Zed Head

Do you have the Bosch part number? I have a set on my car, from a wrecking yard car, and they work very well. I've never actually seen a cross-reference of numbers for Bosch to Nissan though.

What color are your injectors and what are the numbers on the side (tiny numbers on the plastic)? The assumption has been that you're working with stock parts, but since you've found that your AFM was leaned out, maybe someone has misguidedly installed turbo injectors for "turbo" performance and leaned out the AFM to try to make them work. Just a guess, but worth confirming that you have the right ones. The stock Nisaan injectors for the 280Zs and ZXs were either tan or green. Turbo injectors are a purplish brown color. There are other injectors that have the same form also, like Bosch injectors.

It's a stock part. There are drawings in the FSM, AC section, of where it mounts. The threaded holes will still be there. You 'll need one of them at least if you want your heater controls to work. That might include the vent, depending on year of car. All they need is a vacuum source and the correct wire hooked up, easy.

I would try driving it (start it in first gear) and getting on and off the throttle, with the clutch pedal down, to shock the clutch free. Same effect, just tapping it free instead of pounding it with a huge sledge. I assume that you've confirmed that the slave cylinder actually moves the fork when the clutch pedal is pressed. New parts have been known to be bad.

Saw your post about your collector pipe on another forum and though for sure that someone would respond that it was not stock. I have three 280Z collector pipes and they all look like the attached picture. I have a portion of a ZX pipe also and it looks similar.

Might be a magnet valve. If so, you have disabled the heater and AC controls. What's the other side look like?

Have you done the testing of the AFM described in the FSM? At least the resistance measurements? You can do those without removing the cover. You might be about to waste a lot of money. When the AFMs fail, the signs are usually poor, "stuttery", jerky acceleration with popping back through the intake manifold. Running rich is not a typical failure mode. I looked back through your thread and it doesn't indicate AFM problems. Replacing the AFM is not a cure-all, even though it seems like a magic piece of technology. If the cover is chipped you might as well pry it off. There really is nothing holding it on but the silicone, not even a clip or two. It would probably fall off without the adhesive.

Just replaced my brake pads with some Beck Arnley 089-0020 pads, from Rock Auto, and after a few hundred miles I noticed some noise. It sounded a lot like a wheel bearing going bad, but other times it sounded like something small caught between the disc and pad, like a piece of gravel. Sometimes there was no noise at all. But it wasn't consistent enough to decide which source was most likely, so I took the pads back out to look, before changing bearings that had seemed fine before. What I found was that the paint, a thick coating, on the sides of the pads had debonded from the pad material and was sticking up like a reed, rubbing on the disc. Apparently, if the orientation and/or position was right it would make noise without the brakes being applied. With the pads off I stuck a razor blade between the paint and pad material and peeled/chipped off all of the excess paint from the sides of the pad material. Reinstalled and the noise was gone, I've put enough miles on to be sure it's for good. Just posting for future reference in case anyone has the same issue. I might guess that the pads were discounted to Rock Auto for excess returns, or were just old and the paint got brittle, or something similar, so this could happen to someone else. It's embarrassing to "scrich, scrich, scrich" up to a bus stop full of people, not really sure if they're looking at the Z or the noise.

You're right, it's not completely gone. It starts kicking in at about 3-6 inches of vacuum and gets full at about 11 or 12 depending on the distributor, by FSM numbers. Back to WN, it's funny that someone who hasn't checked that their timing works right is calling someone else an idiot for putting an inline valve in backward. Just sayin', maybe the frustration is misdirected. :devious: I like to pick on people who call names... p.s. Interesting side-note - my 76 280Z didn't even use the vacuum advance unless the car was in 4th gear. It actually has a solenoid valve on the vacuum line, activated by a switch in the transmission. Weird.

What brand/kind of tires did you get? Maybe the old cracked ones were of higher initial quality. If the rims with old tires were balanced, then the new problem might have come with the new tires.

Under heavy load, with the throttle open, the vacuum advance goes away. Vacuum advance comes in to play at partial throttle openings when the intake vacuum is high enough to pull on the diaphragm. You'll feel more "pep" at a partial throttle but probably not much when climbing hills or accelerating quickly. Check your mechanical/centrifugal advance mechanism. Easiest is with a timing light and the vacuum advance hose disconnected.

I need to learn how to use them emoticons. A lot of good information here anyway, as a result. I didn't know that the 260Zs were using EGR, it didn't show up on the Federal 280Zs until 77 or 78. I guess the EFI let Nissan back up a few years. Plus, the whole argument about not needing the switch if you don't need the extra distributor pickup becomes less relevant since the switch is used for EGR. No harm, no foul:beard:

I think that you're mistaking my quest for clarity and knowledge with a challenge to what you're saying. It's not. It's exactly what I wrote and the picture I posted. mousemedic said "only", I showed why he might have said that. Now, you have shown, with your references, that there's more to the story. This is the internet. The best way to get someone to believe the point you're making is with examples and references. Without those, how do you know if anyone really knows what they're talking about? And how do you explain it to someone else? "A guy from the internet said it was so". Thanks for the link to the EC section. Now we're learning.

Just trying to help people get on the same page. In this case, page EE-27 of the 1974 FSM.

It's hard to figure out what exactly you're describing. I don't even see the "wire in question" in your first post. You can test the headlight switch directly by taking the plastic cover off of the top of the steering column and measuring voltage in and voltage out at the switch. The wires and their soldered attachment points will be exposed with the plastic cover removed. Measure from the power input wire to ground, see if you have battery voltage. Turn the headlights on and measure the output wire, you should see battery voltage. If you have both of those, then move over to the dimmer switch on the turn signal stalk. That is the ground for the headlights, one for low and one for high. It's common for the dimmer switch to get gummed up and not provide a good ground for the high and low circuits, either one or or both. You can spray contact cleaner in the dimmer switch and work it back and forth sometimes, to get the headlights working.

mousemedic might be going off of what is said in the 1974 FSM. Kudos to him for checking the factory source. It says that the automatic only used the water temp. switch to switch pickups in the distributor. Of course, 1974 is the year of change so it wouldn't be a surprise if the manuals had the switch also, like the 280Zs do (auto and manual), or they added it to the manuals when they went to the big bumpers. To correct one thing in mm's post though, the timing is advanced when cold, then goes back to retarded when warm. My guess is it's another idle speed increaser, like the AAR. It's described n Engine Fuel, not Emissions. It seems like a lot of technology for an unexplained effect.

Pretty sure that's not the proportioning valve. It's only purpose is to show a failing brake system, by pressure differential between front and back. The proportioning valve is in a different location and does not have an electrical switch inside. You're right though, that is could be a source of brake light problems. I don't think it needs replacing if it's triggered though, it automatically re-centers itself when the pressure differential is fixed. The brake check warning lamp relay under the passenger seat could be involved in a brake light problem also.

You might be able to break the seal by knocking it on the side with dead blow or rubber mallet. It would help break up the rusted bolts also. Tapping back and forth would let any PB Blaster, etc. works its way in to the bolt holes. As Walter said, a drill will probably walk on off the bolt end and in to the aluminum housing. You might also put the thermostat cover back on the top and use it as a lever. I've had one that I drilled and removed but ended up with the through hole enlarged, and another that I was able to knock loose and work back and forth to get free. The rust from the bolts fills up the through hole in the aluminum but will come out as powder if you can get it moving.

I saw in your previous post that you've put a new exhaust system on. They will look under the car with a mirror for a catalytic converter if the door tag says it's supposed to have one. Just a heads-up for you. As far as the idle emissions spec. you'll get multiple tries to get it right. No fees until you pass.

Engine RPM is mainly controlled by air supply. Which is mainly controlled by the throttle body. The AAR bypasses the throttle body when it's open, that's why it was a good place to look. Leaking hoses can let air in that will increase RPM, as long as there is fuel available, so any hose attached to the intake system should be checked. The PCV system can let air in from the crankcase, if there is air leaking in to the crankcase. For example, through the dipstick tube, valve cover gasket or oil fill hole. Can you get the idle to hang high while watching the engine with the hood open? A weak throttle return spring or sticky throttle blade can hold the idle up. That sounds more like your problem since the idle eventually drops down. Watch the throttle blade lever and see if it's dropping back to its stop quickly. The AFM just responds to the air flowing through the throttle body, so it's unlikely that it would cause a high idle.

We're in to the minutiae now. My main point was the old adage "don't believe everything you read." You could also add "make sure you understand what you're reading." Racer Brown's article can be interpreted in many different ways. I don't see anything in it that can be used to decide if the #3, #2 or #1 hole is "better" for a new chain and sprockets, on a stock engine. Cam timing retardation happens, but retardation from what starting point - "optimum" (subjective, and maybe Nissan missed the retardation effect) or already advanced (because Nissan engineers are no dummies)? After siteunseen has it done and reports back, we can discuss the relevance of "butt-dyno" results,and what oomph means. Site, maybe you could do some 0-60 runs to give some measurable results? And thanks for the opportunity to hash out some new topics on your thread. Good luck with it. By the way, it seems that Nissan gave up on the three adjustment hole idea in the later ZX L28s. It's not mentioned in the FSMs anymore. Probably caused too much time-wasting internal discussion among the engineers.

Use a punch to drive them through and out. It's a tapered pin, no threads on the inside only on the end where the nut was.

I guess we all get something different out of the same words. I actually left out the words that got me going, they are below. Racer Brown is suggesting that the original design is wrong, or that the Nissan engineers missed something. Statements like that just get me wondering how the writer came to conclusion, and in this specific case, it looks like a guess. Cam timing is one of those things that's hard to mess with, without risking damage, and hard to measure results without a dynamometer. Even measured, you have to know what you want before you can say it's better or worse. Do you want oomph or high RPM HP? It's all good conversation, didn't mean to offend with my engineer comments. Scientists are even worse. Here are the statements that offended me - "Datsun chains are quite long, about 42 inches in circumference, with 110 links, which means that keeping the valve timing exactly right at all times, is nearly impossible. It is therefore better to start out with a slightly advance camshaft - say by 3 or 4 crankshaft degrees - because there is no way in the world that it can be kept from retarding itself as the engine is run, particularly at high engine speeds. This is also the reason for the three different timing marks and three different dowel pin holes in the Datsun camshaft sprocket; they make provision for advancing the camshaft in 4-crankshaft degree increments, but they make no provision for retarding the camshaft. It does that by itself with no outside help required!"

Here's one. His writing implies that the three holes are for power band adjustment, if you're going to run at high RPM. If you want to, they are there for your pleasure. Don't worrying about retarding the cam timing, it's self-adjusting!! Just rev it up higher until the cam timing is where you want it! "because there is no way in the world that it can be kept from retarding itself as the engine is run, particularly at high engine speeds. This is also the reason for the three different timing marks and three different dowel pin holes in the Datsun camshaft sprocket; they make provision for advancing the camshaft in 4-crankshaft degree increments, but they make no provision for retarding the camshaft. It does that by itself with no outside help required!" Another obvious follow-through on this discussion is that retarding your cam by installing it off one tooth and using the holes to dial it in, still retarded, will give more high RPM power. Move the power band higher. Maybe the racers are already doing it, it's easy, and cheap. A little porting work to let the engine breathe, slip the cam chain a tooth, and you're making cheap, easy HP.

His words (Racer Brown's) imply that he knows what the Nissan engineers were thinking and why they had two adjustment holes. He doesn't offer any evidence for retarded cam timing, using a good condition chain and sprockets though. He just offers an idea of why they might be there. The FSM explains in clear times what they're for - adjustments for wear. For the record, I have worked with many engineers and know that passing courses and getting an engineering degree is no guarantee of logical, clear thinking. To the contrary, I have met many engineers who assumed that because they were engineers, that their thoughts, on any and every thing, must be correct. "I have an engineering degree, I must be right." As I said, great for conversation, but don't spend your money on what's said until you see the evidence that it's true.