Barrel_Ball

And that's where the problem is - I found these at my local junkyard, and this is the first 70's XJ I've seen in almost 2 years. I can't see myslef finding an XJ6 tach laying around anytime soon, unless it's a late 80's XJ, in which case the gauges are different. I could try and use a pot to adjust it, but then I'd have to play by ear, or use a ECCS analyzer with its digital test tach (which somebody I know has). 0-10K was it? I guess I could look into that (I hope Active Electronics is open on Saturdays).

This is the circuit board of the tach. That big striped component is the resistor. I found out it's a 4.9k Ohm resistor, and that I have to either replace it with a 9.8k resistor, or find a second 4.8k, and attach it parallel to the first one to double the resistance (at least, I think that's how it works). Pretty simple, component wise. A diode, a resistor, a capacitor, a controller chip (I think), and what could be a signal converter. No potentiometer to adjust for calibration, which kind of makes adjustment for accuracy hit-or-miss, but I could just solder one in, I guess.

Okay, after a couple hours of research, I came to conclude that in order to get this tach to work with my engine, I pretty much need to replace the resistor with one of double the value in order to doulbe the pulse width, and time-constant (or so in reverse to what the source said as they were decreasing resistance to get a 4 cyl tach to work with a V8) to make each of the 3 pulses per rotation (I think) be there long enough to amount to two pulses (of I believe 6 per rotation on the V12), turning the 12 cylinder tach into a 6 cylinder tach. This is the only real way I can think of doing this, as it doesn't have a calibration pot like most others seem to have. I just gotta find out which one's the resistor - It's a tiny 70's circuit board with five components soldered to it, so It shouldn't be that hard. Thanks for the tips, everybody. It helped.

Does anybody know the sweep on the factory Z tach? If it's 270 degrees, then I can just take the innards from that and retrofit than into the Smiths housing. Like I said, dead-on accuracy isn't my prime goal at the moment, as I can just get some new gauges in the future when I get the cash for it, I'm just after cosmetics in that department for the time being. I'm sure I can find another 280Z tach kicking around somewhere (I knew I should've taken a few more things from those parts cars) and see what I can do with that. Just minor uniqueness, is all.

Well, I'm just doing this as something different. Dead-on accuracy is great, but those aftermarket units get really expensive for some reason. I would like to use aftermarket innards with these faces and housings if possible, but I just want to see if I can get the stock Jag hardware to work on my car - My Z is moreless an experimenting testbed that's also my prideful toy - This is why I'm asking if there's a way to make a V12 tach work properly on an L6 engine's ignition system. I know there was an old aftermarket tach I had with a pile of parts that had a switch on the back for 4, 6, and 8 cylinder applications, but I gave it to a friend to use on his project. I know there's a source of reliable info out there, it's just a matter of where to look for it. And yes, NES for the win.

Today I went to my local Pick n' Pull, and found a '77 Jaguar XJ12 L sedan, so I took the gauges. These would be the electrical Smiths units, dunno the exact measurements, but they look like they would fit into a Z dash with some custom mounting of sorts. Sure, I could just go and use aftermarket gauges, but I don't feel like it - I like the look of these guys better. I know the speedo would probably work simply with the right gearing. As for the other gauges, I think I'd need to nix my clock, and then make another mount for the fourth, since they're not combo units. However, as far as the tach's concerned, I'm not sure how I'd get it to work. It's made for the V12 engine, but I'm running an L28ET in my car. Is there some sort of way for the tach to receive half the pulses as it was intended to and still read somewhat accurately?

Wow, finally I find a thread like this. I hope these aren't too big. By the way, the last two are a 240SX with a 280ZX front end grafted on.

Geez. now I wanna rebuild my old L28 using an M103 head for a crossflow setup. I've seen a few around the junkyards, just not lately. But even the M103 looks like a mean setup. Come to think of it, the M103 closely resembles the Nissan RB30E, now that I look at them side by side. Wierd...

Okay, now I know that 3 of the ignition plug wires have a purpose, the one yellow/white wire going to what I think is the signal lead on the ignitor, the other two being a ground and a 12v switched (not 100% what that means), but what becomes of the other 3 wires? just leave them hanging? Pictures help, but pictures with more convincing angles help even better.

Geez, and here I was planning on swapping a set of '77 doors onto my '76 with a slight modification to the striker pin on the body. Since my driver's door just won't close unless you slam it hard.

I'm after a set of Enkei 92 mesh wheels, preferably the 15x7 +0 offset wheels that I see once in awhile on 240sx's. If anybody's got anything, PM me.

I figured I'd post what I'm putting together. It's in pieces due to the block, head, and crank still being at the shop until I get it paid off, so I'll just list what I intend to build to start off. Engine: '81 L28ET - .050mm bored F54, rebuilt P90, .050mm oversized pistons, stock crank/rods, stock valvetrain, 2+2 flywheel. Intake: '76 N42 non-EGR manifold with Turbo TB. Turbo system: Stock T3, Ford Probe GT IC, Rx-7 TII BOV. EMS/EFI: Stock '82-'83 ECU/wiring harness/ignition, stock injectors. Exhaust: 2.5" downpipe, 2.5" free flow pipe, will decide on muffler later. Power: Shooting for 200-250HP at the wheels. Not sure what that'll make tourque - wise.

This thread reminds me of my english classes all over again, except it's actually entertaining, this time around. I seem to have a tendency to type too fast and screw up spelling too, or just type a completely wrong letter by reflex, or two of the same letter when I shouldn't, but at least I try to correct it before posting. Windows Live Messenger is to blame for that.

First two I had are a '72 (I think) Flared out 240 with a crushed in roof, and no engine in it and a '76 280 2+2. Both of them were parts cars, the 2+2 I used for the engine and tranny. The third one is my running car,which is a '76 2 seater, and I recently got a '77 2+2 parts car. Wow... I went and bought four Z cars in the course of a year... I just realized that I scare myself, sometimes.