Captain Obvious

Hardway, Have you got a link to the template you used to make your timing chain wedge? I looked for Californiaparts.net and came up blank. Better yet, have you got a copy of the drawing template you used that you could post here?

I just took a look at the wiring diagrams. The pigtail connectors didn't show up at all until 74 and the colors of the pigtails were never listed.

Take a look when you get the chance. I'd be surprised, but it would be good to know for sure. The connectors and short pigtail lengths didn't even show up on the earliest wiring diagrams, and then in the later diagrams, the connectors and pigtails made it to the wiring diagrams but the wire colors aren't noted on the pigtail. The engine bay harness has R and R/Y, but the pigtail colors aren't labeled.

TomoHawk, It's more complicated than that... In 77 and 78 they used the same short headlight pigtail on both sides from the bulb back to the engine bay harness. So while my 77 has a Red coming out of the harness on the pass side and a Red/Yellow on the driver's side, both sides are the same color (Red) after they pass through the three position connector to the short pigtail length to the bulb. In other words, the colors on my diagram above are correct. At least for 77 and 78. I don't know about the other years, but since there really isn't any difference in the pigtail for either side, I would be surprised to hear Datsun actually assembled different ones for each side in any year. Just no good reason to spend the extra money to build, stock, and use two different versions. Are the short pigtail wire colors different on each side of your car?

Thanks for the additional info on the MPV relay block. Those relays are a very common form factor and can be found pretty much everywhere. In fact, I think those are interchangeable with the Honda relays that I used when I did my upgrade. The one you pictured is SPST, but there's also an SPDT version in the same form factor (with the addition of one more pin on the bottom). The headlights only require SPST, but keep in mind for other stuff that you can get SPDT as well if necessary. Don't know if the MPV block has provisions for the additional pin, but just thought I would mention it. As for the starter relay... Do I think you really need a relay to operate a relay? The starter solenoid wart sitting on top of the starter draws more current than the ignition switch can handle forever. Eventually the contacts inside the ignition switch will burn up and you'll get intermittent starter operation. It's not absolutely necessary, but you'll eventually be replacing the ignition switch if you don't put in a starter relay. Maybe you and I will be dust by the time that happens to your car, or maybe it'll happen tomorrow (and I hope I'm not dust by then). I had already had my contacts burn up in my ignition switch once and didn't want to subject my new switch to the same eventual doom. I was in there messing around with wires and stuff already and just bit the bullet and did it all at the same time. Those are my thoughts. Hope that helps?

Just in time. Here's a redrawn version of the 4-relay option with emphasis on making it as reversible as possible. And in fact, it should be completely plug-n-play for your early 240Z. This scheme would work in the later cars as well, but it wouldn't be quite plug-n-play because you would need to do the under dash changes to make the fuses hot at all times and give the HI/LO switch the three states required. But since your early 240 is already wired like that you're ahead of the game! Who knew? So for an early 240, this should be plug-n-play, and "almost plug-n-play" for everything else: The only thing that makes it a little more complicated than the tradidtional 2-relay version is that you need to make connection to the driver's side headlight connector off the harness to pick up the R/Y wire. The traditional 2-relay version does not require any connections to the engine bay harness on that side of the car because it powers both relays off the right headlight side. I don't see it as a hardship though. You always have to run wires over there anyway to get to the headlight pigtail. It's one more connector and an additional wire. IMHO, I think that's a small price to pay for the benefits of fault tolerance and reduced voltage drops.

Sounds like a plan. One of the things that I like about having the fuses always hot and doing all the relay switching on the low side is that you need to bring one less wire to the relay block. You just connect one side of the relay coil to one side of the contacts. You can just daisy chain the R (and R/Y) wires to two connections on the same relay which results in less wires to the rest of the car. I like that relay block from the MPV. In another thread, there was some discussion of pre-existing relay/fuse blocks that could be harvested from other cars, but that one didn't come up. So the MPV block has spaces for six relays, all the same style? Any fuses in the block, or just relays? I would use one of the other relay positions for a starter relay to take the load off your ignition switch. If you're doing (or have done) the internal regulator upgrade, it's a convenient time to do the starter relay because the internal regulator leaves you with a couple unused signals that are needed to do the starter relay. Namely, hot at all times, and ground. You can re-purpose those two connections for the starter instead of the external regulator.

Great. And thanks for the early wiring diagram trivia. Earliest year I've ever personally taken a wrench to is a 74 but I like that trivia stuff anyway regardless of the year. So before you go cutting any wires... I still believe it should be possible to do a four relay option without cutting anything by plugging into the stock connectors. Especially if your car is already setup with fuses that are hot at all times and a beam select switch that has three states,: Hi to ground Low to ground No connect I know I said I would look into that a while ago (and didn't), but give me another day or so before you start cutting into your harness. I might be able to come up with something more plug-n-play.

Cool. If your car is wired as per the diagram from the 70 Owner's Manual, then you already have headlight fuses hot all the time. So I believe the answer to the question "With the set-up in my car (per the wiring diagram from the 70 Owners Manual), what do I need to do -- if anything -- to make my two headlight fuses always hot?" is "Nothing." I believe you're good to go in that respect. You can double check that by pulling one of the short pigtail headlight connectors off in the engine compartment and probing the R or R/Y wires while having the headlight switch in the OFF position. If your car is wired like the 70 manual, then the R and R/Y wires to the headlight pigtails should be hot at all times, while in the later cars, those two wires would only be hot when the headlight switch is in the #2 position. And I wasn't there when they designed the system, but I wouldn't be surprised if that's why they changed it in later years. It's less safe and less fault tolerant to have those wires hot at all times than to have them only powered when the lights are on. I'm not sure that's why they went away from that early scheme, but if I were designing the wiring for the car, I would have tried my best to never have anything hot at all times unless absolutely necessary. It's just safer when it's dead. So else can we do on the headlights? Are you OK at this point? Current round of questions answered? On Edit - And BTW - Thanks for culling the 70 diagram out of the owner's manual. I've got the whole thing in pdf, but it's much more convenient to have the wiring diagram pulled out and separate in it's own file.

Namerow, OK, I had a chance to look into the early years. First, You nailed this objectives of the modifications to the combo switch: 2. Make the 'Headlamp' fuses always hot However, I would make one change to the other objective (because the dimmer switch always did switch to ground). I would change the other objective to: 1. Make the Dimmer Switch switch to ground only when the headlights are on and not make any connection at all when off Second, I found a wiring diagram in the 70 Owner's Manual (not FSM, but Owner's Manual), and it appears that what's old is new again because the 70 cars are wired such that the above two objectives are already achieved. The headlight fuses are always hot, and the hi/lo select has three states: low beam connected to ground (R/B high beams connected to ground (R/W) no beams connected to ground (OFF) Third, I found the wiring diagram you referenced in the 1971 supplement manual and there are two diagrams in it. "Basic Model" and "Late Model". The "Basic Model" is wired like 70 version in that the fuses are always hot and the hi/lo beam select switches has three states. The "Late Model" is wired like all the subsequent years through 78 in that the fuses are only hot when the combo switch is in the #2 position (headlights on) and the combo switch always connects one of the beams to ground regardless if the headlights are on or not. Are we both on the same page so far?

Happy Canada Day!!

My unicorn and I will be there on Thursday July 16th. Late afternoon/Evening.

Namerow, Yeah, I wouldn't be surprised if there were some differences with the earlier cars and I probably should have accounted for some of that. Sorry for any potential confusion and I'll take a look at the older wiring diagram and see what I come up with.

charliekwin, The progress looks great. One thing though... I don't like the positioning of the lower spring on one of your rear brake setups. Looks like the spring is bent around the adjuster mechanism and that shouldn't need to be the case. I can't tell what the problem is, but if it's together correctly, everything should fit comfortably. I'm not sure why the one side looks weird: One side looks fine, but the other looks questionable.

Actually the stock system makes it impossible to do what you want to do. You can never have heated, conditioned air to the defrosters. Ever. Because of the design of the air flow system, the only location to ever exit conditioned air is from the "vent" locations. You can never have conditioned air come out of the defroster holes or the floor holes. Dash vents only. So while it would be relatively easy to bypass the electrical portion of the system and add provisions to make it possible to turn the compressor on regardless of the slider position, you simply cannot control the air exit position the way you really need it. And not only that, but when in the "DEF" or "HEAT" positions, the dash vents are completely closed off, so you'd freeze up your evaporator because you wouldn't have any airflow through it. So the best you could do is modify the electrical portion to allow independent control of the compressor and then put the slider in the BI-LEVEL position. That way you could get heated air on your feet and some conditioned air out of the dash vents. That air would mix inside the passenger compartment through convection currents and the end result might defrost the windshield. Might be better than stock, but certainly not as good as modern cars.

Bummer. I doubt there's any recourse from the company from which you purchased the wheels. You've probably had them longer than any warranty period, but it's not like they've seen any significant mileage. Bad enough that you could see it with the naked eye... How does that make it out of the factory?

Wow. I would have expected a bent axle or hub mounting plate if anything. A bad wheel? That stinks! Were those new or did you buy them used? Also, I assume they checked all four and only that one corner had an issue?

Back EMF works for me as well. I've heard it called lots of different things. Whatever works!

I can't help with your question about potentially different mechanical ranges of the heater valves between A/C and non-A/C cars, (so I probably shouldn't be in here at all) but in the spirit of the internet forum... All of the temperature control valves are mechanically actuated with a cable. The vacuum operated valve that you have as part of your A/C system is in series with the temperature control valve and it's purpose is to completely shut off all water to the heater core the instant you put the control lever into any of the A/C positions. Datsun is essentially saying "Nobody in their right minds would ever want to have warm air blowing on the windshield or floor while the A/C is on, so we'll just take that option out of the hands of the occupants. We'll just turn off all the water any time the A/C is on." I disagree with that design decision, but I wasn't there when they made that call.

Chas, Why do you think it would be necessary to open the "dimmer" relay to cut the resistance? That resistor is in parallel across the coil windings to limit the inductive kickback voltage and compared to the coil resistance, I bet it's a relatively high resistance. Like maybe an order of magnitude? It would "waste" a small amount of power when the relay coil is energized and be completely innocuous when the coil is off. I don't understand why you cant just leave the resistor alone and use it for it's intended purpose?

The form factor and pin-out should be the same for any manufacturer, but I can't attest to the inclusion of a diode inside to squelch the inductive kickback. Sometimes an internal diode available as an option from the manufacturer. In other words, sometimes you can buy the exact same relay in two versions... with or without an internal diode.

Hi Tamo, As SteveJ mentioned above, the polarity across the coil winding only matters if there's a built in diode inside the relay in parallel with the coil winding. I can't attest to the contents of all of the relays in that form factor, but I can tell you that the ones I messed with did not have a diode inside and the coil polarity did not matter. Also, on your sketch showing the starter relay, I think you swapped the C4 and C7 designations and the destination labels for those connections. I think what you have labeled as C4 "To fusebox" is actually C7, and vice versa. And one last thing... If you're doing an internally regulated alternator upgrade at the same time as the starter relay it is convenient because the original external regulator already has some of the connections necessary for the starter relay. In other words, the external regulator already has "always hot" and "ground" connections that can be re-purposed to power the starter relay system once they are no longer needed for the external regulator system.

Haha! I didn't even notice the mispelling until you mentioned it. Don't care. Either works. Mike, I would love to help out around here, but I'm not sure I'm reliable. I'll send you a PM and we can talk about it some more.

I've not investigated the differences between years, but I gotta believe that if you ported the entire system over it should work. I also don't know if there were any performance or emissions tweaks from one year to another. At that point in time, electronics technology was changing pretty quickly and I wouldn't be surprised if there were some changes between years. However, a perfectly working 75 system is still better than a questionable 77 system though, right?

Haha! Yeah, a couple thousand! Good luck at the alignment shop and here's to hoping that wobble was just the tire lettering.