[Bammo]

With thanks to the many others who have gone before us in doing this!

So this is my Holden Drover. It's a 1985 G13A engine model in pretty original condition motor-wise. Did a clean up of the motor, new cooling system and in the process tried to adjust the Aisin carby to get rid of the stench of unburnt fuel and random idle speed changes. No luck there - and what a pig of a carburetor to work on. The eBay rebuild kits are cheap but I doubted that would solve the problems and a full commercial rebuild was going to be horridly expensive.



So after some reading I decided to just bolt on the Corolla 4K Carby. The carby came from eBay - was about $150 delivered.

http://www.ebay.com.au/itm/Carburetor-f ... 9#payCntId


The process is pretty simple. At a high level you need to remove the old carby, replace the gaskets, install new studs in place of the bolts, modify the adapter plate, fabricate a new throttle mount and restart the car. Easy! Make sure whenever you are working with fuel you have a fire extinguisher nearby.

Step 1 Disassembly.
Remove the earth connection to the battery.
Remove the aircleaner lid and remove the filter and top of aircleaner assembly. Remove top bolt of aircleaner on the carby.
Disconnect the fuel line from the barb and plug the end of the fuel line temporarily.
Disconnect the electrical plug
Disconnect all the vacuum lines going to the carby as well as the 2 water hoses. The only one we are going to be using is the vacuum line from the distributor cap so don't worry about damaging any of the others in this process.
I shortened all the unused vacuum lines (I think there are 3 excess ones?) and plugged them with a BB pellet. I used a hoseclamp and old bolt to plug the hot water lines.
Carefully disconnect the throttle and choke cables and lay these aside.
Unbolt the old carby and lift off. Remove the adapter plate under this.
Either tape off or stuff an old rag into the hole in the manifold to stop crap falling in.



Step 2 Carby Prep

Using a blade from a Stanley knife carefully pry off the old gaskets - there are two one above and one under the adapter plate.
Clean off the mounting plate on the manifold with a bit of throttle body cleaner or whatever you prefer.
Carefully empty out the fuel from the old carby
Remove the fuel spigot from the old carby (its a Banjo Bolt arrangement) - needs a bit of force to shift it but be careful - we need this bit.
Remove the threaded adapter from your new carby and discard as we will reuse the Banjo Bolt here. Note that this is tough to remove - think they use Locktite on it. Go slowly. I found putting the threaded part in a vice and turning the whole carby was the safest way of doing this without damaging anything - a simple spanner on the thread started stripping it.
Bolt the fuel spigot into the new carby




Step 3 - Modify the Adapter Plate
Fill in the semi circular groove on the adapter plate with some JB Weld or similar automotive repair goo and once dry use fine sandpaper to flatten it down. If you scrape off the excess JB Weld with the Stanley blade before it dries this is easier. Put the wet & dry sandpaper on a flat surface and rub the plate over it - this helps ensure you don't round off the plate.
Cut with a Dremel or a hand file a small groove in the adapter plate. I'm unclear on whether you really need to do this as some You Tube videos reckon you can just ignore this.
The smaller of the 2 holes in the adapter plate can be chamfered slightly to provide a smooth transition into the larger hole in the new carby - how much difference this makes is questionable but only takes a few minutes so may as well.
Use either the old gasket or the adapter plate as a template to cut out new templates. I used SCA 0.8mm gasket like this:
http://www.supercheapauto.com.au/Produc ... 000mm/8513
Note the old gasket has extra holes you don't need.



Step 4 Studs
The bolts from the original carby are no good - you need studs. I had some spare 50mm bolts in the correct thread pitch in my box so just cut the heads off them and with a file made a slot in the head so they were easy to turn with a screwdriver. Clean up the threads (test that the nuts fit easily now - DON'T wait until the whole thing is assembled...trust me ). I made one of the studs slightly shorter as there is less clearance on the front left bolt on the new carby (screwdriver pointing to the short one). Clean out the holes and using red Locktite install all 4 studs and allow to set.



Throttle Mount
Using a bit of scrap 2mm steel or similar and a hammer and vice fabricate a new mount for the throttle cable. I made mine out of a leftover bit of trailer panel with about a 20mm wide base and a 40mm wide top but really its a suck it and see exercise. Drill an 8mm hole in this with a slot to allow the throttle cable to be installed. At the base drill another 8mm hole and I used the existing bolt on the side of the manifold that use the hold the bracket for the hot water line that went to the carby. That hot water line is no longer needed so worked a treat for this purpose.

Now this is not the most stable and rigid bracket in the world but for my application (low speed gun buggy) and the 12 minutes it took to bash into shape I am happy. The little bit of flex I get is actually good for my application - for a road car you might want to make this a bit stiffer. With the carby sitting on the studs check the angle of the throttle cable coming into the new cam on the carby. You can see from the photos that I tried two different positions to get this right.

The end of your throttle cable has an 8mm doohicky on it. The corresponding hole in the new carby throttle linkage needs to be opened up carefully to accept this. DON'T use a drill for this - the drill bit will catch and either fling the carby or worse damage the linkage. Just be patient with a round file and open up the hole.

You may need to add an additional spring (or put some graphite on the throttle cable) if there is any hint of stickiness in the throttle returning to zero.



Fitting the Carby
Carefully remove your rag/tape from the manifold
Check the orientation of the gaskets and adapter plate are correct and install
Place the carby over the studs oriented so the throttle linkages are facing the driver and the fuel spigot is at the front.
Place washers and spring washers over the 4 studs and then install nuts and tighten. Don't over-tighten these - snug fit is all that is required.
Connect the throttle cable and adjust to ensure the angle is correct (full throttle on the pedal opens it right up, no throttle closes it right down). Make sure the cable doesn't lift off the cam when you do this, you can adjust by slightly bending the bracket, adjusting the height of the bracket and the length of the cable. Sounds complex but when you look at it its pretty obvious.
Install the choke cable
Install the vacuum line from the distributor (I used a new bit of vacuum line for this)
Install the fuel line.
Connect the electrical plug
Install the aircleaner. For my setup, I had a spare bolt that fitted the thread in the carby no problems and was the right length with a small washer at the top. The aircleaner has sufficient clearance that no additional changes were required but I note that some You Tuber say you need to modify this slightly to provide clearance. YMMV.


It took less than 15 seconds of cranking and mine fired up with no fuss or muss. Idle and mixture were pretty close to spot on straight out of the box!

Drive testing yet to be done (and I will update when so)

Hope this is useful to someone else thinking the same thing. The key take aways from this experience for me were:

1) Don't bother trying to fix/improve/tune the stock carby, its a PoS and you are wasting your time
2) This is a lot easier to do than I thought - not at all a hard task for someone with a few basic hand tools.

Total time was about 5 hours but that included a lot of sitting staring at the thing with a beer in my hand trying to figure out what to do!

[pete_79]

Nice work.
How/where did you mount the choke in the cab?

I can see this mod happening in my near future. Done about as much messing around with the stock carb as I want to do and it's still a pig to cold start.

[barbender]

Very well done Bammo, next job for me now, hey, what is the paint colour/supplier/name of etc of your rig !

[sideways]

pete_79 wrote:

I can see this mod happening in my near future. Done about as much messing around with the stock carb as I want to do and it's still a pig to cold start.

Told you.

Great write up, when I did it I had trouble finding information.

FWIW for the stud in the top of the carby that the air hat bolts to I used the original stud out of the 1.3L carb upside down.

[Bammo]

That colour is official Army issue olive drab sprayed over the faded blue with a bit of a lackadaisical approach!

Pete - my Drover already had a manual choke installed so no mods required - the end of the choke cable fitting straight onto the Toyota carby. If you don't already have a choke cable then unless you live in a really cold area I would just ignore the choke altogether.

[Bammo]

So made one slight modification today. Installed a spring from the side of the of the aircleaner to the return spring on the throttle (front side of the carby) _ I think the age and poor condition of my throttle cable was making it a bit sticky and the second spring helps ensure it closes nice and crisply. Spring was $3 from Bunnings.

Tweaked the idle speed slightly, checked the timing and took her for a drive. Noticeably smoother power, no flat spots anymore. No smell of unburnt fuel, clean exhaust and after 15 minutes the idle remains rock steady.

Job done - thanks Corolla Carby!

[barbender]

Any body know what the groove is for that Bammo filed into the base plate?

[fordem]

Did he file it or fill it? If I remember correctly the 8V G13 engines have a brass "swirl" jet in the intake throats, I think they feed through that groove.

Attachment:

swirl.jpg

[barbender]

The pic shows a filed grove in the adapter plate, at a guess about a 15 degree angle or thereabouts.

[fordem]

One of the pictures shows the base of the inverted carb - there are two holes - sort of "in between" the two barrels, it looks like that groove might link one of them to the one of the barrels, possibly the primary - I'm not familiar with the Corolla carb so I can't say why it was necessary.

I got curious and started searching online - apparently there are screws in those holes (to hold the base of the carb to the body) and one of them has a vacuum passage through it - Ack's FAQ shows the slot and describes it as a "vacuum passage", but I have not yet discovered where the vacuum goes.

Further digging around suggests the vacuum port may be a part of the power valve mechanism - a means of richening the mixture for power when the manifold vacuum is low, as would occur when the throttle is open.

[barbender]

Thanks fordem, makes sense now, regards

[Bammo]

Looking at the available evidence suggests it really isn't needed for the 4K carby but since I already had the Dremel tool setup I figured it couldn't hurt. The couple of drives I've taken it on suggest that its working perfectly as-is so in the spirit of "if it aint broke don't fix it" I would just do the same as I did!

The engine starts cold instantly now, the choke works as it is supposed to and idle speed stays rock steady from cold through to hot. Cannot be happier with this and so pleased I didn't waste any more time on that stupid Aisin carby!

For those who are interested in the paint colour - it is the standard Australian army camouflage green. Its available commercially as Protec 343-1166 from http://www.protec.com.au/. The only difference from this commercial paint is that it doesn't have the near infra red absorption properties of the genuine army stuff so it is a bit more visible at night to NVG equipped people!

Also see viewtopic.php?f=37&t=51221

[barbender]

Great outcome Bammo, thanks for the paint info, good work - regards

[barbender]

Bammo, now that you have had the carby fitted for awhile how is it running, have you had the Suzi off road at all, if so how did it go on inclines and declines, regards.

[Blkfxx]

Fitted a "3/4K" corolla carb to my brothers sierra, had to swap the secondary jet with the secondary jet out of the Aisin. Ran like total shit at mid/full throttle otherwise.

Only issue is the model we got didn't have the fuel cutoff solenoid. Put the one from the Aisin in and it idled great, but it's just too long and tore the o-ring on re-install (fiddled with wire as it was damaged) and now idles crap.

Does any know where I'd find the right solenoid for the 3/4K corolla carb?

[Bammo]

barbender wrote:

Bammo, now that you have had the carby fitted for awhile how is it running, have you had the Suzi off road at all, if so how did it go on inclines and declines, regards.

So remember that this is an off-road vehicle only. We gave it a good workout last weekend - travelled maybe 80kms over the farm over a 7 or 8 hour period over 2 nights. - mostly on paddocks and tracks. Never had it above 50km/hr so cannot report on high end performance as that's not our thing. It ran flawlessly - started every single time first pop and never looked like stalling or missing a beat. Power seemed about on par with before or slightly better- the Drover motor was pretty tired to start with and still is so it aint no ferrari but it gets up to speed no problem. It climbed the embankments and what have you with aplomb.

The 2 most noticeable things about the carby were these: 1) the fuel economy was outstanding compared to before. I think we used something like 13 or 14 litres of fuel which is staggering given how many hours we were puttering around the farm. 2) The really nice thing was the engine temperature - the Drover was very quick to overheat before (even with the new radiator) but now it stayed rock steady all night.

One of the single best mods I have done to the car so far...

[barbender]

Bammo. thanks for the feedback, awesome outcome, regards........

[DaveA]

Hi,

I've just purchased a '90 1.3 SWB Soft-top which I collected yesterday and which already has the Corolla carby fitted.

Driving it home last night and to and from work today, I found it wouldn't rev much over 3,000rpm. It feels to me that it might be running massively rich and the idle is high at around 1,500rpm.

Apparently the previous owner recently fitted a K&N filter, which I would have thought would make it run leaner, if anything? Maybe it's actually running too lean!

Does anybody know the starting point for the jets, e.g. "screw fully home then out 1.5 turns" or similar? Is the mixture actually adjustable or do you have to experiment with different sized jets?

I also noticed that it has WAY too much oil in the sump..... about 10mm over the "high" mark! I'll drain and refill on Saturday.

TIA,
Dave
Darwin, NT

[sideways]

The only mixture adjustment is idle circuit mixture.

For the high idle it could be

Vacuum leaks!!!
Idle screw turned in to far
Throttle cable to tight
Shafts sticking


For not revving over 3000

Blocked jets
Blocked fuel filter
Dead fuel pump
Ignition breakdown

[DaveA]

Awesome help - thanks for that info.

Any idea how I locate the jets so I can check them? Would I need to locate a manual for that carby?

Cheers!
Dave

[DaveA]

I just had a quick squiz at my carby, and it looks like it might be back to front.

The fuel inlet is at the rear and the throttle linkages are at the front which means the throttle cable has to snake over the top of the engine and back in from the left side of the engine. The cable is also "floating" in space with no bracket holding the "sheath"

So, just to confirm: looking from the front of the vehicle towards the rear, the fuel inlet banjo should be at the front and the throttle linkages at the back, yes?

[DaveA]

Bump

[bumstein]

I’d say it sounds backwards, perhaps post a pic and we could give you an idea then eh?

[Bammo]

Dave - I reckon the bloke who installed that carby read just enough on the internet to be dangerous and when he couldn't make it work properly he flogged it to you. A few people on youtube talk about mounting them back to front which does have some advantages but only if you are prepared to fabricate the correct mounts for the throttle cable.

Your throttle cable not being correctly supported might be what is causing the limited range of acceleration - can you manually adjust the RPM at the carby itself by rotating the arm? Does it go above 3000rpm if you do this? If so then you know the problem is that cable not being properly supported. The bracket I made is pretty agricultural and took a bit of fiddling to get right but is the difference between it working and being a failure.

Personally I would rotate the carby and mount it correctly - works well for me and a simpler setup.

[DaveA]

Hi Bammo,

Yes, I rotated the carby on Saturday and am awaiting a new accelerator cable.

I hooked up the fuel, etc (with new fuel line & vacuum hoses) and it started fine. I don't like revving an engine too much when it's not under load, but it seemed to be happy to rev pretty hard.

So, once the new cable arrives I'll also be fabricating a mount. Your article was very helpful, so hopefully I won't have too many issues.

I did notice a slight weep from the banjo, so I might need to replace that too. I take it that these should be pretty easy to source?

Thanks to you and all the others who've responded for your kind assistance! Fingers crossed it should be up and running this weekend.

[DaveA]

Having a look tonight at where the newly fabricated bracket for the accelerator cable is going to go, I notice there's only one bolt on the manifold that I can attach it to.

Did you just mount your bracket using this single bolt? I'm just a little concerned that this might not be a stable enough mounting by itself.

[sideways]

The one I did was made out of angle iron and bolted to the bolts that hold the carby to the manifold. Same as how the weber kits do it.

[Bammo]

Hi Dave, The mounting of the bracket to the engine was done in about 20 seconds with almost zero thought put into it. If it was for a road car I would suggest following sideways suggestion and mounting it that way. It just wasn't critical for me so I didn't give it more than a literal few seconds of thought. You can likely do much better - it really just needs the bracket to be held securely to avoid "surging" caused by feedback if the motor is rocking in its mounts.

[DaveA]

Yeah, I like the fact that there's that 10mm bolt on the manifold sitting conveniently in just the right spot, but I'd be more comfortable if there was two!

Unfortunately, I "over think" these things and am very much "belt & braces" when it comes to these sorts of jobs

[DaveA]

Well, I ended up using a bit of stiff galv plate that was originally the bracket to wall-mount a clothes dryer . Works a treat!

I've used the single 10mn bolt on the manifold, & that seems good & sturdy for the moment. I really need to put a spring washer on though, & some loctite probably wouldn't go astray.

The only real hassle was that the "knob" on the end of the genuine (Indian knockoff!) Suzuki accelerator cable was too big for the Corolla carby. I had to disassemble the linkages so I could drill-out the hole. Note to self: take a photo next time BEFORE pulling the linkages apart!!!