Isuzu G-series Twin Cam

I hope I am not going across old ground but my search came up short.

I am looking to set up a distributor on a G200W with either points and condenser(yes I am old school but I can fix this stuff) or a simple electronic ignition arrangement. I am setting the engine up with twin carbs and would like the ability to modify the advance curve.

I have a late model G200W distributor out of a 117 coupe that I would happily swap if it is of any value to others.

Keen for any comment,leads or advice

Thanks

The best is the RG dizzy. RG is our name for (FWD; early model) RB Gemini dizzy guts into a Gemini (T series) RWD dizzy and it's the standard dizzy solution for all G-series Isuzu engines. (Not sure what construction threads exist here, but OzGemini had a few.)

For the GW, cut the shaft 10mm below its retaining collar. Remove the collar and fit the GW drive gear with a 4mm pin and some shim (0.07mm?) to fill the 12.0mm vs 12.4mm shaft differences.

The RB/RG uses a reluctor system (the most reliable and accurate) with internal ignitor.
Normally the RB's sub-harness with ignition coil is used, but if you're not using the internal ignitor you'd extend the reluctor coil wires to whatever electronics (EMS/ECU; ignitor or timing).


To mod the curve I'd suggest locking the dizzy shaft (washer; else glue) and using the Jaycar programmable ignition kit. (I still haven't build mine.)

Thanks for that. I will pick up the dizzy on the weekend and have a good look at it.

You can of course use a cut-down Gemini dizzy and retain the points, but if you do the reluctor conversion itself then you'll know how to fix it. I keep a spare breaker plate with reluctor pickup and spare ignitor in my car.
They are very reliable (despite what people seem to think) and the only failure I had (after at least 5 years of use, and my dizzies are near the rear of the engine - hotter than the front mounted twincams & Geminis) turned out to be an internal wire link that blew; the electronics were still fine.

How good are they? You'll probably read elsewhere how I abandoned my sub-$100 sequential CDI - especially after my cold G161-OHV started one morning with a 5.2V battery. (FYI - I was merely seeing how long my reduction starter would continue cranking on my stuffed battery since I knew the car wouldn't start (no 12V system ignites at 5.2V - I'm not stupid!) and I knew I'd have to swap the battery...)

What other advantages? Never having to alter the timing as points blocks or cams wear. Never having to replace nor maintain points or condensors. Much higher cranking spark energy. The ability to use any IgCoil - even Bosch MEC-717s (or whatever they are) with ~0.4 Ohm primaries - ie, ~ 3x to 4x the primary current of a typical RB or RWD Gemini IgCoil.
Note that the RB ignitor is current limiting, hence any IgCoil can be used, but the common ND "blue" coil is one of the best & beaten only by E-type coils.


BTW - when I said "I still haven't build mine" I meant I still haven't built my own PICAXE 08M2 version of the Jaycar programmable ignition.


Also - keep the 117 dizzy. You can probably sell its ignitor to some sucker; maybe even the whole dizzy. (Trust me - they are antiquated and vastly inferior (similar technology to Camiras etc), and no good above 7500 RPM.)
But you'll need its driving gear for the 'Gemini' dizzy conversion.

good points.no pun intended.

I guess my interest in staying with the points and condensor distributor was aimed at being able to change springs and weight to modify advance curves as the engine needed but that is a little way off for me.

The car already has a GZ engine in it with a Electronic distrubtor of some type that from memory looked exactly the same as the points one and had the same rotor and cap. Worked well at high revs on a high compression engine but the dyno guy said the advance curve wasn't able to be modified.

Might be a good starting point for me as it is already wired into the car and I am starting with a stock G200W?

I will heed your advice and hang onto the dissy's I have for the moment. I will get a photo of the GZ distributor I have and post it up.

I've seen a lot of people spend $100's getting their dizzies recurved and I think for what? It's still only a 3-step curve for the RPM and up to 4 steps for the vacuum (double diaphragm) with no "exception dips", and it wears out, and and then if you want to change the timing again...
So why not the Jaycar for $70 which is 2-curve 11-step programmable etc. To that add the ignitor and vacuum transducer (if desired), plus the hand held programmer (~$70) unless you can borrow or share.
The ignitor & vacuum should be cheap from Pinch A Part or other wreckers.
Of course if you are prepared to wait a millennium or three I might finally build my equivalent which I expect to cost $10 in parts (based on a $3 PICAXE 08M2) plus a $5-$10 matchbox sized case. Programing would be via (USB to) serial interface from a PC etc.

There's also the possibility of using certain EFI EMSs for ignition only.

But hence the beauty of the RG dizzy - standard Gemini hardware with RB Gemini guts (the breaker plate & pickup/sensor and ignitor are shared by other Jap cars) which can be used for any EFI/EMS system.


But the RG can also be modified just as the st'd Gemini since it uses the original Gemini's springs, weights & vacuum advance. (Only the "cam" and breaker plate with sensor is changed.)

You might have the RG dizzy you have if it uses st'd Gemini rotor & dizzy cap, else it's an OEM electronic dizzy.

The G-W points dizzy if OEM will use the same rotor and cap at Belletts & Florians etc - ie, typically use Datsum 1600 etc parts (cap & rotor are close enough). They are also half the price of the Gemini equivalents (that's my only migration negative going from original OHV points dizzies to the newer RG).


FYI - my 383 Nm G200W was stock. I think it had around 160-170 psi compression.
It handled the torque ok, though not the clutch (obviously) nor the gearbox. (Gemini 5-speed with DOHC bell; the output shaft would twist.)
Reliability is the same as standard.
So too is the (cam grind) 230HP version provided the pistons are upgraded, though some claim they were ok (not that I recall who or what forum, and I think it was OzFemini which had so much bullsh on it!).


As I recall, the GW dizzy gear had 13 teeth and I was starting to check to similar gears (the 4Z dizzies rotate in the opposite direction).
Though if dizzies were ever a problem, I intended distributorless ignition using the flywheel ring-gear for timing.