Zed Head

Odd that the front case has a different tone than the back one. It might have already been opened at least once. Who knows, it might have had a "dirty" rebuild. Check the bearings and synchros they might already be newish. It's pretty easy to split the cases and pull the gear cluster out without special tools.

Here's a popular one. I read about it for use with transmissions. You can disassemble easily if you make a mistake, so I got some. It ends up as a very thick goo after it dries. The solvent, or carrier fluid, smells like ethanol (in the Hylomar Blue). Says fuel resistant. http://hylomar.com/hylomar-product-range/gasket-jointing-compounds/

I've seen marbles used. You could probably use gravel also. Crushed 1/2" minus might be about right. It will pack well in your driveway or sidewalk also, afterward.

Here's another "heat range" definition. The term "heat range" is inherently confusing I think. Not sure why they picked that term. I would have used something like "operating temperature". My first guess. Anyway, NGK gives simple description of "self-cleaning". Why is Denso talking about gas pocket capacity? What the heck does that even mean? The simple answer for Jalex's issue is the last sentence, I think. Of course, then you have to define "ultimately". https://ngksparkplugs.com/en/resources/understanding-spark-plug-heat-range "UNDERSTANDING SPARK PLUG HEAT RANGE One of the most misunderstood aspects of spark plugs is its heat range. It is believed by many that the heat range measures spark temperature or intensity. This is incorrect as the heat range is actually a measurement of the plug’s ability to transfer heat away from the tip of the spark plug. One cannot change the temperature of how hot a fuel burns. A hot spark plug has an insulator design that will be slower to draw heat away from the plug tip (thinner insulator mass), whereas a cold plug has an insulator design that will be faster to draw heat away from the plug tip (thicker insulator mass). For a spark plug to function properly it must have a tip temperature hot enough to invoke self-cleaning, while remaining cool enough to avoid pre-ignition. For most vehicles, the factory recommended heat range is sufficient; however, on some modified or special-use engines, alternative heat ranges may be necessary. Often hotter heat ranges have been used to attempt to correct an underlying fuel or oil consumption problem; this is merely a cover-up fix and the underlying issues will ultimately have to be addressed."

You could plumb one of these up in to the cabin. It's funny, but I had to do a similar starting routine on my EFI engine after I removed the cold start valve. Crank for a couple of seconds, wait for fuel to vaporize around the intake valves., then fire it up. That was only after it had sat for a couple of weeks. https://www.dhgate.com/product/fuel-pump-hand-primer-bulb-all-fuels-length/404919119.html#seo=WAP

Here's something interesting. Somehow, the part number for a spring and a distributor are the same in carpartsmanual. I found a complete distributor $96.80. That's what it says anyway. It's a "from Sept. 71" model. http://www.carpartsmanual.com/datsun/Z-1969-1978/electrical/distributor/240z/for-manual/from-sep-71 https://www.nissanpartsdeal.com/parts/nissan-distributor~22100-n3300.html

Here's an old conversation about springs and stuff. You might find a few interesting points to ponder in it.

He's only going to get about $50-100 from a wrecking yard. The engine trans and diff would probably be worth picking up as a set. It only takes one of them to be good and the buyer is probably paid back. Buy those and let him scrap the rest. Even a set of good injectors, a fuel rail, and an FPR might make it worthwhile. A garage full of spare parts gives comfort. @Terrapin Z is a collector and has been known to travel.

Might be some recommendations in here. Seems like wheel bearing grease would be fine.

How about a bad valve seal? And, the oil rings scrape oil, the compression rings create pressure. You can have a bad oil ring with good compression rings. A possibility. This is an old California Datsun engine, maybe Datsun Parts LLC. Quality was suspected from the start. I'd put that hotter plug in and just drive it.

AV8ferg just went through the same thought process, almost exactly.

Did it run? Is it complete? Carbs, manifolds, etc.? I'd add a few more pictures than just the serial number and head casting. It's neat but if the guy with the car it came from isn't out there, it's really no different than a later E31 headed L24. No offense. There's only one car that will be "numbers matching". 2776 is the number.

If you're trying to save money on your rebuild and you have kept track of which rocker arms match which cam lobes, you might want to just use the cam in the best condition. Also, the 74, and maybe the 77, might be spray bar cams. No internal lubrication holes. So that might be a factor. The specs for all of the cams are similar as you can see in Jeff G's chart. There are no "hot" cams. Here's the P79 data if you want to take some measurements. Just from the picture it doesn't look it's been reground. Don't lose or throw away any of the small parts, like lash pads. They're expensive when you consider that you have to buy 12 each. Getting hard to find sizes also.

Bees against murder hornets. https://www.yahoo.com/huffpost/honey-bees-kill-cook-murder-hornet-113739412.html

The question of the definition of "friction modified" has come up before. The label doesn't say "modifier" it says modified. So, not the same as friction modifier for a clutch type limited slip differential, which is modifying the slippage between clutch discs, not synchro rings. Besides that "modified" just means different. It doesn't really say which way or how the modification is happening. But, besides all that, and what "friction modified" actually means it just boils down to the fact that people have tried it and compared it to the "normal" transmission oils and it works a lot better in removing the poor synchro perfromance. Redline MT90, Synchromesh, and Synchromesh Friction-modified all work very well. Also, Swepco 201 blended with ATF works very well also. Better than Valvoline 80W-90 manual transmission fluid. I don't think that anyone really knows exactly why one works better than another. It's magic.

Are you looking at the AC chapter? The hoses actually have small labels taped to them with letters that show where they go.

Found a video if you decide to dig in to them. This guy posted here for a while but now has his own web page. Some pretty good stuff on it. http://woodworkerb.com/home/datsun-240z-rebuild/datsun-240z-mechanical-fuel-pump-rebuild/

Found a dyno run with numbers, in the title. Apparently it's the factory system. But he doesn't show the numbers with the FAST system. Don't know why he doesn't put it on the web site page. He has a bunch of videos on his account. https://www.youtube.com/channel/UCAvjCjvssZ_1BcTC1Rdx69A/videos

Here are his youtube videos. They're half off the page on my computer on his web page so I thought I'd link them here to make it easy. It will produce an engine that runs. 8 seconds of engine noise. No dyno sheet. Installing...

There's an old discussion about it on the forum. People wanted to see an engine with the system installed and the engine running, maybe even a driving video. Never heard back. Basically, it looks neat but there's no evidence about how it will actually do with the L6. It might be as bad as the L-Jet system with a big cam. Who knows, no way to be sure. If I was marketing that system I'd install it on an engine with a big cam to show what it can do, and make a video to prove it. Found it -

EuroDat explained it in the post below. There's a spring inside the 280Z style slave cylinder that takes up all of the play at the clutch fork. It can't apply much force, it's a small spring, but it is there and it does work. If I was checking that theory out I'd crawl or reach under the car with the engine running and move the fork away from the pressure plate by hand. You can reach it from the engine bay also. You might have to have someone sit in the car to listen since the noise is amplified in the cabin. Here's the FSM drawing. I put a red dot under one of the spring coils.

I think that this was a good idea, below, and it's telling about the valve quality. Maybe you can find an old Nikki pump. Pretty common to have to fix new aftermarket parts.

Does the filter run dry while the engine is running?

oops

You can't make this stuff up, it's real. Live and Let Die. It's not even the McCartney version.