Isuzu G-series Twin Cam

I don't understand the last - factory injector opening times are for the particular injector whether lo-Z with resistor or hi-Z vs voltage. And a lo-Z (with resistors of course!) still opens faster than a hi-Z. (Provided they are the same technologies - ie, a newer hi-Z may open faster than an old l...

The hi-Z has higher inductance; the lo-Z should hence open quicker. The resistors are only to drop the current to the hi-Z's normal required current and doesn't slow the current's rise time, but sure - overdrive it without resistors and it will open quicker. But hence why I prefer current limiters (...

Strange that the sense resistor exists. If the ECU can read that voltage value, then it should be possible to code. If not, it may be a combined hw & sw mod. And if still no to all that, then external circuity - which may be easier anyhow. I don't see that the ECU needs to know - especially if i...

Yamaha? Oh well, that's better than its alleged Italian design LOL! But the beauty of 8V is the low-down torque. What other engine can you double the vehicle's acceleration with a mere exhaust mod? Granted, I'm not sure how much the twin DCOEs and the "ICCA" replica-117 manifolds with tape...

That link refers to the 749 but I assume that that does do sample & hold from its reference to sense resistors that need to be upgraded (ie, to R05 2W). Is the 749 an 808 equivalent? All I remember is "not that number". I thought it was a 126 or 162 or ... ... ah... Maybe the 1227165? ...

I agree with what Tom said about little wear. But you like me have probably heard all the stuff about the GW's unreliability etc despite the GWs being VERY reliable (the G161W being the worst, and light-green early G180W being difficult for its piston rings). However, when you see what these people ...

Actually after writing above I was wondering if that Delco used injector drivers. Man - it's all so long ago. But then IMO it should be one driver per injector. But peak and hold shouldn't be too difficult even as an add-on - eg, after hitting ~16A drop back to ~4A (for batch fire!). For sequential ...

I was discussing the lo-Z issue with Poida recently. I did have a schematic showing that both loZ & hiZ could be used. I though that was for the 808 etc but can't be sure. Maybe one day I'll find the info again. I don't currently have the info in the 808's switching MOSFET. As I recall, it was c...

That price has hiked - the last I heard was $14 each a few years ago. At $40 each, that's $800 a set, and considering oversizes are not available, it probably makes a skim and line-bore competitive.

His uniqueness answer is correct.

Did you ask about the buckets?

It could be... But that's the later G200W and with the I-TEC (and yours isn't...). AFAIRecall, I generally see 12° BTDC and sometimes 10° BTDC, but that's typically the 117 G200W or Gemini EFI G180W which is pre-Piazza and doesn't have the I-TEC's locked optical dizzy. And the ITEC includes a knock ...

I'm glad you had success with the chain timing. Interesting that it ran being 2 teeth out. I wonder how it would be 1 tooth out - I recall some Gem G161Z racers saying the first thing they did was advance the cam one tooth (if I recall right). However I am certain my Isuzu Guru would have mentioned ...

The timing marks on Denny's pic relies on having bright links and thus isn't suitable for those with new non-OEM chains. PS - as per Dialing in your cams for a twincam ... http://img508.imageshack.us/img508/5570/g200wtiming3ec.jpg Though the pic is enough to get it mostly correct, it's reasonably po...

Thanks Poida, All seemed to go quiet on that front. I notice that full G200W gasket kits are being sold on eBay for ~$380 albeit via Sleeka (Adelaide) and not MDS, but it's the same kit, just relabeled. IMO it's worth getting that rather than using the inferior Permaseal VRS or head gaskets (thin be...

That's not a nick on the front exhaust cam is it? I forgot to say that yes, lift off the cams & remove the buckets. The proper (Isuzu) way to adjust the clearance is with the correct thickness bucket. But let's get real - shimming the clearance down is the practical way to go. And other engines ...

A bolt should be ok as a tensioner. Though I've heard it mentioned as being done on the early DOHCs, I've only seen it done on other engines. As to valve timing, chain-wise it's as per that link's marks - ie, crank-pulley mark aligned with idler/dummy-cam mark, and both can gear marks centered verti...

You need the complete front cover from a later GW.

Maybe try a new chain if it's stretched that much.
Unless the hydraulic seal/ring is worn an leaking more than it should.

The st'd cams are not adjustable.


below is a pic of the ratchet tensioners. The non-ratchet types are longer & round with a big hex nut at the end.

If I read the G200WE book right, they should be 0.13mm & 0.23mm. And knowing Isuzu, they'll be cold & static figures. Although an excess gap may not be too bad other than possible noise and heavier impacting , it's the under-gaps that can be damaging - eg, valve burn. If it's a newly built e...

I'd like to know why anyone would recommend a 20W/60 for 20W/50 applications. Maybe they get kickbacks from repairers? The original spec was SAE30W which is now 20W/50. I tend to use Castrol GTX, or GTX-2 if it's a new (but run-in) engine - ie, its detergent in an old engine makes a mess and causes ...

Nah, sorry - I don't know enough about carbs & Webers. But I suspect 44s to be the better choice. As you say, the GWs are big breathers. Besides, they can always be choked down. BTW - try to get the correct tune specs before getting the carbs. As my guru pointed out, back then F2s were $120 EACH...

I'm no expert, I merely built according to the directions I was given - namely that for street use for a st'd G200W, merely extend the 2:1 exhaust section (from the st'd manifold) to ~26-29" for ~400Nm torque at 3,000RPM. The dyno showed 300Nm @ 2,000 RPM and 383Nm @ 3,000RPM with torque reason...

AFAIK, all those 8mm valve seals are the same. (Isuzu, even Datsun/Nissan etc.)

Freshness is probably the most important feature... (Some use stale OEM seals!)

From memory, it's 44.5mm. But careful if using "normal" engine formula for the GWs, they just don't seem to work. The HDT tuning using twin Weber DCOEs should be fairly well known however - the key ingredient being the F2 emulsion tubes (or was it F12 - it's been a while!). For a stock G20...

Hmmm - I'd assume the one with the ECU, ie, N13.
But it might not matter.

Poida - HELP!

See How to strip a Delco setup out of a Pulsar/Astra . More FYI stuff at G180W injection / ECU issues (4th reply), and... HoldenGemini's Changing Engines (4th reply). You'd want the blue-top G180W inlet manifolds, or from the Piazza G200W. They are both the "up & over the top" types. A...