The definitive(?) Weber conversion thread!

[Silverbullet]

As long as I've been on this forum I don't think I've seen a definitive "How to" thread on the Weber conversion. There are plenty of bits and pieces in various older threads but with few pictures and instructions and plenty of new members join just to ask how to convert their Brumby etc.

Well it's become an Easter tradition for me; the 4 day weekend means doing some sort of major conversion/heart transplant on one of my cars and this year I put a Weber on my Brumby. I took plenty of pics along the way and this is my "How to" thread on this subject. Please note this is how I did it based on the research I did, using various sources which I'll link to later on. This is not the only way to do it, just how I did it.


First of all you need at the very least a Weber and adapter plate. I used this website http://www.jameng.com/categories/Subaru/
And bought their "72-87 Brat" conversion kit. They are brand new carbies with
adapter plate included. They also sell jets on this website and I bought their
Weber 32/36 jet kit, with jets in 3 different "steps" for tuning. But so far it looks like the jets that come in the carbie are pretty well right, whatever size
they are. Also I think it's a good idea to get a fuel pressure regulator, although it may not be necessary. The Webers only really want 3 psi fuel pressure max, any more can upset them. I went to a local shop and got a 3.5 psi max, adjustable regulator. Try and get a single in/out in-line regulator. The shop I went to gave me a dual output T shaped thing, it was a complete nightmare finding somewhere to mount it and I needed to buy extra adapters and plugs etc.

If you are using the standard EA81 intake manifold that's already on your engine you won't have to worry about the next bit. But I decided to use an EA82 intake manifold from the later L series because of the larger intake hole where the carbie bolts up. Is there any benefit from this? that remains to be seen. If you decide to use the EA82 manifold then you'll also need to buy the EA82 adapter plate kit http://www.jameng.com/products/Subaru-B ... apter.html separately. Please note: This adapter plate kit is almost junk (poor quality) but I couldn't find anything else out there, and didn't have time to make my own so I had to make this one work. More on that later
I also bought this spacer
http://www.jameng.com/products/1%7B47%7 ... pacer.html
The idea with this was to insulate the carbie away from the heat of the coolant passage that runs underneath the stock carb. I don't think it's absolutely necessary, you can leave it out if you want. With the 2 plate adapter kit and this spacer it adds about 1 1/2" to the overall height of the carby. With the chrome air filter mine doesn't hit the bonnet.

[Silverbullet]

Intake manifold:
If you decide you want to use an EA82 manifold like me then you need to modify it slightly before it will fit up to the EA81 engine. Mainly lots of threaded bosses need to be cut off and vacuum lines plugged by either drilling out and tapping the holes for a plug or just using vacuum caps. The following link has another explanation on this conversion, it also has details on which bosses to cut off, which vac ports to plug etc. If you drill and tap the vacuum/coolant hoses be sure to use lots of thread locking/sealing compound. Also the heater return hose at the back needs about 30mm trimmed off of it to fit the heater return line back on.
http://www.angelfire.com/crazy/bushy5552/weber1.html
Modified EA82 manifold

Trimmed heater hose


There is also a coolant pipe that needs to be drilled out and plugged, or drilled
out and welded up. On the thermostat area of the EA82 there is a small barb that usually goes to a coolant barb on the engine block. On the EA81 it will hit the distributor so it needs to go. On the EA81 the coolant barb on top of the engine block needs to stay (to prevent air bubbles forming in the engine after you re-fill coolant) but gets re-routed to the heater return line at the back of the new manifold As for the coolant line at the base of the carb, you can drill this out if you wish and the coolant hose from here that connects to the barb under the alternator can be deleted. You can also weld the large coolant hole up if you have the means (TIG welding only!!)
Hole to be plugged

Coolant hose re-routed

[steptoe]

I'd like to see an idiot proof photo depicting where precisely all the different fuel and air bleed jets are. I have had a verbal just never sunk in, and surprise surprise, I am about to have a petrol EA81 on the road, have a 32/36 manual choke Weber hoarded just no adaptor plate. It came off a similarly tardy 1800cc so might be jetted just nice for the Brumby.

Good onya Sam. Glad you are doing light duty tasks over Easter ......oh, I see that is not a shadow, but a black rag. Used a red one today myself for similar purpose and thought of your mate

[Silverbullet]

Because the EA82 manifold thermostat is on the other side of the manfild compared to the EA81 the top rad hose is different. An L series lower radiator hose is almost a perfect fit as a top hose here, but it does touch the factory EA81 thermo fan if it is still there. I plan to replace this with a thinner aftermarket fan at some point.


That's about it for the manifold mods, on to mounting the carbie itself. If you are using an EA81 manifold then the adapter plate that comes with the carbie should fit (although there are 2 different sized bolt patterns on the EA81 manifolds, you man need to buy another adapter kit) If you are using an EA82
manifold then you need the 2 piece kit from Redline. As I mentioned earlier this kit is almost junk, and needs some work to be right. The two plates in the kit are just plain castings, they are not machined. This means the gasket mating surfaces were nowhere near flat on mine, and needed to be machined. I am lucky and have access to a milling machine and simply faced mine off, it took .2mm per side for them to clean up. If you don't have this luxury you may be able to get by using wet/dry sand paper mounted to a perfectly flat surface. Or if you know someone with a mill I'm sure they would machine them for you for a reasonable bribe.

Next the lower plate is mounted to the manifold using countersunk screws. There are 2 sets of countersunk screws in this kit and the larger headed black ones are the wrong thread for the manifold bolts. The smaller head stainless ones are the right thread but way too long and fit very poorly in the countersinks in adapter plate. I decided to use the larger diameter bolts and just drilled out/heli coiled the manifold to suit. If you do this be very careful not to drill any deeper than the original holes, in case you drill into the water passage. Bolt the plates up firmly using the included gaskets and I also used some silicone gasket sealing compound. Tighten the bolts in a criss cross pattern (these alloy plates are thin and flex easily) You can use Loc-tite if you wish but I did not in case I needed to take this apart again in the future
Machined adapter plates

Lower plate mounted up

Upper plate


Now you'll notice the massive mis-matches and steps between each adapter plate, and the manifold itself. I don't know what this would be like on the EA81 manifold but on this one they were atrocious. I couldn't leave it like this so I took to it with a die grinder and carbide burr.
DANGER DANGER DANGER!!!
If you decide to grind some meaterial out be EXTREMELY careful not to grind too much away at the front, you WILL break into the water jacket if too much is removed. Then welding is the only option or throw the manifold away. On mine there is very little standing between the intake tract and the coolant passage, I may yet have to remove it all again to get it welded up if it leaks.
Mis matched madness

All smoothed out

[Silverbullet]

You can bolt the carby up at this point but I would leave it until the manifold
is bolted up to the engine, it's just easier to see what else needs modifying
without the weight of the carby to deal with. The EA82 manifold is quite a bit larger in some aspects so some cutting was required on the alternator bracket. I also needed to drill out the manifold mounting holes .5mm bigger because the bolts were a bit tight when bolting the manifold up. Also the underside of the 82' manifold is very close to the engine block. Without the thick factory manifold gaskets it actually sits on the engine in the middle and rocks around. Make sure you use genuine Subaru intake gaskets! They are worth the effort. Again I used some gasket sealing compount because it doesn't hurt, and I like to be sure. Now is a good time to hook up all of your small coolant hoses and heater hose as well as the vacuum lines for your brakes, cabin heater controls and carbon canister (if you have one)
Alternator bracket

This coolant hose is an extremely tight fit, almost didn't make it

Next it's time to bolt up the carbie itself.

If you got the same conversion kit I did it comes with a DGEV carbie (electric choke) I mounted the carbie with the throttle linkage on the drivers side, and the electric choke at the front. The choke mechanism comes mighty close to the distributor but is still possible. If you can get away with it put the throttle on the drivers side, it eliminates so much complication when it comes to throttle cable and fuel lines. Again bolt the carbie down firmly and tighted the nuts in a cris cross pattern, tightening bit by bit. The electric choke needs a keyed 12V power source; take your pic of the ones from the factory engine wiring loom. I used the connection from the old anti-dieseling solenoid. Hook up your fuel line and if you have a return line hook that up too. The return line on my carbie was plugged, and didn't come with extra fittings so I just leave it plugged.
I re-routed this ignition lead to the rear of the carbie, it came too close to the fan belt/fan for my liking.

[Silverbullet]

Next is probably the part that gets the most questions and confusion. Connecting the PCV and crank case breather hoses. Since the chrome filter housing only has 1 possible connection for the crank case breathers many people connect both rocker cover hoses to this single port with a T piece. In my opinion this is wrong since in the factory set up air travels from the air cleaner into the drivers side rocker cover and out through the passenger side rocker cover and into the PCV valve, taking some filtered air with it from another air cleaner connection. I plan to adapt the factory air cleaner to mount on the Weber at some point and restore the factory PCV breather system, but that's a pretty involved job which I didn't have time to do this weekend. For now I have used the chrome filter and adapted the PCV hoses like this:

Drivers side rocker cover breather goes to the single connection on the chrome filter

Passenger side rocker cover breather goes to the factory junction piece and to the PCV valve. The smaller hose is the Carbon canister purge line (temporary)


That's all there is to the PCV hoses, until I update the thread when I convert the factory air cleaner to fit.
You will also have to figure out an accelerator cable mounting system. On the EA81 manifold you might be able to use the factory cable bracket. Mine went with my EA81 manifold but luckily there is a perfectly placed hole on the EA82 manifold to mount a cusom bracket. The throttle crank that came with my carby worked well with the factory throttle cable, but you can also replace it with the Hitachi throttle crank if you want to. I may still do this in the future as it has somewhere to put a return spring, the carbie as it is now does not return to idle sometimes so needs another return spring to slam it back.

[Silverbullet]

That's all there is to it! Well, almost. Now you just have to set up and tune the carby itself with the engine running. I followed the instructions that came with the carby for getting the base line setting on the idle speed and mixture. You need to do this with the engine at operating temp. On first start up mine idled too fase until I flicked the throttle and the choke opened up a bit. As the engine warms up the choke slowly opens until fully open at operating temp. On the idle speed screw mine barely needed to be touching the throttle lever to get it to 800rpm. You can't go more than 2 turns in after contacting the throttle lever since you'll open one of the enrichment tubes and this will mess up your idle mix setting.

On the idle mixture screw with the engine off (it's hard to reach this screw without getting in the way of the fans and belts) turn it all the way cockwise until it hits the seat (be VERY careful not to tighten the screw down on the seat, stop as soon as it touhes) and then turn it counter clock wise about 1 1/2 to 2 turns. I set mine in between there and it seems to idle pretty good. At this point I also checked my timing (which hadn't changed) and idle speed, bang on 800rpm.

Now take it for a test drive! the following website has quite a detailed explanation on what too look for when test driving. This part is all new to me so I couldn't advise on jet sizing and such. Whatever the jets are in the carby I got seem to be pretty good (it does say in the box that these kits are "pre calibrated" for the EA81 engine, whatever that means)
http://www.subarubrat.com/Retrofitting% ... V%2032.htm

When I drove mine I went from crawling long in 2nd gear and stomped on it to WOT and the engine did not bog down or want to stall out, it just accelerated. This I think is a sign that the main jet is pretty good. At around 60km/h in 4th it had no problem accelerating. At around 80km/h just cruising on the primary throat I stomped on it to open the secondary and get a tiny tiny hesitiation and bump when it seems to catch up and takes off. Some tuning is required here I think, maybe I need to fiddle with the mixture screw. In the past I had problems with the old carbie set up and the vacuum advance on the dizzy. Now I have a brand new carby and the dizzy is getting the proper vac signal it has brought out some problems in the dizzy, I don't think the advance mechanism is working properly so I plan to replace it soon. The only other problem was when I got home after the first drive the thermostat housing was leaking, probably my fault not letting the gasket sealing stuff go off properly. As for the water jacket at the base of the carby leaking well no sign so far and there is no water or steam/smoke in the exhaust. Time will tell if that fails and if it does the manifold has to come off again to get that hole welded up. I kept my old carby and manifold set up exactly as it was so I can just bolt it back on if needed.

So I've driven mine with a Weber for the first time and although it does rev higher easier and sounds a heck of a lot beefier under the bonnet, I must say there was negligible performance gain over my old set up. I'm not totally surprised by this since I think my old Hitachi was running about as good as they get, if not a little lean when going up hills at high revs. With the Weber pinging has definitely improved (I didn't notice any even under load) and hopefully the conversion will bring sightly improved economy and easier servicing/maintenence over the ageing leaky Hitachi.

So there it is! Hopefully this thread will be of help to some people and prevent new members from asking what's been asked a thousand times before. Overall this conversion cost me about $600, same as my 2 inch custom exhaust set up Time will tell if I get any better fuel economy, and hopefully the base of my carby doesn't leak! I'll update the thread when I convert the factory air cleaner to fit, but apart from that good luck to anyone about to do this conversion.

https://www.youtube.com/watch?v=8RJKAXy ... Qi4wbjrNdg
https://www.youtube.com/watch?v=WmX-cro ... Qi4wbjrNdg

[Silverbullet]

I'd like to see an idiot proof photo depicting where precisely all the different fuel and air bleed jets are. I have had a verbal just never sunk in, and surprise surprise, I am about to have a petrol EA81 on the road, have a 32/36 manual choke Weber hoarded just no adaptor plate. It came off a similarly tardy 1800cc so might be jetted just nice for the Brumby.

Good onya Sam. Glad you are doing light duty tasks over Easter ......oh, I see that is not a shadow, but a black rag. Used a red one today myself for similar purpose and thought of your mate

Jeez Jonno you must have been hovering just when I'm half way through posting to deliver the combo breaker

As for the jets I have no idea either, I think the two brass screws you can see down the side of the choke plates are 2 of them, and you must have to take the top of the carby off to change them. If I find I need to change jets I'll post some pics in here.

[olddog642]

Jeez Jonno you must have been hovering just when I'm half way through posting to deliver the combo breaker

As for the jets I have no idea either, I think the two brass screws you can see down the side of the choke plates are 2 of them, and you must have to take the top of the carby off to change them. If I find I need to change jets I'll post some pics in here.

Thanks for a great write up just what was need all the pertinent info in one place. As for Jonno hovering he is always lurking about somewhere ehehehe:twisted:

[Esubie]

A daunting task I hope I won't need to do.

[steptoe]

Didn't realise you had more to contribute immediately, deleted my post from the flow of things

I like your honesty in not much of an appreciable improvement on your Hitachi. When the dealers were faced with no chokes available no more for the Hitachis - they fitted Webers - so guess they are an almost official Subaru option.

I know some have said a Weber is as good as twins - sort of doubted it, but your comments strengthen my thoughts

I recall when I put my twins on - awesome sound of quad throats - sounded like a 2.0 (Kombi )

The real benefit was out on the highway up in the NT where 140kph was once possible to sit on legally, and had plenty of pedal to go LPG sort of killed that pep. Coincidentally, my fuel gauge developed faster travel towards the E , yet thankfully was just a quirky thing, think I could still do 8.0 or 8.5's

Pulled impressively better than the single carb that had been kitted not long before

[Silverbullet]

The thing is these cars are so old now and all been treated differently each car is different. So when one person says their Hitachi is rubbish, that's unique to their car but my Hitachi (rebuilt recently) was running like a swiss watch so the Weber is only a slight improvement. And the Hitachi that was on the engine in this ute when I bought it drove half as well as the carb and engine I put in it. In any case compared to when I bought it this ute drives 10x better, just the recurring CV joint nightmare to fix but I digress

Like I said I think it performs better at higher RPMs and gets up there easier than the old carb probably due to more air flow? bigger throats? Maybe my EA82 intake manifold with larger intake hole has made some difference. I'll report back after a week of driving it to work to compare fuel economy; last full working week I used 25L of 98 RON for 300k travel roughly.

[Subydoug]

Nice Write-up Silverbullet. Should definitely point some others in the right direction. My Hitachi was utterly rooted when I did my swap. Self tapping wood screws were abundant . I didnt worry about the heat inhibiting spacer and I modified the stock airbox to fit on the top. Keep an eye on your mounting nuts as mine have worked finger tight before. I find in general I never use the secondary butterfly as it seems utterly pointless and it lacks a pump jet, the result being a flat spot as the secondary opens up that is near on incurable.

Regards

Doug

[steptoe]

and looking at those pics, I wonder if the electric choke would clear the dizzy cap if you did not use the two pieces of the adaptor plates ?

300km in the EA82T sedan guzzled 45 litres of 109 !( LPG ) A third of that was hauling a trailer loaded up say 300- 600kg .... which prompted me to try a leaning ring ( $5 ? ) to bring pre cat mixtures down a little more. The original EA82T cats are a very efficient little air cleaner. The resulting fuel efficiency won't be known until the gear ends up in the lighter Brumby though...new project clock ticking soon....

[Esubie]

The thing is these cars are so old now and all been treated differently each car is different. So when one person says their Hitachi is rubbish, that's unique to their car but my Hitachi (rebuilt recently) was running like a swiss watch so the Weber is only a slight improvement. ....

Thanks for making that good point.
My L came to me through my family and my Bro had a kit put into the carb before I got it so it's going fine. However tempted I am to try 'improving' it I think I'll leave it alone since there's nothing at all wrong with it.

[FujiFan]

Hmm nice work SB. I'm sure I've seen that manifold somewhere before

Really good what you have done and are doing. Love how you have cut off all the unnessary casting lugs n what not from that manifold. Just what I would do:D

J.

[steptoe]

I really wanna see something else we have seen before - bloody hurry up Sam !!

Good work

[Silverbullet]

Thanks Jay yeah that should look familiar

I really wanna see something else we have seen before - bloody hurry up Sam !!

Good work

I'm planning to take a week off work soon, come hell or high water that will be the week of the paint job, and you'll see the twin port by the end of the year I promise

[Silverbullet]

Here's a couple of quick shots of how I have the throttle set up now. The crank that came on the weber had nowhere to put a return spring and it definitely needs one so I put the old Hitachi crank on it (needs a spacer behind it to clear some of the linkages) And yes I know it looks totally bodged up having the spring hooked over a loop of wire It's just a perfect place to put it until I can work something else out, maybe I can use one of those 3 screws on the choke housing. Happy to report no further coolant leaks after I fixed the T-stat housing leak and no steam or smell in the exhaust so no internal leaks.

Cable bracket was quickly made up from some thick stainless, twisting the strip made it less flexible. It could do with being a bit lower however.

And after further testing and tweaking I'll revise my previous opinion on the Webers performance More improvement than I previously thought in the torque department and the car gets up to 100 and wants to keep going where the old carb would start to run out of breath. And with the extra noise under the bonnet this is definitely a worthwhile mod IMO. I'm thinking of fitting an exhaust gas analyzer in here somewhere to see what it's really running like, maybe put a sensor in the exhaust somewhere.

[henpecked]

Great write up , really impressed that you took the time to get the photos done and post it all up for others to use.