Zed Head

I'm sure that Zs-ondabrain can explain in depth, but, as I understand the charging system, the L wire does what the "cut-in" speed is doing. I believe that it magnetizes the windings right away so that the alternator can start generating current immediately. The L wire runs through the red charging light (Lamp) on your volt or ammeter. If the red light comes on when you turn the key on, and the other end of the wire is connected to the L terminal, then the windings are getting powered as they should. It goes off when the current starts flowing. Does your red charging light work as it should. Lighted when the key is On, off when the engine starts? I could be iffy on the details, but I'm sure that the red charging light is an integral part of the system and needs to be functional and wired correctly for the system to work as designed.

Actually, you missed my point (no pun intended). I do stand corrected though that the L20B came in carbed form in 1978 in the US. It has been a good discussion. Overall, I learned something and if I ever a get a carbed Datsun I will be ahead.

This has turned in to an interesting technical discussion (aside from all of the extra stuff). Here is a paragraph from the 1972 FSM, in the Emissions section (page EC-13), but it seems to be a general statement that the coolant lines are there for consistency in fuel supply, by keeping the gasoline at a constant temperature through heating of the carburetors. I could not find a comparable page in the 1973 FSM. Draw your own conclusions.

Your page is for a 1978 EFI engine. The discussion is about coolant lines on a 1973 carburated engine. Replay point...

I came across an interesting discussion on this topic over on Hybridz a while ago (link below). Apparently the keyway is mainly for initial indexing, not holding the damper/pulley from rotating out of sync with the crank. The force locking the damper/pulley to the crank comes from the compressive force of the bolt on the crank end. So minor damage to the keyway should not necessitate crank replacement or even repair, if you can live with the knowledge that slot is not straight anymore. Not perfect but might save you some time and money. It's worth a read. Post #21 summarizes pretty well. http://forums.hybridz.org/index.php?/topic/91212-cracked-crank-pulley-worn-woodruff-keys-crank/page__st__20__p__872134__hl__crank%20keyway__fromsearch__1entry872134

I hope you're not looking at the volt meter in the dash. Mine was off by several volts, as I've heard many are. You should measure voltage at the battery with the engine at about 2500 rpm according to the FSM. The FSM for 1976 says 14.3 - 15.3 volts at 68 degrees F. It also recommends measuring amps but the procedure is a little more involved. You still haven't really stated the problem. Does the battery go dead or does it just not charge? Could be different causes...

So the problem is that the battery does not charge correctly? The old-style mechanical regulators are adjustable. Have you measured the voltage at the terminals with the engine at ~1500 - 2000 rpm, to see what the regulator is doing? Need more numbers to make better guesses...

Maybe the can of Seafoam was rattling when you revved the motor. I have actually spent a few moments in the past wondering what "that noise" was from the rear end of the car then realized it was the old beat up speakers behind the seats sliding back and forth...

Click through the choices in the link. You will get to a page that shows a positive and a negative option for the style and size chosen. I second (third, fourth?) the thanks for putting this out there. Much better than what is typically found in the auto parts store.

Never mind. Not a good discussion starter...

Didn't mean to stir things up with my KISS comment. The last S can be inflammatory and that was unintended. So Rocket88, you have options. Since you mentioned that the coolant was flowing along the head/block interface, you should make sure that you look closely at the thermostat housing. It might be starting there, flowing down to the interface, and just showing up between plugs 1 and 2. It's difficult to see up under there, a mirror might help. There are several sensors in the housing that could leak plus the housing gasket itself. Have fun.

Agreeing with the man from OZ... The original post described a very small problem. A "bit of a coolant leak." It goes away completely when the motor warms up. No mention of overheating, oil burning, etc. The post even says "no white smoke" so there is some awareness of the various bad head gasket issues. Just taking off the head can cost extra money and time, for gaskets, broken bolts/studs, possibly failing to secure the timing chain, etc. I would apply the KISS principle here.

You could try some of that "magic" leak stopping powder, like Bar's or other. I had a small external leak from the back of my engine and one bottle of Bar's stopped it.

You are probably supplying another ground path to the battery, through the brace to the mounting points, then on to the negative terminal of the battery. You might have a weak ground wire connection or corroded connection points. I think that the sparks imply that there is some resistance in your current ground path, from the engine to the battery. The main ground for the engine on my car is from the negative terminal of the battery through the heavy gauge wire to a transmission mounting bolt. It would be worth checking yours to make sure it is low resistance.

jacobmccabe92 might have some used... http://www.classiczcars.com/forums/showthread.php?p=327794#post327794

I have a 76 and a 78 parts car and they both have that ugly-looking thing. Zs apparently came from the factory like that, not sure what year it started. It's in the Rear Axle and Suspension section of the FSM, called a "damper plate". It must be designed to damp either vibrations or clunks, I would guess. By the way grantf, I went to see what year car you had and your About Me says that you don't even have a car yet.

My car ran about medium-rare over the winter but since spring is here has been running medium. Coming up the Highway 26 hill the other day I let it rev in 3rd gear just to listen and see how things sounded. It started getting pretty close to done though show I shifted up before I really cooked it. :laugh:

You might think twice about the universals. I replaced all of my half-shaft u-joints because one was bad, thinking that newer is better, but found that the old ones that were still good, were tighter than the brand new ones. I ended up putting two old half-shafts with original u-joints back in. If the u-joint is not loose or dry, it's probably worth leaving alone. You can regrease them by reinserting a Zerk fitting, if they are capped. To add to GreenZZZ's comment - I couldn't tell that my diff mount was bad until I got the cross member unbolted and pried on it. Then it was obvious. With everything bolted together, it's hard to get the leverage, and hard to see what's moving.

My switch was bad when I got my car, a 1976 model, and after reading through the manual and figuring out how it worked I realized that with a bad switch, the car just runs a little dirtier when it's cold. The switch advances timing when cold, I believe, to get it to run cleaner. It's only on the non-CA models. I could be wrong on the reason to advance the timing when cold, but either way, without the switch, the car just has the timing when it's cold that it would have anyway after it warms up. My car runs fine when cold, without the switch working. Once the car warms up, the switch doesn't do anything.

The master cylinder only pushes the pads on to the discs and the shoes on to the drums. It doesn't do any retracting or pulling back, so wouldn't be the cause of your wheels being locked. You should take the front wheel off and see if you can pry the pads and pistons back in to the caliper to get the wheel to turn. You might need new calipers or a rebuild. It sounds like the pistons have rusted/corroded in the bores. Same thing on the back. Take the wheel off and see if you can remove the drum. You will probably have to loosen the adjusting wheel inside, using a screwdriver through the adjustment hole. They tend to be very difficult to remove once they get stuck.

Just to tie this up and for anyone else that wondered, here are a few pictures. The resonator (actually an anti-resonator I believe, by definition?) does neck down a little at the inlet then back out at the outlet so does create a flow restriction. But the interior is pretty smooth. There are some holes in the interior but no "teeth" to create turbulence. For those interested in the esoteric Z stuff... (and of course, the obligatory shoe photo - Asics)

The water temp sensor tells the ECU how long to open the injectors. The colder it is the higher the resistance value. If it goes bad, giving infinite resistance, or you have a broken connection it will tell the ECU that your engine is stone cold and the ECU will continue to pour on the gas. Page EF-23 and EF-32 of the 78 FSM describe the test procedures (sorry, the 77 FSM is too hard to find things in). Measure across Pin 13 to ground. If you get infinite resistance you probably have a bad sensor or a bad connection. Resistance should be about 2.5 k-ohms at 70 F. 76 uses Pin 13 also so it's a good bet that 77 does too. The thermotime switch just cuts powers to the cold start valve if the engine is warm or if it's been cranked over recently, I believe.

Thanks for the insights ZCurves. I will try to avoid the Olds sound, but am not ready for Twice Pipes. Baby steps.

I have a complete original exhaust system from a 1978 Z that I am going to install on my 1976 280Z, non-CA model, to replace the original one, since someone smashed the exhaust pipe up against the differential when lifting, to about half volume. Plus the $30 O'Reilly's Cherry Bomb turbo muffler just doesn't sound right. Could anyone tell me what is inside the small "pre-muffler" up next to the transmission? The little mini-muffler. It looks to me like a place-holder for the California model's catalytic converter. Is it just hollow or does it create a flow restriction? If it's hollow I will just get a new muffler and install it as is, saving on gaskets and effort. If it is a significant flow restriction I will replace it with something else before installing. Thanks for any comments.

I have a flare wrench too but it has not always worked. Looking at those pictures, it may be vise-grip time. Once the points of the nut are rounded the wrenches are less effective. If you take great care in placing the vise-grips, and make sure the jaws still have good serrations, you can break those fittings loose with minimal damage. If you feel the grips slipping at all, stop and reset. And before you start, you should file the twisted off points of the brake fitting nut down flat to give a good gripping surface. The actual twisting of the wrench or vise-grip is 5% of the time involved. Getting the grip set is the other 95%. I have actually filed new serrations on my old vise-grips to get them to do the job. Clean the vise-grip jaws and the nut of any oil, grease or fluid. Any slippage at all is bad. Get everything set, double-check, then apply twisting force. If they are that tight, you may also bust a knuckle when it lets go, so have a band-aid ready. You can get pre-cut lines with the right fittings already flared on at most auto parts stores, for the short hard line. They are inexpensive. I made a bending jig with screws and wood but you can borrow real bending tools from the parts stores. Just take the old piece in to make sure you get the right style and length. If you decide that the hose is coming off no matter what, you could use a torch. Put a torch on the big end, watch out for bubbling brake fluid. Of course, once you bake the rubber hose, there is no going back.