Ideas on Swapping a Weber Carburator on a Subaru EA82 Engine
In this Writeup:
► Solving problems untold by the Manuals.
► Weber 32/36 Jetting for the EA82 to be used between Sea Level and ~ 6500 Feet (2000 Mts) Altitude.
► Proper PCV (Positive Crankcase Ventilation) Hoses Setup and installing an (optional) Oil Catch Can.
► A much better Adapter Plate than the Traditionally used on Subarus.
► Intake manifold modifications (optional).
► ...and Much More! Pay attention to the "Important Notes"
Some time ago, I did Swapped a Weber 32/36 Carburator on my 1985 White Wagon EA82 (which isn't white anymore) That swap job took much more things to do than the Weber's Manual describes; so I'll explain and add Pics of all the problems I found and the ideas to solve 'em, here; Hoping that those will Help People who want to Swap a Weber carb in a EA82 Subaru engine... However many of the Ideas I'll explain here, might be aplicable to an EA81 engine too, everything might apply to the EA81 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 carburator on the Subaru EA82 carburated Engines, comes with a Progressive Weber 32/36 Carb, an Air Filter Box plus its element, a Throttle Cable Bracket, some Gaskets and a two plate Adaptor, which consists on one Lower plate designed to be mounted directly to the intake manifold, and one upper plate, designed to be mounted over that first plate; this last one will have the studs which are intended to Hold the Weber Carb in place; and needs the Gaskets inbetween...
Well, All those Webers that are Sold in 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 that 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 Carbs, due to said Legal Regulations.
There are many different Weber Carburators' Designs on the market, however the two models used more often, are the Progressive Models (Such as the 32/36 DEGV I used) and the Synchronous Models (Such as the 38/38 DGAS), if you want to be Sure which model do you have, just take a look at the Linkage between both Stages, behind the acceleration plate: If Both Butterflies moves at the same time, all the time the Throttle position moves, it is a Synchronous Weber (Such like the 38/38 DGAS or a bigger numbered, like the 48, etc...), But if one stage opens after the other have reached already half way open, then it is a Progressive Weber. (such like the popular 32/36 DEGV I Used).
The Synchronous Webers, such like the 38/38 DGAS are more used to Racing purposes due to the Higher Fuel usage (Both Huge Jets works / opens at the Same Time, all the time), and thus means that if you use a Car with such kind of carb as daily driver, it will be a Gas guzzler, compared to the Progressive Webers, like the 32/36 I Used, where you commute with only one stage (with the Smaller Jetting), usually; and the High stage (with Bigger Jetting) is used during deep acceleration only, so you have the Best Balance between Power and Fuel Consumption.
That been said, lets Begin to explain the Problems I Faced during the Swap Job, and How I Solved them.
--► First Problem: The Screws that Holds the Lower Plate.
The lower plate needs four screws to be Held properly in place; each screw has a countersunk head with a flat top surface and a cone-shaped bearing surface with a head angle of approximately 90° designed to fit on the cone-shaped hole on the Lower plate, letting the screw's Head to be as Flat as the lower plate's Surface itself and the inner angles holds the plate firmly in place.
But it is impossible to bolt in a "Secure" way the lower plate to the intake Manifold without doing some modifying job, due to the fact that the size of the Manifold's Threads for the original carburator's Screws are smaller than the size of the screws designed to hold the Lower plate properly. So, the K-731 Kit Comes with two sets of Screws for the Lower plate ... ... Let me Explain why:
♪ One set of four screws with the Smaller diameter Size: they fit right on the intake's threads but their heads will be loose on the lower plate's cone-shaped Holes by around 5 mm (3/16"), that loose fitting will lead to vacuum leaks sooner or later, because they permit some minor "Movement" on the lower plate, as they loose their tightness...
These Smaller diameter size screws are intended for the mechanic who only wants to install the kit as fast and easy as possible, and get rid of the car; even knowing that it will develop vacuum leaks and other problems sooner or later ... ...
♫ The another set of four screws does come with the proper size for the lower plate's cone-shaped openings, so these screws has a Bigger Diameter; their heads will fill and match perfectly the Holes in the lower plate, avoiding any chance of Looseness or movement, But they will not fit the threads on the intake manifold...
These Bigger diameter screws are intended for the one who wants to do a well done, reliable swap job.
So, My Solution was to use the Bigger Diameter Screws, of course!
(But continue reading: in further posts of this writeup I'll show you a more safe & Definitive way to solve this problem)
To make those Bigger diameter screws to fit, You'll 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 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, with the Craptachi Carb & Gaskets just Removed:
(Notice the Small threads on the Carb's Base)
So I took off the whole intake manifold to Drill the New Oversized Threads
From 6 mm (around 1/4") to about 8 mm (around 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 Screws Now does fit perfectly on the Subie's Intake:
Then, I Washed clean the intake manifold using Household Detergents, to remove any debris:
Important note: All the inbetween gaskets should be placed completely Smeared (the two faces) with Shellac, because shellac is Coolant / Oil \ Gasoline Resistant (more info on Shellac ~► Here) other gasket makers will fail in that place.
--► 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 cutted in half the tiny Hose which supplies coolant for that Passage, and cap closed both cutted ends using screws and clamps... That worked fine for years but you must consider that there is coolant flow inside the water crossover on the intake manifold; so there still will be coolant flowing on that Area, even with the removed hose.
You might use Cold Welding Compound 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 was about to Fail... 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 Shellac Smeared gasket, I installed the Lower Plate:
(Notice the Bigger Screws and how their Heads remain Flat on the Plate's Surface)
Then, the Upper plate over that, with a Shellac Smeared Gasket inbetween:
And Then you can place the Weber Carburator.
--► Third Problem: Power Steering Equiped Models.
If your EA82 engine does have 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.
(the Choke spring was already Removed from the Weber Carburator)
Here at the Caribbean Tropics we don't need the choke, so my first solution was to Remove the Choke's Spring, but also I Needed to cut Half of the head from one of the Steering Pump's Rear Bolts to avoid the Base for the said spring from hit the power steering's back bolt. ... Another Solution is to Completely Remove the Choke's Spring Base from the Carb and its Butterflies (choke plates), so you'll not need to cut anything. Continue reading, because in further posts of this writeup I'll show you yet another and better Solution I found.
Important Note: I did installed on the Weber Carb, the Accelerator Cable Plate Taken From the 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.
So the Intake Manifold + Adaptor Plates + Weber Carb 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 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! ... resumed in quicker Engine Response and Faster Acceleration, smoother Idle and a 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...
Edited by Loyale 2.7 Turbo, 18 August 2013 - 10:03 AM.