark / burned color had lessened significantly. I decided to go ahead with the hot lash adjustment, and discovered that a few things probably went wrong during my initial adjustment (The rocker springs were moving things around a bit, and I didn't press the rockers to the lash pads / valve stems, so who knows what I was adjusting,) because some rockers were quite a ways out of tolerance. I didn't measure just how far, but I think I'm lucky that I didn't lose a lash pad. The worse-adjusted rocker happened to be one of the previously over-heated lobes. Question: Could significantly out of whack lash settings have been the difference between the burned lobes and the others? Next steps are probably to drop the oil pan and see if we managed to clog the pickup strainer, then replace the oil pump.

Since you've got to remove the timing chain, this level of tear down doesn't seem like much fun at all to do in the car. You'll have to remove the radiator, and probably some bits of the front of the car, depending on what you've got up there. And then there's the crank pulley... I think if we find any oil supply issues to the cam, we're going to pull it and the cam towers (already did that once to add spacers, won't be a problem) and see what we can see.

Yeah, the oil filter is new as well. Did your metal debris get into your oil pump / did you still have oil pressure? We sort of neglected to do much to the oil pump during the rebuild, because it rather stuck together, and we eventually gave up getting it apart when the trusty rubber mallet got us nowhere. Plus we had good oil pressure before the rebuild, so we just sort of hoped that it was alright. There is (unfortunately) a decent chance that we put everything back together with some sort of debris in an oil passage, and it's now lodged somewhere important... Oh well, we'll see if we're getting oil, then move on from there. And yes, I'd already realized that there should be no spark. Just our luck that'd be the first time it decides to fire up on the first try, and the oil would be flowing just fine...

Wow, I didn't notice that, definitely not intentional. I doubt that it'd do much to the neighboring lobes, but it's probably bent a bit out of shape... I'll have to make a note to check all of them. I'll try cranking it with the cover off when I get a chance to work on it, this weekend most likely.

Yeah, all of the other lobes are well-lubed, and I applied generous amounts of moly grease before firing it up. I don't particularly like the idea of cranking it with the cover off, but that might be what we need to do to eliminate some possibilities...

After months of generally learning things the hard way, and making very slow progress, we've finally got the engine back in our Z, and gotten it started. After ~30 minutes of idling the initial smoke (header paint) had subsided, and left us with just a bit of oil smoke drifting from the valve cover vent, which isn't currently attached to anything. After we let it run, we pulled off the valve cover to do a hot lash adjustment, and saw this: My camera skills are lacking, but those two lobes, #4 Intake and #5 Exhaust, look different from the others - quite a lot darker and drier. I should probably mention that we had the cam reground by Delta, and are using OEM rockers resurfaced by same. When we first got the head apart, the lobes, rockers, head, and cam towers in that area all looked over-heated to some degree, and those two lobes looked the worst. We figured that this was due to the rogue spark plug tip conveniently left to rattle around in cylinder #4 by the previous owner. In any case, after this first 30 minute run, all of the lobes, save the two in the center of the attached picture, looked more or less freshly-machined, with the occasional bit of wear just starting to form, but also uniformly and completely coated in oil (Valvoline VR1,) while the two questionable lobes were dark around the entire surface, and completely dry where they contacted the rocker. When I pulled the valve cover off, there were a few wisps of oil smoke still drifting off them, leading me to believe that they were the source of the smoke observed while running. I've got two theories as to what the problem is, both of which I'd rather not have to deal with. A) These two lobes over heated before the rebuild, enough to damage the heat treating. That could cause increased friction with the rocker, heat things up, and boil off the oil. There are a couple clogs in the oil passage within the cam, reducing or stopping oil supply to those two lobes. I fished around inside the oil ports in the cam with a length of wire, and couldn't decide whether anything was blocked or not. The wire came out with a bit of black gunk on it, which didn't seem to have any smell. We do, by the way, have a decent oil pressure, though the gauge leaves something to be desired in the precision department - I'd guess it was indicating around 60psi. Hopefully someone out there with a bit more experience can tell that I don't actually need a new cam shaft.

Thanks for the quick reply! I'm pretty sure about the shim measurement, but I can't repeat it, since I promptly dropped and destroyed my 1" micrometer after my first measurement. The previous rebuild doesn't seem to have been done with any particular care, so these shims may just have been 'close enough.' And yeah, I know there is more to the mod than the shave, going with the cam tower spacers and N47 valves.

I'm currently working on rebuilding my p79 head, which has damage to multiple quench pads, thanks to some foreign objects in the cylinders. My original plan was to do the 0.080" shave, but as I've dismantled the head I've become more and more worried that the previous owner may already have shaved it some. So now I've got to figure out A) has the head been shaved, and if so, how much. My big hint that it's been shaved are cam tower shims, which I haven't seen in pictures of stock heads. They measure 0.0172" thick, which doesn't seem to line up with any that I've seen for sale, or any standard sheet metal thickness (in between 26 and 27 gauge.) The bottom surface of the head has clear machining grooves in it, but I haven't seen an unmodified head to know if they're original or not. Other than some marks transfered from the head gasket, the bottom of the head is totally blank - there are markings stamped into the top end of the block, so maybe heads came with markings too? If so, that'd confirm that it has been shaved, at least some. Does anyone have a disassembled p79 head available to measure so I have something to compare to? Mine is 4.229" from head gasket surface to the valve cover gasket surface. If anyone has better ideas on how to determine the amount that I need to shave in order to get a total of 0.080" shaved over all, I'd be glad to hear it. Thanks, Nex.