Zed Head

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.

No offense Leon, I didn't even notice who posted the thread. I've read the article before and wondered then where this guy got his ideas from and decided at the time that it was mostly theorizing. My point was to take it with a grain or two of salt. It's good for understanding what might happen, but short on showing what really does happen. Great seed material for more discussion.

The Racer Brown article is full of conjecture and guesses. A great place to start for experiments and good ideas to be aware of, but there's no facts to back up the claims. It looks like someone just writing down their ideas of what "must be" happening. The two extra holes are most likely there for chain wear as the FSM describes.

The clues do seem to point to exhaust. Seems like a good muffler shop would know what a clogged exhaust system sounds like. The gases don't pulse the same coming out of the pipe. Might be worth having one take a look. Find an honest shop, of course. The lack of vacuum advance could be due to the lack of intake vacuum, which could be related to a clogged exhaust system.

Could be the BCDD. It's purpose is to cut fuel flow and reduce intake vacuum, through a throttle blade bypass channel, above 2800 RPM and 10 mph, under throttle closed deceleration. It's mounted under the throttle body and has a power wire connected. It's the weird looking thing with the rubber boot on it. It's an emissions device so is described in the Emissions section of the FSM.

Kind of stating the obvious aren't you? Experiments that yield measurable results are part of the method. So if someone (the mechanic in this case) has advanced the cam to #3 and felt more "oomph" then they've applied the method, and have knowledge. The discussion can revolve around what oomph means, but if your mechanic has done it and knows what happens, then you can only go off how well you trust him. If he was my mechanic, I'd ask him what he means by "oomph" and what I might lose by doing it - peak HP, for example, if what's described above is correct. If he's just working off internet rumors then you and your engine become the experiment.

Pretty sure that I've seen similar referred to by one of those guys who seems to know a lot, on another forum. One of those old tricks. It's interesting though that people will spend lots of time and money to get their cam set perfectly to the cam builder's specs., using a degree wheel and adjustable timing gear, but will throw an extra 8 degrees of cam advance in for more "oomph". Just an observation about engine tuning. Lots of mystery there, when it comes to cams. If you search around Hybridz, you might find some threads. I think that Tony D had some stories about cam timing tricks. If you're in the waiting room tight now and the question is what to watch on the big screen, the Euro 2012 semi-final is on in about 1.5 hours. If you're in to that.

I know that a lack of timing advance will reduce power, but don't know how much is not enough. Personally, I like to know what the numbers are so I have measured both vacuum and centrifugal (mechanical, centripetal... refers to same thing even though maybe not the right word) on mine. If you have the timing light on and rev the engine up until the mark passes the end of the scale, you'll know you have at least 20. You can probably eyeball it up to 30. Kind of hard to tell since "bog" is a subjective word. One man's bog is another man's hesitation. Plugged exhaust still seems like a potential cause also.

I believe that he's saying that his bushings are too small, not too big. Removing the liner would make it worse. Maybe the bushings are designed like the mustache bar bushings and need a "liner" and IK's are gone.

The vacuum source for the vacuum advance is what they call "ported" vacuum. The port to the hose is closed when the throttle blade is closed and open as soon as the throttle blade comes off of the idle position. So with a timing light, at idle, you might see ten degrees. As soon as you open the throttle a little bit the timing will advance due to the vacuum advance, then as you rev it, the timing will advance even more due to the centrifugal. If you want to test the vacuum advance completely separately from RPM, connect the hose to manifold vacuum. The timing will jump up as soon as the vacuum is applied and drop back down when the hose is disconnected. Leave the hose disconnected and rev up the engine and you can see how the centrifugal is working. If you want to get really specific and measure how much of each you're getting, set your static timing to zero (you'll have to bump the idle up to keep the engine running), then measure vacuum as described with direct intake vacuum and centrifugal by RPM (rev until it stops increasing). You have to set static to zero to use the timing scale, unless you have a dial-back timing light. Vacuum is typically about 15-18 degrees extra, and centrifugal about 20, depending on your distributor parts.

Hey FW, that's a good idea but I think that the AAR is on the fuel pump power circuit. So if he takes the wire off of the starter solenoid and holds the key to Start, he should hear the fuel pump run and the AAR should get power. It does take a little while to close. But that could definitely be part of the high idle problem.

The Z31 master cylinder might not really an "upgrade". It is used to increase pumping volume for use with calipers that require more volume, I believe. If you don't change the calipers, you'll just be increasing pedal pressure to get the same braking force. For what it's worth, the brakes on the 240Z are pretty good. Many of the "upgrades" are more for show, or perceived benefit (these have to be better!) than actual benefit. You might browse through the forums and read up on brakes before spending the money and time.

You can buy straight lines already flared with fittings from most auto parts stores. Then bend them to shape. If the car is down, remove the line and take it with you to make sure on the fittings. Use a piece of string to get length. One option. Why are you asking about master cylinders and upgrading to fix a holed line?

How long has it been running since you replaced the filter and pump? Did you replace them because of a problem? Spark plugs don't go bad all together at the same time, so plugs is unlikely. Timing almost never changes dramatically enough to kill the engine either, unless the distributor breaks. Sudden death is usually electrical, like a bad coil or shorted wire. A simple check for spark by removing a spark plug, sticking it back on the plug wire, grounding the threads, cranking the engine and checking for spark will tell you a lot. Or use an old plug if you have one and do the same. Are you still running points in the distributor or do you have electronic ignition?

How about more information? Is it a 76? Did it run before, or did you just buy a non-running used car with clipped wires that you need for work? Have you checked for spark and fuel? Those are the two basics to look for if it turns over but doesn't fire.

How to properly torque a bolt can raise a lot of discussion. I've read that anti-seize is not recommended on the threads of critical fasteners because it's too slippery and will result in higher than designed tension on the bolt. Bolts that turn without tightening are quite often in the process of breaking (think about the last rusty bolt you thought was coming out then it broke instead). I hope that's not your case. As for retorquing, I think that it depends on the gasket. Some are called out as "no retorque". Here's a description from an actual anti-seize manufacturer on torquing fasteners- http://www.saftlok.com/safteze/antiseiz/index.htm Another interesting page - http://www.mechanicsupport.com/bolt_torque.html Google brings up a bunch on just "anti-seize" and "torque".