Zed Head

If you tighten the spring the fuel/air ratio gets leaner. Loosen and it gets richer. Adjusting the AFM away from the factory setting should never be necessary on a stock engine. Stock cam, head, intake system, etc. If you can tell where the old marks are you should put it back to that spot. The cover over the EGR port could be a problem if it leaks. It's also possible that your EGR passage is corroded inside and leaking. You should be able to see ii it is by looking under the cover you've applied. Both of those will make things lean if you've also removed the EGR exhaust tube. If the exhaust tube is still connected it won't be leaner but it will be weaker. Can't tell from your picture also, if you blocked the CSV hole well or not. Vacuum leaks can add up. And when describing the problem, you should tell whether the engine is hot, cold or warm. There is a temperature actuated switch that can affect timing, which will affect the way the engine runs.

Good eye. I looked closer and there's a huge leak in the boot between the AFM and the TB. Massive quantity of unmetered air. I'm going to guess that "tightening" means adjusting the AFM cog for more fuel. Probably didn't mark the starting point either. More tears...

Nice work!. In your picture it looks like 3 and 18 are open, and 2 and 18 are closed, which is correct for idle. But you can see how it works, with the common center pin moving closer to 3 as the throttle opens, if I'm looking at it right. You should be able to see it touch, and maybe even a tiny spark if you open the throttle with the key on. But it looks like you should have some rotation possible before 3 and 18 contact. You might check the connection itself for dirt and grime or a short. It does look futzed with. The two screws are different and one has been abused. I would go ahead and loosen those two screws and adjust it until you get the right numbers, if you can. That's an important circuit and could explain your problem.

This level of detail will not work with the EFI system. What does it mean? What was tightened? You have a long frustrating path ahead.

Are you asking for the part number for a 1979 280ZX ignition relay? Or help with the no-crank problem? You didn't mention finding the short that caused the fusible link to smoke, or if the 30 amp fuse blew when you tried to start it again.

I'll add to what I mentioned before. Connect a long hose to the outlet (inlet to the pump) fitting. Long so that you can keep one end above the level of the fuel so it won't leak out. Blow air in to the hose while watching the suspect spot. If there's a hole there you should see small bubbles as soon as air pressure pushes the fuel level below the spot. Moderate the pressure to avoid emptying the tube and blowing bubbles at the hard line inlet on the bottom of the tank. Best method would probably be like the cartoon guy in the Service Manuals.

I overlooked that 30,000 connection. 130,000 maybe? So the rings should be well-seated by now. Hopefully not worn out. Sounds like the head wasn't even rebuilt. Lapping used valves, no mention of valve seat replacement. Not sure what that means. The good news is that these engines last many, many miles. Many more than the typical US domestic Chevy, Ford or Mopar engine. Basically, it sounds like you have a used engine that has head the head gasket replaced and the intake runners ported. Still not sure what you could do to feel more confident besides running it. I've run engines in my garage, on the floor. Actually just one engine. A running engine in the living room - that video might go viral.

Brand new parts don't seal like used. Rings have to seat. The valve lash will affect spinning engine pressure numbers because it controls when the valves seal the chamber, but leak-down is a static operation. So valve lash shouldn't have an effect on leak-down results. But leak-down results will be suspect because the rings haven't worn-in. Not sure you'll be able to verify good parts and assembly by testing. How unknown is it? You knew " The head was apparently rebuilt, onto a block with about 30,000 miles." There must be a little bit more. Even if you took the head off, you'd only be able to check valve seats, and cylinder wall finish. Might as well install, break it in and hope. Aside from a complete tear-down with measurements, doesn't seem like there's much else you can do.

Did you get more stopping power or easier stopping power? If you can lock up the tires you have maximum stopping power. A bigger booster will also give easier stopping power. There are reasons to go for rear discs over drum but sometimes they aren't clearly defined.

How fast is "by hand"? Wrench on the crankshaft bolt or two hands on the pulley? I like the smell of gear oil.

It's usually the hard lines that need replacing. They work-harden when compressed and don't take the proper set on later re-assemblies. They can even crack. The seat in the valve just needs to be smooth and gouge-free. You could probably get straight lines at the local parts store and bend them to fit.

You could probably "fully line" yours and solve your problem. Coat the hole closed. And, thinking, on a 240Z, which may not have intricate baffles inside, maybe you could just punch a hole in the tank and run a new tube. I've seen people put supply lines through the drain plug also. Just saying, a decent speed shop might fix your problem and give you a better tank for less money. First - confirm problem. If you can get the scope close maybe you could blow air through the fuel hose and look for bubbles.

People cut open tanks to install baffles and internal pumps. Pretty sure it's doable, not uncommon.

Ozdat says the N47 chamber is 44.6 cc. Is the Blue N47 head milled?

If you have a shop vac you can rig up a hose to get in to the crevices. I would just worry about dropping a chunk of sludge where it could do some harm, trying to spoon it out. It's not going anywhere otherwise, unless you plan to hit some bumps at high speed. My old engine had worn valve seals that leaked oil in to the intake runners. If you're looking for work, new seals might clean up emissions a bit. I still passed though with my old seals.

How bent is the bent one and how straight is the straight one? Just curious. I have an N42 head with a.007" upward bow in the middle. It actually worked fine on the engine, but leaked coolant from the rear passenger corner. The Modify book describes how to bend a bent head back to straight. Also says that up to .015" bend can just be milled, both sides, without straightening.

Did you use an adapter with your pressure gauge? They add a lot of volume and will lower the numbers quite a bit. Better to take the numbers on a warm engine also. Plus, if the oil is gas-thinned from running rich you'll get a poor seal. Cylinder pressure tests are mainly good for comparing quality between cylinders. You're looking for consistency. The 30 psi bump with added oil and the sludge do suggest high miles and wear though. But you'll probably be able to get it to run well and pass emissions, it might just burn some oil and smoke a little bit. The valve adjustment might have a significant effect, since it's possible it hasn't been done while all of that sludge was building up.

Many would say the Haynes manual is not worth having. With the year-specific factory manual available, the generality of the Haynes manual will cause it to gather dust. 1970 - 1978 covers carbs to EFI, and narrow bumper to wide. Can't fit all of that in to one book without cutting corners.

Weren't you just looking for the aluminum? The head. One free bent head with a cam, and one $150 straight head with no cam. = one $150 straight head with a cam. There's a 1982 Maxima in the Vancouver, WA Pick n Pull right now. If you know someone out here.

Look at the T plug in the back. It will probably have an S and L molded in to the case. That would be an internally regulated alternator, probably 60 amp. Or look for a P terminal. The ZX alternators had a P, I think that means internal also. Externals have F's and N's, instead of S's and L's. I think the T plug's in a different spot also maybe. Compare RockAuto pictures, 1972 versus 1981 for example.

My brain's not working at 100% right now but it seems to be on the wrong side of the block, and the thermostat housing looks weird and the timing tab doesn't look right. What's going on with that engine? If it bolts on, and has an S and an L, and the pulley will turn it, it will work. Gotta be numbers on there somewhere.

The Nissan 70 amp alt. is NLA from Nissan and the parts rebuilders just make everything 60 amps. So there is no 70 amp available. You can change the pulley, and shave the case, and rewire a 90 amp 90's year Maxima alternator and it will bolt in to the brackets. It takes some effort but it works. Or you can go with one of the super-duper alternators here: http://www.datsunstore.com/advanced_search_result.php?keywords=alternator&osCsid=856ee9bb129c2155c9dd2874e96c12c6&x=0&y=0 By upgrade you probably mean getting rid of the external regulator. The last link is a "one-wire" setup. The Maxima alt. will require some modifications at the old plug.

There's a lot of either outright wrongness or confusion in that ad. 425 HP (500 minus the nitrous) from 11 lbs of boost on what looks like a fairly stock L28 turbo engine. $70,000 spent on what looks like a fairly stock 240Z with a paint job and not much engine work. Not seeing the value. Says L24 in the description, L28 in the text. Wrong VIN. Says AC, but later says it's just an AC compressor hanging off the engine. "Track ready" implies that it won't pass emissions in CA. But, at least, the emergency brake works. With perfect idle and no overheating issues. Notice the last part says "we". Looks like a dealer picked up a car for cheap and is selling for all they can milk out of it. I'll bet the seller is not the builder.

That's a good method. One of those wires is on the pressure differential switch just below the master cylinder. Could be the brake warning lamp check relay that site mentioned (indirectly) also.

Except the light. Your mechanic should have checked that also. It's part of the system.