Zed Head

There's a conversation going on about modifying old Z cars. Made me think of this Gas Monkey Garage car that got hacked up, probably because the show is running out of ideas (Tequila and a hamburger anyone?). Sorry, there's an ad to suffer through first - Take a collectible classic and cut it up so bad that it can never be restored. Also just saw an article about putting batteries in old cars. They'll probably do that next. zzzzzzzzzzzzzzzzzzzzzzt. http://www.bbc.com/autos/story/20150521-vintage-gas-guzzlers-ripe-for-a-battery-powered-reboot

Have you measured anything? Fuel pressure, timing, engine temperature (there's a gauge in the dash, with numbers), resistance values at the ECU? The bogging out could be a clogged fuel system, maybe in the fuel tank. Leaving a pressure gauge hooked up until the problem happens is the best way to see that. When you say "shut off while driving" do you mean at idle, while going 50 mph, while accelerating, dies then restarts, loses power like it's about to die, makes dying noises? See the problem? Those are all "shut off" but there are different possible reasons for each one. If it happens while driving it could be the ignition module. I've solved a lot of problems just by trying to figure out how to tell someone else what the problem is. You need to do more work on the description. "Die", "shut off", and "bog" are not enough. Sorry, that's just the way it is. All we have out here are the words you write and the pictures. You've only posted three numbers, one was the year of car, and the other two were RPM. Did the car sit for a long time before you got it (how long) or was someone driving it?

You're way ahead of many in that your car runs. And that it used to run well before you "cleaned up" the intake manifold. But you'll need to get in to the fine details to get it back to where it was before. Even that little vacuum port will change the air-fuel ratio a small amount. Add up several like that and it's a big effect. Good luck.

EFI just requires more accuracy and precision than this. Seriously. "Random" and "need for air" just won't get it done, you have to get numbers. It seems difficult but once you make some progress you'll see the value. The EFI system just can't be beat on like old carb systems can. Here's a case study on how to go from bad to good - http://www.classiczcars.com/topic/51367-project-boondoggle-or-so-i-went-and-bought-a-z/ http://www.classiczcars.com/topic/51531-sanity-check-on-280z-fi-tests/

Nice. Even when the things that should work, do work, it's still a surprise. Those are low numbers. Consider the coolant circuit potentiometer tweak for adding a little bit of fuel, if it's lean. Many of us use it,

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.