Ideas on Swapping a Weber Carburetor on a Subaru EA82 Engine
In this Writeup you'll find
► A complete installation Guide.
► Solving problems untold by the Manuals.
► Jetting for the EA82 to be used between Sea Level and ~ 6500 Feet (2000 Mts) Altitude.
► Proper routing for the P.C.V. (Positive Crankcase Ventilation) System's Hoses.
► A much better Adapter Plate than the one designed for the EA82.
► What to do with the ASV, EGR, etc...
► Installing an Oil Catch Can on the P.C.V. System.
► Distributor's Advance Modifications.
► intake Manifold Modifications.
► ignition Coil upgrade.
► Exhaust Piping Modifications.
► ...and Much More! Pay attention to the "Important Notes"
On early 2006 I Swapped a progressive Weber 32/36 Carburetor on my 1985 Subaru White Wagon (which isn't white anymore),, that swap job required more things to be done than what the Manual included with the kit, stated; so I'll explain here everything that is needed to successfully do the Swap, and I will add Photos describing all the problems I faced and the ideas I had to solve them; Hoping that this writeup will Help you to Swap a Weber carburetor on an EA82 Subaru engine, flawlessly.
Many of the Ideas that I explain here, are also aplicable to the older Subaru EA81 engine as well, basically talking, almost everything except the adapter plate.
REMEMBER: Use this Ideas at your Own Risk!
First of All: the Redline-Weber K-731 Kit, which is designed to install a Weber carburetor on the Subaru EA82 carbureted Engines, came with the following items:
A Progressive Weber 32/36 Carburetor, an Air Filter Box plus its element, a Throttle Cable Bracket, some Gaskets and a two plate Adapter, which consists on one Lower plate designed to be mounted directly to the intake manifold, and one Upper plate, designed to be mounted over said Lower plate; this last one receives the studs which are intended to Hold the Weber Carburetor in place; and needs the Gaskets inbetween ... Also this kit, comes with a bag with different screws and the studs.
All the Weber carburetors that are Sold in the USA, comes with a sticker with a Statement that says something like: "For Racing -or Offroading- Purposes Only" due to Smog, pollution and other Legal Regulations which varies from State to State, so They're Not "Street Legal" on certain areas and that statement shall be placed on all brand new Weber Carburetors, due to said Legal Regulations; so you must be sure that you are legally allowed to do this Swap on the Area where you Live, prior to start.
Determining which type of Weber carburetor you do Need
There are many different Weber Carburetors' Designs on the market, however the two models used more often on Subaru Engines, are those who features two Barrels. (Forget about using a single barrel carburetor on these Subaru engines, simply it doesn't worth the effort.)
Basically talking, there are two variations of the two barrel design on Weber Carburetors, that works good with these Subaru engines, one design is known as the Progressive Models (being the most popular, the 32/36 DEGV) and the other design is known as the Synchronous Models (being the most popular, the 38/38 DGAS).
Each of the two barrels, has its own butterfly that opens / closes according to the Throttle position; if you want to be Sure which model you do have, just take a look at the Linkage that opens the butterflies between both Barrels, it is located behind the throttle plate: If Both Butterflies on both barrels, opens at the same time, always when the throttle position moves, it is a Synchronous Weber (like the 38/38 DGAS); But if one barrel's butterfly starts to open only after the other one have already reached the half way open, then it is a Progressive Weber. (like the 32/36 DEGV).
The Synchronous Webers, like the 38/38, are used mainly for Racing purposes due to the Higher Fuel usage (Both identical barrels works / opens at the Same Time, all the time), and thus means that if you use a Car with such kind of carburetor as daily driver / commuter, it will become a Gas guzzler.
The Progressive Webers, like the 32/36, are used for all mixed driving needs, as you commute using only one barrel which is known as the Primary -Low- Stage (usually with a Smaller Jetting); and the other barrel, which is known as the Secondary -High- Stage (usually with a Bigger Jetting) is only in use during deep accelerations, so you have the Best Balance between Power and Fuel Consumption.
I chose a Progressive 32/36 Weber carburetor, which is, in my own humble opinion, the best option in Carburetor that you can choose for this retrofitting job; however this writeup is still applicable, if you have a synchronous Weber.
That been said, lets Begin to explain the Problems I Faced during the Swap Job, and How I Solved them.
~► First Problem: The Lousy Adapter Plate.
As I stated above, the K-731 kit that I obtained from Redline Weber, came with a Lousy Adapter, conformed by two separate Plates, Lower plate and Upper plate, each one has its own flaws ... ...
The Lower Plate needs four screws to be Held properly in place, directly bolted to the intake manifold; each screw has a cone shaped, flat top head, whose angle is approximately 60° and is designed to fit on the also cone-shaped seats of the plate's openings; the matching angles holds that plate in place. Then comes the Upper plate, which goes directly bolted to the Lower plate; finally, the Weber carburetor mounts on that Upper Plate.
The Flaws of the two-Plate adapter:
While the weak thin walls on the threaded openings for the Studs, is the main flaw on the Upper plate, (Look for further information and photos regarding the Upper plate, on the following post of this writeup); the way to bolt the Lower plate to the intake, is another flaw, let me explain:
The Redline-Weber K-731 kit came with two different sets of screws provided to bolt the Lower Plate of the adapter, to the intake manifold; one set of four silver screws, comes with the appropriate size and pitch for the Subaru EA82 intake manifold's threads (6 mm ~ 1/4"), but the heads of those thin screws are very small, around the half size of the cone shaped seats on the lower adapter plate.
The other set of four black Screws provided, are thicker (8 mm ~ 5/16") and their heads fills completely the cone shaped seats on the lower adapter plate; but their thread and pitch are big and do not fit on the intake manifold's threads.
Here you can see a comparison photo, of one of the silver 6 mm screws (I call it "Subaru Standard" screw) provided, next to one of the black 8 mm screws (I call it "Weber Special" screw) provided, for the same Lower plate:
(sorry for my Cheapo Cellphone's camera photo)
It is impossible to bolt in a ►"safe"◄ way, the Lower plate to the intake Manifold using the thinner 6 mm screws provided; but I bet that they included both sets, in order to let the unexperienced or Lazy mechanics / owners, to swap the carb fast and easy.
Those tiny silver screws will make the first plate to get Loose, developing vacuum leaks sooner or later, because their small size, makes the screws to have enough room inside the plate's opening, to move and slowly unscrew, from the engine's inherent vibrations; it's only a matter of time. Also the tiny silver screws only covers half of the seat, on the openings of the lower plate, making a weak union.
I already faced a vacuum leak: I was unexperienced when I did my first Weber swap, years ago, and I used the tiny silver screws as they matched the threaded openings on the intake manifold... it developed a Vacuum Leak between the intake and the lower plate, in less than a couple of months, despite that it was bolted tight, using a shellac smeared gasket.
After that vacuum leak, I removed the intake manifold to check the install, and then I understood the reason why they put a second set of screws by seeing how loose the Lower plate became with the tiny silver screws... I decided to use the Bigger diameter black Screws, instead.
In the Photo Below, you can see how the Heads of the silver 6 mm (~1/4") screws, doesn't fit properly on the cone shaped seats of the lower plate adaptor; they only covers the half from the cone seat and their heads doesn't fill completely the space of the opening in that plate.
Next to it, you can see how the Heads of the black 8 mm (~5/16") screws, really fits perfectly there, they sits on the whole cone shaped base, while filling completely the opening, giving a much safer flush mount, which prevents the screws from getting loose with time and vibrations, as they doesn't have space for moving, because the Upper plate will be placed over them.
So, some modifying job to the intake manifold is required for sure, if you want reliabilty: to drill and tap it, re-threading the intake manifold's threads to match the size of the bigger black screws provided, in order to use them to bolt the Lower plate properly, and firmly in place.
To make those Bigger diameter black screws to fit, You will need to Drill and tap new Bigger Threads to the intake manifold, but Be Careful when doing that: The intake manifold is also a coolant crossover, so you must take the proper depth measurements to avoid drilling onto a water passage. I Kindly Suggest you to remove the whole intake manifold from the Engine, prior to do the rethreading.
Here you can see how the intake Manifold originally was, right after removing the old Craptachi carb and gasket, just before removing it from the Engine:
I took off the whole intake manifold to Drill the New Oversized Threads
From 6 mm (~ 1/4") to about 8 mm (~ 5/16")
Also I Sent the intake manifold to a Machine shop, to polish the flatness of the Carb's base:
Here, you can see how the Bigger black screws Now fits perfectly there:
Then, I Washed clean the intake manifold using Household Detergents, to remove any debris
Important note: I kindly suggest you, that the inbetween gaskets should be placed Smeared (the two faces) with a thin layer of Shellac, because shellac is Coolant / Oil \ Gasoline Resistant (more info on Shellac ~►Here) other gasket makers will fail in that place; the idea is to avoid any kind of Vacuum leaks.
~► Second Problem: To Seal the (Now Unused) Water Passage for the Old Craptachi Carb.
If this procedure is not done right, the cooling system will spill coolant on the intake manifold, right to the carb's base opening, so be Careful!
My first solution was to place the Gasket completely smeared with Shellac over that water opening, and also I cut in half the tiny Hose which supplies coolant for that Passage, and cap closed both ends of said hose, using screws and clamps... That lazy solution worked fine for five years, but you must consider that there is still a coolant flow inside the water crossover of the intake manifold; so there still will be coolant flowing on that Area, even without said hose.
You might use Cold Welding Compound such like the 4 minutes "JB Weld" to fill close that opening ... as I wrote, I ran my subie for years with only a Shellac smeared gasket and a removed hose without problems, but that setup was about to Fail after five years. Continue reading, in further posts of this writeup I will show you another Idea which is a definitive and permanent solution for this problem.
After placing the Gasket, smeared with Shellac on both sides,
inbetween the intake and the first plate, I bolted it there:
(Notice the Bigger Screws and how their Heads fills the Plate's openings)
Then, the Upper plate went over that first one,
Also with a gasket smeared with Shellac on both sides, inbetween:
And Then you can place the Weber Carburetor.
~► Third Problem: Power Steering Equiped Models.
If your EA82 engined Subaru, has a Power Steering Pump, the Choke's Spring mechanism on the Weber Carb, will hit the Power Steering Pump's reservoir ... ... and even removing the Choke's Spring, the base for the said spring, impacts the bolt's head at the back of the power steering pump.
(Here, the Choke spring was already Removed from the Weber Carburetor)
At the Caribbean Tropics of Honduras, we don't need the choke too much, so...
► My first solution was to Remove the Choke's Spring, but it wasn't enough: also I had to cut Half of the head from one of the Steering Pump's Rear Bolts, to prevent the Base for said choke's spring from hitting it.
► A second Solution consist in, besides from removing the above mentioned Spring, to Completely Remove its Base from the Carb, along the choke's Butterflies (or choke plates), so you don't need to cut nothing.
► A third solution done by other persons, is to install the Weber Backwards, with the Choke facing the windshield instead to the front; it is doable, but in my own humble opinion, it might lead to another complex set of Problems. You can see photos and read further, in this example:
► After lots of Research, I found a fourth and definitive Solution, which is easier than all the others.
Continue reading, because in the next posts Nº 2 and 3 of this writeup I'll explain with details this better Solution ... ... which does Not require to modify, to cut nor to remove anything, so you can keep the Weber carburetor with a working Choke on the Models that features Power Steering, as easy and simple as install and go.
Hooking properly the Accelerator Cable
I installed on the Weber Carb, the throttle's Cable Plate Taken From the old Craptachi carb...
...Plus the part of it that works with the Air Conditioner Accelerator Actuator, which with a simple twist on its metal plate (due to the new carb's different angle) I managed to made it work good.
The K-731 kit from Redline-Weber, also includes a Bracket to hold the Accelerator's Cable in Place, you must install it Carefully without Bending it, on the two rear screws that holds the Carburetor, on the Adapter plate; and you'll notice that the Accelerator's Pedal really covers the complete Acceleration Travel on the Weber Carburetor.
In case said Bracket is bent Towards the Carburetor, the accelerator's Pedal will never get the Full Acceleration from the Carburetor because the Cable doesn't go Back enough to fully Open the Secondary -High- stage; in that case you'll need to bend it back; but Never do it when it is installed, it could damage the Adapter Plates; so take the Bracket out and bend it there. Once the Bracket is properly set, the accelerator pedal provides full travel for the accelerator on the Weber carburetor.
So, the Intake Manifold + the twin Adapter Plates + the 32/36 progressive Weber Carburetor + the accelerator cable's Bracket behind, ended looking in this Way:
(Yes: Those are my dirty Hands)
Once installed, the EA82 Engine started at the Very First Try and Purred like a Kitten...
a Boxer Kitten! ... ... you know.
The Weber carb reveals somehow the Hiding potencial of the engine, and the Boxer Rumble Sound of the Carburated EA82's at its Best! ... ... While lets you Clean the crowded engine bay, removing lots of unused smog stuff. It is a Win-Win Deal for sure.
I Noticed a Huge Improvement inmediately! ... Summarized in a quicker Engine Response and Faster Acceleration, smoother Idle and a really noticeable Better Low end torque.
Fuel Consumption remains close to the Stock Specs ... (if you drive carefully) ... but the Weber swap could make you to want to keep the gas pedal floored ... ... in that case, fuel consumption will increase for sure
Edited by Loyale 2.7 Turbo, 08 October 2016 - 02:00 AM.