Isuzu G-series Twin Cam

Hey guys you can check out my new Bellett project over at: http://www.oldschool.co.nz/phpbb/viewto ... 17&t=14152

I've also got a Gemini coupe but its receiving some Toyota goodness instead

Plans for the Bellett is just a stock bottom end g200w with a bit of a cleanup on the ports, light flywheel and quad throttles tuned on a megasquirt ecu. Oh and a paint job and stuff!

Hmm, I got:

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Might just be a temporary thing though.

That engine sounds nice, make sure you post how it goes, I'm probably never going to get to drive my twincam NA... Oh, and I'm going to be running MSII so I'll be interested to know how that goes and see how you installed it etc.

Eli

Good one KE20!
You'll need the 117 type oil filter that faces upwards, not the Gemini forward-down type as originally shown. I'm after spares of them too, but swapping shouldn't be too hard. Many G200Ws in Oz are from 117s and Gemini owners want the rarer Piazza/Gemini types.

You already have the Piazza/Gemini sump which is what you want. The 117 has the "Florian" sump which doesn't fit.

And you have overcome the need for the "over the top" ECGI type inlet manifold (albeit "long"). 117s have the outwards rightside type which are too big for Belletts (but have 5 injectors).

Assuming a Piazza 5 speed gearbox, the rest should be straight forward. Unlike Geminis and Oz Piazzas, DOHCs and Belletts have the starter on the right side - which is the left side (where right means correct. Ha Ha!)
The prop-shaft splines may be different (fine spline &/or larger), but all types are available with Bellett type universal joints (those 1" Cortina etc types). The prop shaft should be the right length (later Bellett 4 speed = Gemini/Piazza 4 & 5 speed lengths).

You should have a "pusher" clutch fork as used in Bellett mechanical clutches and Piazza hydraulics. Otherwise conversion is easy with the right fork (but avoid cables - they break too often with "normal" heavy duty clutches).

You may have to turn down or swap the front harmonic balancer - 3 grooves may be too long.

And for front engine mounts, you can use the Bellett's RH mount (omitting one misaligned bolt).
The left mounts are obtainable - typically from later G180 SOHCs which are from Belletts & Florians. But consider the alternator mounting whilst you are at it - I prefer later 10mm bolt alternators and recommend either Nissan 55A N12 or 70A N13 types with internal regulators (see posts elsewhere like RodeoBobs alternator upgrades - possibly on OzGem. The original regulator is replaced with a jumper plug to get ign-power and charge light to the altenator).
The N12 has the same mount spacing as Geminis and most DOHC mounts, but I fitted the wider spaced (and bigger 70A) N13 to my 1965 Wasp (Bellett ute) which has a G161 OHV Florian engine and Rodeo 5spd box (with st'd Wasp hydraulic clutch and recently fitted Jackeroo 4ZE1 RHS reduction starter on the LHS of engine/box).

The simplest engine mount may be bent sheet metal (6mm thick?), but I'm unsure if this fouls the alt bracket. (Design it for 45 degrees - some mounts are 30 degrees but I think all standardised later to 45 degrees (eg Florian from 30 to 45).

I think the Piazza gearbox shift extension fits reasonably well into GT Belletts, but sedans have no extension (they suit "standard" gemini boxes). Some Bellett owners modify the tunnel to imitate the GT, though I suggest make it to suit your "common" extended gearbox (Piazza, Rodeo? etc) and make sure no floorpan strength is lost. (FYI - the Wasp tunnel is removable so its early 4-speed box can be removed easily through the cabin. I'd like to imitate this in Belletts for easier gearbox access and removal (even if not pulled out through the cabin).

I prefer your later "long rectangular taillight" Bellett which are rare here on the North Island (though I have a chopped up later one with the "GT-R style" shorter bonnet and rare quarter vents which comprised the last Bellett shipment to Tasmania - aka the South Island). I like the various improvements like separate left/right parkers, hazard lights and indicator stalk beam control, though I'm not sure if their lighter upper control arms (being s-, not u-section) would handle my rough treatment.
Also the front turret upper-rear indentations make it possible to fit longer brake masters. (Mazda RX4 will fit, but get a sleeved one. Also heard some Mazda or Ford Laser, late 1980s?. And front discs - Magna '85-'92 4 stud vented discs replace the drum, and fabricate brackets to fit their calipers. Brake booster - could use the GT-R method with dual circuit master and a remote booster on the LHS (identical to some early Mazda...)

I have standardised my GTs to the same long rectangular taillight model but this is mainly for taillight, headlight, grill and dash interrchangeability. Alas they still have the old electrics with floor dipswitch etc.

It looks like you have GTR type rims (which are the same as early Magnas or something similar).
And you found the troublesome front turret rust (lack of drainage holes).

Have I forgotten anything? Only the exhaust if you want >360Nm torgue from 2,000 RPM - standard G200W manifold; about 26" 2:1 section, then 2" (or more).

Apparently the 180HP Piazza turbo in the Bellett had a bigger power to weight ratio than the old Brock Commodores (from the mid 1980s?).

Oh - get some front neutral to negative camber. And I recommend 2 standard transverse leafs up the back mounted "back to back" (simple but effective).

Good luck!
Peter.

What are your quad throttles off? If i can find a set cheap enough...

You might find the SOHC crank pulley fits if the piazza one gives you clearance issues. Ditto remote oil filter mount kit off EBAY if you cant get a 117 item.

Sweet cheers for all that info IZU! Especially the brakes all they're my main worry. I see Brett from ozgem used mitsi brakes front and rear from a Sigma - We didn't get magna's here so I guess its just a re-badge?

I never though of using a Gemini front pulley, I'm pretty sure the g150 pulley doesn't fit properly. I've got a g200z in the shed from my Gemini so I'll try that out. I think the engine should mount properly with the standard mounts and g150 timing plate. I'll soon find out!

Bits like the 117 filter housing and 1800 Bellett items are pretty much impossible to find over here so I may have to make something up or buy from Aus, here was my original idea for the oil filter housing.



I was intending to use the original Bellett gearbox if it works. Using a Gemini pressure plate, Bellett clutch (bit small though, but is the only one that fits the spline) and the lightened flywheel I got. Unfortunately the Piazza gearbox was completely stuffed. You ever had problems with a stock Bellett box?

As for the inlet manifold I'm starting from scratch, I have just updated the thread last night - Cheers for the info on the exhaust, I'm not 100% sure the factory manifold will fit though?

I also prefer the later tail lights, I don't think we got any variation in NZ, they've all been the same spec from what I've seen (i.e all 4 door 1500's) - I went to look at an Isuzu Wasp at a junk yard but it was well and truly rusted away - Would have made for a very cool project as its the only one I've ever seen.


Archangel, the site was down for a few days but its all go now

Gemcoupe, The throttles are off a Toyota silvertop 4age engine, they're cheap as chips to get here. (usually under $200 but can find them really cheap) A remote filter off the original housing probably won't work either



Thanks for the info and comments guys. Feel free to add to anything I may have wrong from above.

No probs, that's what good forums are for!

If Brett is "BellettRacer", then he may have referred the older conversion with earlier Sigma hubs & discs which are not vented, and require machining else rare bearings.
The later conversion is much easier (just remove the drum and fit the disk) & it's vented.
The info I have is DBA 221 disks from Magna/Diamante TM, TN, TP 1985-91. (I have found them on 1992 ID plated Magnas.)
Apparently also on the Galant HG 1989-90.
Just ensure that it's 4 stud with the same spacing as Bellets (not Geminis etc). Maybe download a DBA disk brake catalog or similar for reference. I can't remember if the 13" rims fit, but I'd recommend 14" rims anyhow.

I think the Gemini front pulleys fit, but not the old G-OHVs.
And the problem with the front mounts isn't the front plate (I'd suggest keep the original G200W plate), but that the holes on the side of the block are further back. (I might be getting confused. I fitted a G180 SOHC to a Bellett GT after cutting&shutting its sump, and converting its 30 degree LH mount to 45. Later I fitted a G200W to Florian and effectively reversed the process - converted 45 degree LH mount to 30 degree (ie, back to its original G180 SOHC config), and fitted the non-Bellett/Gemini sump. (I now have a 1975 Florian crossmember with "standard" 45 degree mounts.) And now I'm not sure what the RH mount is off - the Bellett RH won't reach the block holes will they? Or is it only the LHS where this is an issue? That's the problem when you have a mix of GT-R and SOHC bits!)

See if you can get the 117 oil filter from somewhere. They are pretty light, but otherwise a remote job will do.
If there are G180 non-Gemini SOHCs (with heads that look like Nissan/Datsuns with a side cover to adjust tappets) they too may have the right filter assembly - but not the G161 equivalents.

Bellett gearboxes will fit, but you will definitely want a 5 speed.
Keep the Piazza DOHC bell housing and transfer it to a Gemini 5-speed (change the layshaft's needle roller to ball bearing if required).
Also keep the Piazza box's front cover plate & thrust bearing block, throwout lever, mushroom bolt/pivot. The steel centre carrier plate may also be sought by various people.
FYI - my G200W developed over 360Nm at 2,000 RPM; when racing I'd just get off the line and then straight into 5th gear. Geez - I even want a 6-speed in my G161-OHV Wasp (it currently has a 0.855 5th & st'd 4.55:1 diff).

I used a heavy duty Rodeo clutch in my G200W because its standard clutch slipped (no wonder, I had twice st'd torque!).
I suggest using the correct clutch plate and convert its centre to suit, but again I'd recommend a 5-speed box. (I've done the opposite - fine spline centre in Bellett clutch plates for 5-speed boxes behind the G-OHVs.)

And there are at least 2 versions of rear taillights (excluding the GT) with the difference being the size of the holes & sockets for the smaller parking bulbs (used for left, right or both). I think too there are versions without these parkers. (Collect both sub-harness types to cover yourself, ie, 6-pin spade to light sockets.) The rest (lenses etc) should be the same.

And you maybe right about the exhaust manifold - they fit Florians and Wasps but you may need extractors for the Bellett for the tighter fit. (Maybe a reduction starter might fit and be shorter than normal starters??)

Cheers.

Had a feeling they were 20V throttles, mind posting a picture of the back [where it mounts to manifold] and what size the butterflys are? I SHOULDNT be doing it to mine....but man its too tempting.

Im with Peter, use the Gemini 5spd on the Piazza bellhousing, that way you can use a good clutch. All G DOHC's ran the larger flywheel [same as G200z], so get yourself an off the shelf Heavy Duty item for a G200z. From memory, my Exedy HD for my old 161 was around 180rrp AUD.

Also, any idea on the difference between blacktop and silvertop ITB? Theres a set of blacktops for sale in bris but at 430 they are abit steep, would be cheaper for me to get them from kiwi land and ship em over.

I'm loving this forum! - Great info.

I definitely want to switch to a 5 speed but Isuzu bits are a bit harder to get here. I may have to get it going with the stock box untill I find a 5 speed. Does the Gemini box bolt into the crossmember or will this need to be modified?

Cheers for the info on those brakes too, that saves me a huge effort! - I won't be running the stock rims as I don't have a full set so thats no big issue

I'm actually not sure on the mounting holes, I though they were in a similar spot but I didn't look very hard. I'll have to have a decent look this weekend.

GeminiCoupe, the silvertop ITBs taper from 45mm (at the trumpet mounting face) down to 42mm at the butterfly. Blacktop's are 45mm at the butterfly, blacktop ITBs are usually twice the price too and are harder to come by. You have it all wrong, you should be doing it to yours

I was told Kiwis couldn't give away their 5-speed Piazza boxes! (Was it Wedgenut that said that? I could check...) Get a Piazza DOHC box!!

The Gem & Piazza boxes should bolt straight in, BUT....
- you may need the speedo-cable L-piece if the rear crossmember interferes;
- move the rear mount on the box;
- you may lack clearance at the top of the transmission tunnel at the rear of the box (ie - lower the crossmember, or bash tunnel, or fix during "extension shifter" modfication).

Later gearboxes (may) have two sets of rear mount holes at slightly different heights.
Either set MAY line up with the crossmember holes (using a standard Bellett rear mount)...
But if the crossmember holes are between the gearbox hole sets, then use the rear mount & bracket that often comes with 117 boxes (maybe Piazza & others?) This is a T-bracket that uses all 4 gearbox mount holes and has the removable rubber mount bolted horizontally to the bracket between the 4 gearbox holes which should line up with the Bellett gearbox crossmember. (Clear as mud?)

Note that the bottom (rubber) section attached to the gearbox rear T-bracket can come in different interchangeable forms.
One is the normal Bellett/Florian mount (2 vertical thick bolts).
Another is the U-bottom which sits inside a U-crossmember and attaches with 4 smaller horizontal bolts.

A key point to note is that if assemblies are not directly interchangeable, there are usually standard Isuzu parts that allow adaptation of from one Isuzu to another.
Direct fits include (eg) 1985 Jackeroo/Rodeo LSD into 1965 Wasp (just change the banjo).
Adaptations include DOHCs or Piazza 4ZC1 turbos into Belletts which require (eg) changing oil filter assemblies and mounts, or Gemini gearboxes behind DOHC with a bellhousing swap (& maybe layshaft front bearing; throwout levers etc).
Even later 4 & 5 speed boxes can be placed behind the early G150 & G160 3 bearing engines (with later flywheel & starter, engine breather, etc).
Even the highly prized GT Bellett "gauge cluster" is easy to imitate, or improve using the later Jackeroo cluster etc (ammeter excepted - but these are stupid anyhow!).

What I'm saying is that after a while, you should find that there is little need to manufacture anything for the type of conversion/upgrade you are doing to the Bellett.
Trouble is (1) finding out what the part is, & (2) getting it!
The only real pain with the Bellett is the differential - like the local Gemini, it is not compatible with the Wasp, Jackeroo, Rodeo etc. Hence a Bellett LSD can be difficult (unless you find few local GT-Rs and their spares, LOL!!).
Apart from engine mount-bracket manufacture (mainly because the correct ones are hard to get), alternator mount changes (due to modernisation) and clutch-plate mods (fine/course etc), I don't think I've seen an "Isuzu adaptation" that requires "complex" fabrication or modification of a oil filter blocks, flywheel, crankshafts, etc.

I'll have a good look at the Piazza box I have tomorrow and see if it will fit up properly, unfortunately its got a few teeth missing so I'll have to find another one.

What advantage will having 2 leaves back to back in the rear give? and what have you done to adjust camber in the front?

Cheers heaps for all the info!

Two leafs is just a simple trick for better handling (usually). Probably more common on GTs. Should help rear end NOT tuck under.
Some swear by a rigid rear leaf but (1) this'll eventually break the mounts to the swingarm & (2) this is aka a live axle (non-independent).
Sometimes rear springs in the front can be good - they are a bit stiffer but might lower the front by about 2-5cm. Rear springs are also easy to remove from both the rear and the front. The fronts are much longer and really "spring out"!

Neg camber at front is often by extending the lower ball joints.
Can also move upper arm pivot bolt inwards (weld & re-drill).

I chopped 1/2 inch out of my upper wishbones (but they were the earlier types with U-cross section, not the late S-section) and had them oxy-welded together by a "true engineer" in the late 1970's.

Usually the Belletts only adjust down to about +0.5 degree camber (with no shims) and tend to understeer under power.
I found -2deg pretty good for dirt rallying, but later neutral (0deg) was a fairly good compromise for road handling and tyre wear.
A mate runs about -6deg front and rear!

Updated

Woow! Two days ago i had found the Mobile Phone TV... o-oo I'm so glad that I decided to advise you too l:)

I consider myself a bit of a road warrior. I am on and off jets and through airports at least twice,
usually 4 times a week. I can catch up on news, watch a Discovery program, check up on the stock market or just find something interesting.
The live guide works like cable at home and the connection speed is very good. All in ALL - I RATE A 5 Star program!

here is this miracle http://bit.ly/awesome_mobileTV
sincerely, your Alexis....

Great! Another site www.mobiletvelite.com added for spam (info@, admin, :110 etc) and blacklists.

I love these spamsters that make motoring safer by killing mobile devices.


Don't fuckwits like that realise what these sites are about? As if we need EXTRA entertainment.


Thank you Alexissss - a true combination of science and religion (Darwinianism & [survival of the fittest | an ire for an eye] ).