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Finally, my first New Topic. (And 2nd New Topic in any forum LOL!)

I thought that G200W Piazzas were I-TEC with an optic distributor. (FYI - Optic pickups modules are available. And a "ref" disc. Info below.)

However, recently I have seen several "Piazza" G200Ws with reluctor distributors with mechanical (RPM) and vacuum advance.
All had I-TEC plenums (if they had any "name").
Is this typical? Common?

I expect most replies will be from NZ. In Oz we got the 4ZC1-t (with reluctor & mech dizzy).

I'm keen to know if the I-TEC with fixed-shaft optical dizzy was available back in the Piazza G200W 1981-1985 heyday.
If the reluctor with mechanical advance distributor was in the original G200W Piazzas, any idea how common or what proportion (if opticals also existed)?
And were they I-TEC ECUs? (That's a tricky one huh?)
And I assume all G200Ws had I-TEC plenums? (None were EGCI?)

I'm well aware that later morphing could have occurred - like ECGI or Turbo plenums, or even optic swapped for mech dizzy. That's understood.

Thanks in anticipation...


All the following is FYI pre-emptive ONLY! Desist now! Resistance s futile!:
Optic modules & discs. (Currently being investigated.)
The DOHC optic distributors are fixed shaft (ignition & advance being done by the ECU).
Their guts are very similar to the Isuzu 4ZE1 distributors - the pickup/sensor module is physically the same.
I also have a 1987 Nissan Exa-turbo distributor. It has a later optical sensor module that also fits straight into the G200W & 4ZE1 optical dizzies - same spade 4-pin outlet & same 3 mounting holes.

Their discs all have the outer 360 slots and inner 4 slots. However, the inner 4 slots may vary in radial length.
Of interest is that Exa disc has 1 of its 4 slots elongated, hence it has potential use in "dumb" sequential ignition or injection systems. (That's for those that don't have intelligent "sequential" ECUs, or do not want to elongate a slot themselves.)

I'm only starting to investigate the dizzy alternatives. There are aslo other vehicles with similar dizzies - all with 360 outer slots, and with the same pickup and module except for their plug position (and type?), and maybe mounting holes.
I'll have to find my notes, but "our" & Exa's module has a modern part number and appears to be available.

As to bolt-ins:
The Exa dizzy fits into the GxxxW heads, but would need an adaptor or conversion from its shorter & female offset slot to the geared drive of DOHCs (& 4ZE1).
The 4ZE1 dizzy has potential for shortening to fit G200Ws.

But there is lots to determine. Although the bodies' lower (inserted) diameters are the same, their mounting bracketry and orientation may be a problem, though orientation is probably more of a rotor & cap issue.

Electrically they will(?) all be the same. 5V or whatever supply. Square wave pulses for every slot. Longer pulse for the elongated reference slot. (I think all slot leading edges are at 90 degrees with trailing elongation. I just hope the ECU triggers at whatever the non-elongated edge is!)

For those with reluctor dizzies, although I'm working on a twin-fire dizzy for RB & Gemini dizzies (with Gemini-RB reluctor fitted), I saw today that one DOHC reluctor dizzy had a different construction so that although the method remains, the twin-pickups will need different spacing etc unless an RB "breaker plate" & reluctor cam/lobe can be used. Though maybe just the breaker plate (the big flat round "bearing" plate that the reluctor pickup & ignitor bolts to) is needed if the reluctor lobes can be reduced in diameter.
The system involves removing 2 opposing lobes. Each pickup then fires two cylinders (wasted spark: 1&4, and 2&3) and requires an ignitor for each, though I am also working on a multispark twin-fire CDI for the ultimate hedonist.

Geez that's a long FYI, but I can't get over excited - 2 New Topics in one year is enough for now. (Wait till I have something real to report.)

I own 2 g200ws from Piazza's and both are optical. I'm pretty sure all Piazza g200ws are.

A guy running a 4zc1-t in a Gemini over here in NZ has modified his 4ze1 dizzy by blocking up all of the "360" holes but leaving one open before the #1 (4 hole) slot, which gives a "reset" function for Megasquirt (so it knows what coil to fire) allowing him to run wasted spark.

I'm currently doing this with my g200w dizzy to run wasted spark on a g200w, I accidentally made my inlet manifold for the ITBs without realizing the dizzy cap fouls it! It's easier for me to just ditch the large dizzy cap and make a "CAS" style cap than to make a new manifold. Duh!

MANY thanks!
But check out the Nissan Exa turbo (1987) chopper - it is like PiazzaDOHC & 4ZE1 but has one of the four inner losts elongated - hence the sync/ref pulse.

I can (should?) post pics if interested.

So far it looks like all (or both!) DOHCs had opticals. I'd expect so - why have both?
But begs the question - why did GMH revert to mechanical in their later 4ZC1-t? [If interested, I can link an amusing post where someone - after a lot of crap and contradiction - ends up agreeing with my cynical suggestion that "GMH couldn't handle all-electronic"! (Mind you, he suggests I have some trouble accepting his reasoning. Alas there isn't any! )]

I'm not sure why GMH reverted to mechanical dizzy for the turbo, the Jap 4zc1-t engines are the same though. We only get Jap imported Piazzas in NZ but I though the Aus ones were pretty much the same?

I've got a Mitsi CAS in my shed which is similar to the one you describe except the slots get longer and longer (6cyl) with a whole bunch (360?) around the outside like the Isuzu ones. I guess the length of the slot vs how many it's read on the outside slots is how it knows what cylinder it's on?

Feel free to post pics/links.

The 4ZC1-t dizzies here (1986 Piazza) were mechanical with reluctor pickup.

The Piazza G200W dizzy I have is optical - same as 4ZE1 (Rodeo, Jackaroo) except for the body (length, shaft length & opposite cut gear for the 4ZE1's clockwise rotation). And the inner 4 slot lengths are lightly different, but each the same size - ie, no ref for No1 etc.
The inner 4 give the cylinder ref signal (like 6 for Mitsu V6).
The outer 360 just give a 2 degree crank increment - I guess easier than implementing CPU timing etc, and allowing for speed changes during a crank rev (but the inner 4 should be accurate enough for that if it's before but near the max BTDC advance.

Both 4ZE1 & Piazza G200W use the same pickup module (as does '87 Exa turbo) - namely TIS205 Crank Angle Sensor (replaces Hitachi RSB-03, RSB-06, RSB-07) TIS205 - though I still need to confirm all details. (Some 4ZE1s may use the TIS206.)
The Exa has one elongated inner slot so it's suited for sequential ignition/EFI on dumb systems.

Our Piazzas are also fully imported, although GMH specified changes to the suspension (which stuffed their handling), and it seems the mech dizzy (ie, why the heck would you go from a reprogrammable I-TEC to a fuel-only ECGI with mech dizzy!!!?).