Daeron

New Poll: What does you Machinist mean, historically speaking, when he says "next week?"

What the heck... WOW this thread kinda budded and thrived over the course of today, that was unexpected... "divorced" lol. I only posted about the EGT gauges to get sappy and talk about how I liked the dual needle sweep, because I'm used to seeing it in the old fast cars from when I was a little kid... (and I thought I helped to illustrate the low resolution obtainable from one of them, not contradict it) but now all of a sudden... carputer? I don't think I've bumped into that term yet, although the concept has been on my mind for nigh a decade now... must research soon, thank you!

IIRC you start testing for voltage at the injectors and work backwards.. I am pretty sure the positive voltage to the injectors is present at all times when running, and the ECU switches the ground.. If so, you would start by making sure you had the ECU thinking it was running (read EFI bible) and checking for positive volts at the injector plugs. If the juice is not there, work backwards towards the resistor etc until you find the problem. Thats a summary pulled unpracticed out of my mind from practically memorizing the EFI bible a couple years back. I may be wrong on a few finer details, I may be skipping stuff, but its ALL in the EFI bible. Don't just read the first 35 pages, the testing section is where you learn how the switching in the system works and how to check what, when such and such symptom occurs.

dropping resistor. That what takes the 12VDC and drops it down to ~5VDC (?something like that) for the injectors to fire. EFI bible ought to show you the way. Its bolted up near your hydraulics and brakebooster.

This car wants EGT sensors, not O2. Thats my gut feel at least. And not to contradict what tonyd said about analog gauges, but to me one of the [pinnacles of having a nice, old skool setup is a dual EGT gauge with needles that sweep against each other : http://www.aircraftspruce.com/catalog/inpages/westduals2.php (you can see what he meant about the difference between 1285 and 1320)

How DARE those filthy euros take advantage of our fragile economic infrastructure like that!!!!!! /sarcasm off

that was around my guess, but I was hoping for something a little lower out of sixth. still..... OOooompy.

Wow.. Sir, I am not a fan of HID headlights in the least, and even less a fan of retrofitting them into an older vehicle (personal tastes, I hate the light) but that was a NICE job! Quick, easy, cheap, and effective!

+1000, I was going to suggest the same thing. Have the E31 head taken to a machine shop, have larger valves and hardened seats installed, and have that head prepped. Despite my post count or any other impression to the contrary, I am not exactly that hands-on experienced, so I use this engine calculator as a crutch and let it do all my thinking for me: http://www.ozdat.com/ozdatonline/enginedesign/ I can not certify it is dead accurate, but according to that a piston with zero dish/dome yields just under 8.5:1 on a stock P90.. and a zero volume piston equals 10.1:1 compression on a stock E31 head. If that is a little high for your tastes (sounds just about sweet to me, if you find the right cam and put a nice distributorless ignition on it but I don't know what you really want to bother with) then you can always have a little meat taken out of the piston, but I would recommend doing that not in a circular, symmmetrical fashion, but rather offset to the valve side of the piston. This gives you a 3-dimensional "peanut" shaped combustion chamber that ought to work, just fantastic. Whatever you do, the E31 is probably your best bet for an easy, high performance NA head. The biggest reason it isn't talked about so much these days is because they aren't incredibly easy to find, and alot of the heads that ARE available fetch a slight premium because they are useful in 240Z class restricted racecars. In other words, the E31 head is only ever written off because its hard to find; if you have one, then its a GREAT head to work with once you get it to breathe with some larger valves and appropriate port massaging.

Whats the final overdrive ratio on the transmission in top gear??? I am beginning to wonder about top speed with a VQ, a six speed gearbox and 3.54 rears....

What about a weld-in patch for the spot weld area above the rear quarter panel windows that always rusts out?? Maybe thats a *little* ambitious... What about a lower rocker panel, ie, below the door? Is that already available? (I don't pay too much attention to sheetmetal and whats out there...)

tubeframe??

Meh, as long as its got a relatively low mineral content...... I *do* like the switch with the elite weapons-grade safety cover though. touche..

SHHHHHHHHHH!!!!!!!!!!!!!

you don't need fuel pressure, you just need to keep your float bowls full. Have you checked for proper function of the timing advance mechanism?? electronic ignition is REALLY the #1 A-1 swap o do on a points-sparked Z.

THAT!!!!!!! is what a well-flared 240Z looks like!!!!!!!

There is no factory starter relay. There is a main EFI relay that clicks on with the key, and if I am not mistaken clicks OFF in the START position and back on in RUN. The problem lies in eventual buildup of resistance in the solder joint and wiring connections in the starting circuit. In the end, you are left with a vehicle than cannot communicate enough amperage at 12VDC to get the job done at the solenoid. It puts 12VDC there, enough to check voltage.. but not enough to even push the solenoid contacts together. However, this minimal amperage is MORE than sufficient to power a small bosch four prong relay, which can switch battery power to your solenoid terminal. You basically have a wire coming off of your pushbutton switch, going straight to the starter right?? It doesn't matter if you hooked up that wire from the EFI relay or from whatever other 12V switched power source. What matters is that you get 12VDC to the starter with the key in the ON or START position. Relay amperage doesn't really matter, I don't think it even sees 10 amps. What I would do is get a 30 or whatever amp relay, and protect the circuit with the fuse you add. Start with a 10 amp, and if that doesn't blow then your fine. You could step down to 7.5 or 5 and see if that blows under normal use.. but 10 is sufficiently small to be safe, and almost certainly more than enough to start it.

I am virtually positive that the relay has nothing to do with the starter circuit on our cars. I had this identical problem on my 87 Subaru.. It would frequently give me a click, click, click, then finally third or fourth try--Start! eventually the starter died, and I replaced it with a JY unit. The next day it was total DOA again, so I had to use the screwdriver to get around. I solved it by ADDING a starter relay. I always had 12V to my solenoid wire when I hit the key, but it still wouldn't engage the solenoid enough to get it to perform its switching function.. so I put in a four prong bosch relay, with fused power tap straight off the battery, signaled by the original solenoid wire. The output wire of the relay went to the starter solenoid terminal, and I never had a starting issue again. The relay took the place of me and my screwdriver. I can't see what (in your situation) involved the main relay; but I may be getting my wiring harnesses confused, and your 74 (with its interlock system) may well be different from my 75 and ITS interlock system. Personally I would far rather be using a relay on this circuit than a switch in the cabin... but that is an argument to which there IS no end. I would say it goes without question that adding the relay is the safer, "better" route, but Nissan switched the load through the cabin so it is hard to argue that a pushbutton is "unsafe." Personally I don't care much for it, but don't have a problem either... I would simply never install one into one of my cars unless I also had a bluetooth wireless "key" like late model nissans do.. and when I did, the pushbutton would operate a relay under the hood

Excellent post, but I have to correct your mathematics; its an easy slip-up, and I had to triple check myself to make sure you were wrong and I was right. A core 10"x24" has an area of 240 sq inches. You would therefore be looking for an opening with an area around 40-120 square inches, which would vary from 4"x10" to say, 8"x15". 5x12=60 sq inches, 1 3/4x4=7 square inches!!! You forgot squaring

Bah! If I had a nickel for every time I was thankful that my Z let me take me keys out whenever I wanted, I could get her painted. If I was REALLY worried about it, I took the keys and locked the doors leaving her running. Yah, I suppose the rare occasion that I actually locked the doors with it running I ran a risk of something catastrophic going wrong and not being able to jump in real quick and cut the key/pop the hood/whatever.. but nothing ever came of it, and THAT isn't a very common scenario.

Just be certain of a few things.. I would imagine that blue's tech tips page on atlanticZ's website would have the reference material, if not directly there on the page then in the EFI bible available for download there... First off, make sure you get a Throttle Position Switch, not a Throttle Position Sensor. One is a pair of switches, one for "Idle" position, one for "WOT" position, and no contact on either indicates "Cruise" to the ECU. The TP Sensor is more like a volume knob, sending a variable signal indicating how far the throttle is open. Our L-jetronic system uses the older, switch type. Second, make sure that the switch operates in the right direction. (Although some wiring changes *should* be sufficient to rectify this potential issue.) Third, make sure the switch open/close points are relatively close to original. If all that works then it ought to be A-OK.. theoretically you could replace the TPS with a two way switch run on the fly by the driver in the cabin and it would FUNCTION.. you just run the risk of going lean or rich when you fail to adjust the switch acccordingly.

balance tube?

There was also a "Nissan 2400 OHC" OEM nissan valve cover that looked alot like our stock "Nissan OHC" covers IIRC, its probly all in the CZcars.com thread Edit Wow the difference in those two NISSAN blocky valve covers is subtle...

Don't forget to check valve adjustment.

That makes me think...... The city of Lake Worth, Florida (supposedly? I verified it somewhere, at some point, but I can't place 100% confidence in this factoid) has the largest community of Finnish persons outside of Finland in the world. I've known lots of Finns and always found them to be exceptionally pleasant, enjoyable, and downright friendly people.. but if any of you folks have relatives over here that you should happen to visit, West Palm Beach is right next door to Lake Worth, and you guys are more than welcome to drop me or my brother (cobra_tim) a line if you'd like to visit and talk Datsun. Or, if you could use a Datsun friend state-side and know someone local.. Just putting the offer out there!