Captain Obvious

And I forgot something else about the ebay locks... The ebay locks do not have the "return to center" feature that the stock locks have. Your stock locks have two springs that balance the lock position to the middle when you aren't turning the key. The ebay locks have no such feature. They will stay anywhere you leave the key. Not a big deal, but I kinda like that return to center feature of the original locks. I'm not crying about losing it, but I do think it was neat. Apologies for the multiple additions, but it's been a while since I messed with my locks and this stuff is coming back to me piecemeal. Something else I forgot to mention. You said: I'm not positive, but I believe the lock cylinders themselves are identical right to left. Only the arms are different. So if you find two old usable locks, you can mix and match the arms from your original set to get a R and a L.

Not so definitive... My PO proved that the ebay locks are an option. They are clearly not an easy drop-in option, but they are an option if you run out of other simpler avenues. In my limited lock work, I've found that there are two things that commonly happen with the stock door locks. First, the pot metal cam on the back smears out and you can't get enough travel to actuate the lock. This is the problem you have, and you can clearly see this by pulling the retainer clip off the back and getting a good look at the cam and follower. The other thing that happens is that the lock cylinder and wafer tumblers wear on the inside of the lock. As this wear occurs, the lock becomes finicky and eventually gets so bad that the correct key will no longer turn the lock. This wear, unfortunately, you cannot see without taking the lock apart and that means dealing with the crimped on chrome face cap attached to the outside face of the lock assy. Your sticky stock locks were probably a combination of worn cylinders and wafers/springs that were corroded in place and stuck in their slots. The WD-40 hopefully freed up the tumblers, but it won't do anything for the wear. If you're going to drop in a different pair of stock locks (or a pair of ebay locks), you'll have the multiple key situation. And if you decide to have the locks keyed alike, or do it yourself as I have, you'll get the opportunity to evaluate the guts for wear.

I forgot to mention that I also see that you have the pin 12 altitude compensator switch connection (which makes perfect sense since you're in CA). The non-CA cars (like mine) do not have a contact in the number 12 position on the harness side.

It's not just the tilt. It's the tilt combined with the fact that the front carb has the bowl on the uphill side of the nozzle while the rear carb has the bowl on the downhill side. If both bowls were on the same side (either side), then the tilt wouldn't mean squat.

And if the cam and follower stuff doesn't make sense, let me know and I'll snap some pics. I've got both types in the shop but haven't taken pics of that detail.

Yes, the longer arms came with the significant door redesign in 77, and yes, you are right in that the ebay door locks will not easily work on your 78. However, the problem isn't just the length of the arm. It's also how the arm fits onto the back of the lock cylinder. If it were as simple as the arm length, you could just move your old arm over to a new ebay lock, but you can't because it won't fit. In fact, most of the auctions for the door locks include some generic BS note about "You may have to move your arm over from your old locks". But it's BS because you can't! The problem is that the older style locks have a different shape cam and follower on the back of the lock and they cannot be mounted onto the newer ebay style locks. You're OK if you have a pre-77 Z because you can just use the new arms on the new locks, but the 77 and 78 guys are left a little cold. Here's what my PO did... Cut the new arm from the ebay lock in the middle. Cut the 77-78 style arm from the original locks in the middle. And weld the two of them together to make a 77-78 arm with the new ebay style cam follower hole. It wasn't a great welding job, but it's certainly strong enough. It's ugly, but it's behind closed doors. Pun intended. Remember though... I'm not a locksmith.

Assuming the car is an auto trans, you're fine. The reason the contacts don't match up perfectly is that there are a couple locations that aren't used when the car is being driven, but are used for diagnostic purposes. On the harness side for example... Pins 20 and 21 on the wiring harness don't make any connection to the ECU, but can be used to verify the functionality of the fuel pump signal and cold start system respectively. And on the ECU side for example... Pins 11 and 26 are test output locations for the injector signals. They aren't used for anything when the ECU is in the car, but they could be probed to see what the injector drive signals are doing. I don't see anything wrong with what you have there.

DRBall, Is the .pdf that black gold man linked to the same one that you have, or do you have something different?

I'm interested in a copy of this... Is there a place you can just upload the file? What format is it in?

Gotcha. That's a good point.

Bummer. I don't know what the offending ingredient is, but in thier FAQ: Pine-Sol® Ingredients, How to Use Coupons & Other FAQ's

Yeah, that's why it seemed like the same thing to me as looping the heater hose. Sure, you'll get some convection currents in the air in the box where the core is, but that's gotta be negligible. Makes me hope you were right about this: I agree, and based on the empirical data of "we don't hear from lots of stock owners with overheating problems" I would guess they did OK with the margin of safety. Still makes me wonder if I may have complicated matters with my fancy schmancy heater flow valve...

And at the risk of typing a bunch of stuff you knew already... There are two things that control how much fuel will be pulled in. First is the gap around the needle, and the second is the speed of the air through the venturi. The bigger the gap, the more fuel. Simple. The faster the air through the venturi, the more fuel. Not as simple. The trick to the damper is that when you punch it, the engine sucks a lot more air, but the piston will not rise instantly because of the damper. Because of the slowed damper rise, that "lot more" air has to funnel through a smaller opening and Bernoulli says that will cause a lower pressure. That lower pressure pulls more fuel in even through the smaller neeedle gap. Once you have reached steady state, the gap is the only thing controlling mixture, but in transition if you slow the piston rise enough, you can actually create a transient rich condition EVEN RICHER than the steady state will be. That's the simplistic beauty of the SU design!! So in short, a thicker oil will slow the damper more which results in a richer transient mixture.

Counterintuitive as it may be, it really is true. There are lots of sources to cite, but here's two that should carry the most weight around these parts: First is from Skinner's Union's themselves: SU Carburetters The S.U. Carburetter Second is a snippet from the Datsun factory service manual (1973 pg EF-9):

Actually it is stagnant. There is an air intake control flapper door on the input to the blower motor that selects either outside fresh air, or recirculated. You get that air intake door into the recirc position with the fan off, and it's dead stagnant (or at least as stanant as your sealing foam on the door will allow). I don't know about the 240s, but it's easy on the 260 and 280. Without A/C, if you move the top lever (the "AIR" lever) to "OFF" this will put the air intake door in the recirc position. No fan, and you're stagnant. (260 FSM BE-46) (260 FSM BE-48) And if you do have A/C, you're running in recirc any time you have the lever on "A/C" or "REC HEAT". Put the lever into either of those two positions with no fan, and you're stagnant. (260 FSM AC-6) (280 FSM AC-6) Good point about the coolant flow valve. I have to remember that my modified flow valve provides pretty much no resistance when wide open. Something I should probably keep in mind... When wide open, I bet I'm sending a lot more hot water back to the water pump than stock. I'm going to consider adding a restriction to that line. It's not like I need more heat in the interior. I get plenty. Between that and the fact that my PO took off the heating pad under my AAR, I'm thinking I should install some sort of small thermostat bypass just to make sure I get some flow into the thermostat housing to keep the thermostat up to date with the rest of the engine. Thanks for the help!

Here's what was suggested the last time we were talking about pin21: "a" isn't gonna happen without the ECU even making connection, so I'm sticking with "b".

Excellent. As stupid as it seems, there's a lot to be said for little details like this. Snappy, positive, predictable operation. Satisfaction in liking the way it works every time you use it. Corny, but it's the little things...

I can't even figure out what you're trying to say. What does ebay have to do with anything? There's a guy on HybridZ (FricFrac or something like that) who does a lot of work with the FI harnesses. Why don't you just buy one from him? I think he offers everything from connector "kits" to turn-key harnesses. S30 and S130 Wiring Harness repair kits. You NEED this if you have an L28E or L28ET! - Parts for Sale - HybridZ And I believe he does have some of his stuff on ebay... Is that what you're talking about? Are you saying that you're planning to actually SELL rebuilt harnesses on ebay? If so, that's not a "hobby", that's a "business".

Wade, Don't know about your ZX, but on the Z The cold start valve is not tied into the ECU. I believe you are referring to the mysterious "pin 21", and if that's the case, then remember that while there is a wire going from the cold start valve to the ECU connector, that signal does not actually make it inside the ECU case. That pin location is not populated. No pin at all, just a blank hole. That signal makes it to the ECU connector, but it doesn't go any farther than that. Would be interesting for you to take a look at your ECU and find out if your ZX populates that pin location. Maybe they started using it in later years? :bulb:

Haha! Yeah, I remember those times as well. Don't remember which family car it was, but I remember Dad turning the heater on full blast in the middle of summer and then trying to explain to me why. As for the looped heater tube, I really don't think there will be much heat rejected by the core in completely stagnant air, but granted, it will be non-zero. Same situation for the resistance to flow... I suspect there's not much, but, non-zero. Oh well, just curious if I was missing something simple and there really was some big reason why those two situations were different.

Haha! Ya think?? Makes me wonder if ads like that help or hurt our Z community. Stuff like that ad irk me because I think it makes the collective "us" look like crackpots... [/Threadjack]

Well, if you got 15K to spend on a Z, you could buy this beauty currenty for sale in NYC! 1974 datsun 260z with low miles For that money, I think I'd rather have the one from San Diego... :stupid:

I also believe you have the flow direction through the carbs going the wrong way in Figs 1, 2, and 3. Not sure about the direction in Fig 5... I don't know what would happen there. So about looping that heater hose as shown in Fig 4. I understand the concept about it short-circuiting the radiator and sending hot coolant back to the water pump inlet, but here's my question... With a completely stock setup, how is that any different than driving around with the heat selector control slid all the way to HOT and putting the air selector lever to OFF so there isn't any air flow through the heater core? You're doing the exact same thing, right?

If you want something self contained to the console, there ought to be something hot at all times going to the flasher switch.

It's supposed to be hard to lift the pistons. 15W40 is higher than the manual recommends (and higher than I've had success with) but if it works for you, then go for it? Are you blowing black clouds on acceleration? Are you fouling the plugs? Is your gas mileage really low, say below 17 mpg? If your answer is "no" to all of the above, then are you looking for something more than that?