EA81 Weber Conversion Writeup

[Sapper 157]

Okay, bear with me as this is my first write up, but here are the simplified steps to converting an EA81 from a Hitachi carburetor to a Weber carb... feel free to add anything i missed, and as always, referr to Jezek's thread if you dont find what your looking for here.

 

EA81 Hitachi to Weber 32/36 Conversation

 

NOTES: These instructions are for a no AC, non power steering 1.8L EA81; variations may apply to those engines equipped with said add ons.

The author takes no responsibility for misinterpretation of these directions and the consequences thereof. These are general guide lines that apply to all older Subarus equipped with the 1.8 liter EA81 engine. However, most steps will apply to the EA82 engine. There are some unique differences between the EA82 and the EA81, so if you're doing a swap on an EA82, please go to JesZeks thread here:http://www.ultimatesubaru.org/forum/topic/71510-ideas-on-swaping-a-weber-carb-on-ea82%C2%B4s/

 

Even if you are doing a swap on a EA81, I highly recommend looking at his thread, as he includes things which I have not covered in this write up, such as fabricating and installing a free flow muffler.

 

Terms:

PCV = Positive Crankcase Ventilation valve. The PCV vents harmful gasses away from the engine. It is found on the backside of the intake manifold next to the EGR.

EGR = Exhaust Gas Readmission valve. The EGR is an emission valve used to recirculated unburnt fuel vapors from the exhaust

ASV = Air Suction Valve. A useless emissions system that is supposed to suck cool air from the air box into the catalyst converter. It is easily identified by the large plastic silencers that attach to a shiny pipe that screws into each head.

12V Ignition Source: Any wire that has no more than 12 volts running through it when the ignition is on.

Throttle wheel: This is the part that the throttle cable (cable that goes from gas pedal to carb) hooks onto and controls the carburetor linkage shaft, which controls the butterfly valves, which ultimately controls the amount of fuel/air that enters the engine.

 

You will need:

1) Weber 32/36 DGEV Carburetor

2) Single Piece Adapter for EA81

3) Weber throttle cable bracket

4) Assorted rubber vacuum caps

5) JB Weld

6) Metric socket set and wrenches

7) Vise grips

8) Two quarters (.50 cents) or equivalently sized change or metal

9) A cutting device of some kind (hacksaw, Dremel, Sawzall, metal bandsaw, etc.)

10) Hitachi throttle wheel and washer

11) Nitrile/chemical resistant gloves

12) Carburetor cleaner/rags

13) Hose clamps

14) 4ft of 5/8" diameter rubber heater hose tubing

15) 1ft of 3/8" diameter fuel hosing

16) 1ft of 5/8" diameter vacuum hosing.

17) 5/8" plastic tee with a 3/8" contour CRITICAL THAT IT HAS A 3/8" CONTOUR!!

18) Drill with 1/2" drill bit

19) A few electrical connectors

20) Optional: Torque wrench, hi temp gasket maker, multimeter, egr Delete plate

 

Install preparation:

 

It is recommended that you replace the following in preparation for your Weber if they have not been done recently: spark plug wires, spark plugs, (use only NGK on both), distributor cap, distributor rotor, (be sure to use dielectric grease on all the connections), check battery and replace if old, check timing, if a solid lifter engine tune the valves, and change both fuel filters. I also personally HIGHLY recommend that you replace the throttle/accelerator cable, because after plus or minus 30 years, the plastic sheath that encases the cable has a tendency to crack and break when moved to its new location.

 

In order to achieve maximum performance from your carburetor, you must take the throttle wheel off of your Weber and install your Hitachi's throttle wheel in its place. to do this, gently remove the nut on the Hitachi and the Weber and wiggle the throttle wheels loose on each carb and remove them. Take the washer that was on the Hitachi shaft and place it on the Weber shaft, (apply a tiny bit of grease on the washer before install) Then slip the Hitachi throttle wheel on shaft and re-tighten the shaft nut.

 

WARNING! DO NOT OVER TIGHTEN NUT!! LINKAGE BINDING AND SHAFT DAMAGE MAY OCCUR!! To prevent this, tighten the nut until it is finger tight, then tighten one more flat of the nut with your wrench. Check the linkage for binding by working the shaft with your hand. If there is binding, loosen the nut and reinstall it at an even lower torque.

 

Your Weber will still run without the hitachi wheel, but the Weber wheel allows for only enough travel for the primary carb barrel to open. This means you are losing roughly 40% - 60% of your possible power.

 

Accelerator Cable P/Ns

 

4WD Models with EA81:

PIONEER CA8609

ATP Y639

 

Non-4WD w/ EA81:

BECK/ANRLEY 0950494

 

INSTALLATION INSTRUCTIONS

• Removing the Hitachi

1. Remove Hitachi Carburetor and all associated vacuum hoses

2. Plug all Hitachi vacuum ports and remove unnecessary metal lines beneath intake manifold.

3. It is highly recommend that EGR be removed and plugged. Here is the P/N for a delete plate if you cannot make one yourself out of aluminum. P/N: R66M-70978

4. Plug the carburetor coolant passage in the intake manifold with JB Weld.

5. Plug the coolant line leading to intake manifold with JB weld a cap with vacuum cap to ensure a tight seal. (The inlet is found on the metal pipe that leads to the water pump; it should be directly under the alternator.)

 

Positive Crankcase Ventilation (PCV) Setup

 

Link to 5/8" tee with 3/8" conture: "https://www.finditparts.com/products/596808/dorman-47147?srcid=CHL01SCL010-Npla-Dmdt-Gusa-Svbr-Mmuu-K596808&gclid=CjwKEAiA79zDBRCgyf2FgeiY-CESJABzr0BMo_otGbsQpbhMdDjmHM3Cs_I-O0hmXJbpxDmXr_fndRoCPsrw_wcB">https://www.finditparts.com/products/596808/dorman-47147?srcid=CHL01SCL010-Npla-Dmdt-Gusa-Svbr-Mmuu-K596808&gclid=CjwKEAiA79zDBRCgyf2FgeiY-CESJABzr0BMo_otGbsQpbhMdDjmHM3Cs_I-O0hmXJbpxDmXr_fndRoCPsrw_wcB

This can be found at any auto parts store... the link is just so you have a picture for reference.

 

6. Route the PCV line from the RIGHT head (drivers side) to one of the 5/8" sides of the chamfered tee.

7. Connect the other 5/8" end of the tee to the PCV valve.

8. Drill hole in the bottom air box plate big enough for the 3/8" hose or a fitting to hold the hose. (I used a 1/2" threaded plumbing fitting with a 3/8" barbed hose adapter)

9. Connect the 3/8" end of the chamfered tee to the bottom air box plate using the 3/8" hose

10. Connect the LEFT (Passenger side) 5/8" breather hose to the provided 90 degree tee that comes with the kit. This tee should be secured to the predrilled hole in the bottom of the airbox

 

Mounting the Weber

 

11. Clean off intake manifold and adapter mating surfaces using carburetor cleaner and rags (use 320 grit sandpaper if necessary)

12. Optional: coat mating surfaces and gasket in JB weld before installation. This will eliminate any chances of vacuum leaks and after all, youre not going to need to take off this adapter again unless you want to go back to the hitachi for some weird reason. A and if you ever need to transfer the carb to another car, a few blows with a soft faced mallet should break it free.

13. Mount adapter plate on intake manifold. Tightening in criss cross pattern, torque the 8mm hex bolts to 12 ftlbs or until reasonably tight. (Recommended use of blue thread locker)

Note: some members have welded their adapter plates on to completely eliminate vacuum leaks. If you are confident in your TIG welding abilities or know a good welder, this is certainly an option.

14. Screw the large studs into the top of the adapter (DONT USE THREAD LOCKER ON STUDS!!!)

15. Make sure carburetor and adapter mating surfaces are clean and dry. UNDER NO CIRCUMSTANCES SHOULD YOU USE JB WELD ON THESE SURFACES. USE JB WELD ONLY ON THE ADAPTER/INTAKE MANIFOLD SURFACE... NOT THE TOP OF ADAPTER TO CARBURETOR SURFACES.

16. I personally don't recommend coating the carburetor-to-adapter gasket with any kind of gasket maker/sealer... in my experience with carb gaskets, they cause more leaks than they prevent

17. Remove the brass "Y" shaped fuel inlet from the Hitachi carb and install on Weber carburetor.

18. Mount Weber carburetor on studs.

19. Mount throttle cable bracket on rear studs.

20. Tighten nuts on top of spring washers in criss cross pattern.

21. Mount the bottom air box plate to the weber and secure with provided bolts.

22. Hook up PCV system.

23. Wait 24 hrs for JB Weld to cure, then hook up the main fuel line and fuel return line to the Hitachi Y-shaped fuel inlet

24. Hook up electric choke and fuel cutoff solenoid to 12V ignition source (Test them first, but usually the connections to the old Hitachi choke can be used)

25. Connect the Weber's right vacuum port (should be under the choke) to the distributer vacuum advance (the vacuum port on the brass fitting mounted on the distributer) using the 1/4" vacuum hosing

26. Place the top air box plate on the air filter element and secure the two plates

27. Use your Hitachis throttle return spring as your Weber's return spring (or you can buy one at any autoparts store for a couple bucks). Finding a place to hook the other end can be a bit tricky, but I found that hooking it to a hose clamp near the Hitachi works well.

 

Deleting the ASV System

 

The ASV system is not a needed or required emissions system, so it can be deleted and plugged. The following steps will illustrate how to remove and plug the system.

1. Follow the steel pipe on each head to where the ASV connects to the exhaust Y-pipe underneath the engine.

2. Use vise grips or a large wrench in combination with PB Blaster to break the fitting loose.

3. After you have removed the fitting, loosen the bolts that hold the upper part of the pipe assembly on to the engine block

4. Remove ASV assembly

5. Use your method of cutting to cut the end off of each pipe and remove the hollow bolt that screws into the bottom of each head. (This is the one you needed the vise grips for in step 2)

6. Take a quarter (as in .25 cents)

7. Optional: coat quarter with Hi temp gasket maker to ensure complete seal

8. Place quarter into hole in the bottom of the head.

9. Screw in the hollow bolt until tight

 

You are officially done with the installation of your Weber conversion!! Your next step is to tune it for best lean idle, and to advance the timing. I have my timing set to 18 degrees BTDC. See a few posts down for instructions on that process. For more information on this conversion and for advice on how to modify the exhaust system to get even more out of your Weber, see Loyale 2.7 Turbos post on his EA82 Weber conversion. My guide here are simply the condensed steps, while he goes more in depth. I would HIGHLY recommend you study his thread thoroughly! "http://www.ultimatesubaru.org/forum/topic/71510-ideas-on-swaping-a-weber-carb-on-ea82%C2%B4s/">http://www.ultimatesubaru.org/forum/topic/71510-ideas-on-swaping-a-weber-carb-on-ea82%C2%B4s/

 

For additional mods to make your car even better, or if you want a different way of routing your accelerator cable in place of the Weber cable bracket, see Knucklehead Saloons post here: http://www.ultimatesubaru.org/forum/topic/165020-goodbye-pingtashi-hellooooooo-weber/?p=1370223

If you found this write up helpful please let me know! If you have a question or something is unclear, PM me or just ask it on this thread.

Edited November 3, 2017 by Sapper 157

[Sapper 157]

Here are a few pics for referance:

What the engine compartment will look like before the conversion:

All that can be removed during the conversation (EGR can also be removed but is not pictured)

What your engine compartment will look like after the conversion (sorry for the poor pic):

Edited October 31, 2017 by Sapper 157

[ihscout54]

Thanks for the contribution and nice work.

[Sapper 157]

Here is some info I found on Redlines website regarding Weber tuning. They say not to use a tuning instrument, however I find that I can tune all my carbs a lot more precisely by using a vacuum gauge hooked up to the manifold vacuum. So I will give the instructions that I recommend when using a vacuum gauge, then I will give Weber's instructions.

 

1. Ensure carb is set at baseline settings (2 turns out on mixture screw, 1 1/2 turns in on idle speed screw)

2. Using a 10mm wrench or ratchet, loosen the distributor bolt and advance the timing by turning the distributor to the right. You should see the vacuum increase and be able to hear the engine increase in RPMs. This step can also be done after your tune up, but then it is a good idea to reset the carb back to its baseline settings and retune it.

3. Warm up engine... it might run a little rough, but don't worry that's normal.

4. Hook up vacuum gauge to intake manifold (there should be two ports that were used for the Hitachi right on top of the manifold... I used the one that is closest to the carb on the left side)

5. With the engine warmed up, start turning the mixture screw out slowly. You should hear the engine smooth out, and you should see your vacuum climb from a shaky 14-15lbs to a rock solid 16+lbs.

6. Keep turning the mix screw out until you see a drop in vacuum... then screw the mix in for a 1/4 to 1/2 turn, or until your vacuum returns.

7. You can disconnect the vacuum gauge now and cap the port.

8. Now set your idle screw per Weber's instructions

9. Throw your car in gear and enjoy the increased HP, and overall drivability of the mighty Weber!

 

Weber's Tuning Instructions

 

Base line Settings

 

Speed Screw 1 to 1 and 1/2 turns

Mixture Screw 2 turns

Your settings with engine running

 

Speed Screw______________

 

Mixture Screw______________

 

 

 

 

 

It is important to follow all linkage and lever installation instructions. The number one and two reasons for tuning errors are improper linkage installations and over tightened linkage nut, causing a binding in linkage assembly.

 

CALIBRATIONS MAY VARY DUE TO REGIONAL FUELS AND STATE OF ENGINE TUNE AND PERFORMANCE. POOR RUNNING QUALITY DOES NOT MEAN A DEFECT IN THE CARBURETOR. AN ADVANTAGE OF THE WEBER CARBURETOR IS ITS EASE OF ADJUSTMENT AND TUNING.

 

SET UP ADJUSTMENTS

 

Start set up by confirming carb base line settings. Do not depend on the factory delivered settings. Check them before the carb is installed.

 

All settings are done with choke disengaged or warmed up so that the choke is fully opened and disengaged. This is done on automatic choke carburetors by first opening the choke butterfly by hand and inserting a wood block or wedge of some kind to hold open while the linkage is cycled (linkage operated through its full movement ) to clear the choke cam. (You will hear a metallic click as the cam is released. You can check the fast Idle screw under the choke assembly to confirm that it is not in contact with the choke fast idle cam.)

 

Set the Idle stop screw (speed screw see fig 1) by backing out the Idle speed screw until it is not in contact with the throttle stop lever. Cycle the linkage again to be sure that the linkage comes to close without any assistance. (Checking for linkage bind) Now bring screw back into contact with the lever and continue to open or screwing in 1 turn no more than 11/2 turns.

 

Set the mixture screw (see Fig 1) by first screwing in until the screw stops, bottoms out. DO NOT FORCE OR BIND AS THIS WILL CAUSE DAMAGE TO THE SCREW AND IT’S SEAT IN THE BODY OF CARBURETOR. Back out the screw 2 full turns.

 

TUNING

 

BE SURE TO FOLLOW THE NEXT INSTRUCTIONS IN THE PROPER SEQUENCE, DEVIATION WILL CAUSE THE CARBURETOR TO NOT FUNCTION TO ITS IDEAL SPECIFICATIONS AND MAY NOT PROVIDE THE PERFORMANCE AND FUEL ECONOMY AS DESIGNED.

Start the engine, the engine will run very slowly more like a tractor. As long as the engine stays running idle speed is not important at this point.

The first thing to do is not set up the idle speed, but to set the Idle mixture screw to lean best idle setting. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). The engine should pick up speed and begin to smooth out. Back out ½ turn more, or until the screw does nothing or runs worse then turn back to the point where it ran its best.

Use your ear, not a scope or tuning instruments at this point. You want to tune the engine by sound. Adjust to best, fastest and smoothest running point.

Now that the mixture screw is at its best running location, you can adjust the Idle speed the screw. The screw will be sensitive and should only take ¼ to ½ turns to achieve the idle speed you like.

Check and set idle to your driving preference. Put the car in gear and apply slight load, (AC on) and set the Idle as you like it. Don’t set it too high, as this will cause causes excessive clutch and brake wear. The Idle only needs to be 7 to 900 RPM with light load or AC on.

Recheck timing and vacuum hook ups. Recheck mixture screw to lean best idle again. If all is still best and smoothest idle then confirm and note the final settings.

To confirm settings with the engine running. Start by screwing in the mixture screw and count the number of turns it takes to bottom out and note if the engine dies. If Idle Mixture screws are with in ½ turn of base line setting then all is well and have fun. Also check the speed screw and note how many total turns from initial contact. You may have opened (turned in) the speed screw. Your final setting should be under 2 full turns. Reset the screws (back in) to the best final settings (Per your notes) and go on a test drive and have fun. If the settings are other than described then you may want to recalibrate the Idle circuit (low speed circuit) to your engines needs. This is done by following the rule of thumb BELOW.

 

 

Simple Rules for low speed calibration

 

If the mixture screw is more than 2 1/2 turns out turns then the Idle jet is too lean (too Small). When the mixture screw is less than 11/2 then the Idle jet is too rich (too large). These assumptions are based on the fact that the speed screw setting is not opened more than 11/2 turns. If the speed screw has to be opened 2 or more turns then this is also an indication of a lean condition usually requiring greater change. At times it may appear to be showing signs of richness or flooding it is really a lean condition. See pictures and notes in the tech 2 article supplied in the kit instructions, view and please understand the need to keep throttle plate as near to closed as possible so as not to prematurely expose the transition holes. This is what causes the visible rich condition, and confirms the need to increase the jet size. JET KITS are available if needed.

 

EXAMPLE With the speed screw set at no more than (1 1/2) turns in after contact with the stop lever; and the best idle occurring with the mixture screw set at 3 turns from bottom, indicates the need for a larger Idle jet. Achieving the best idle at under 2 turns indicates the need for a smaller idle jet.

 

The secret to understanding the critical nature of the carburetor set up and the advantages of a WEBER over other carburetors is the Idle circuit. Referred to as the low speed circuit by Weber, this circuit is responsible for 80% of the driving operation. This is the reason that the Weber should give a fuel economy improvement over most factory carbs along with significant performance gains. In the worst case you should not see a significant fuel economy loss over stock, while improving HP & Drivability.

 

The Weber Carburetor is a sequentially timed device to the motor like the distributor. Time taken in the setup will provide more fun later.

 

If you should need to call REDLINE for technical assistance we will need to know your final settings to help. Technical assistance is free for the first 60 days of purchase. Units in service over 60 days may be assessed a service fee. All charges will be noted up front after a brief consultation to determine any possible defect. If the carb is out of the warranty period and no defect is determined we will estimate the possible cost of tech support or recommend literature available that may help.

Edited July 16, 2017 by Sapper 157

[Sapper 157]

I also found this link to a Weber troubleshooting guide. I thought it might be useful for diagnosing some of the common quirks that may come up with the Weber

http://www.webercarbsdirect.com/v/vspfiles/images/Weber%20Trouble%20Shooting%20Guide.pdf

[rdweninger]

Congrats on your Weber swap.   I always knew you would get there ... eventually.   

  Thank you for the write-up.   I'm sure everyone appreciates your contribution.

[Sapper 157]

Write-Up Update

 

Several additions have been made to the condensed step guide for installation. Including directions for adding the hitachi wheel in the place of the weber wheel.

 

The following is a Q/A guide to the most common questions asked by those converting their cars, or those considering conversion.

 

Q: How much will a Weber conversion kit cost?

A. The USMB price for the EA81 and EA82 Kit is $320. The average price on eBay is $220 to $300. Carbs have also been found on craigslist for anywhere from $40 - $200

 

Q: How hard is the conversion?

A: The conversion is not difficult and can be completed by an entry level DIYer or mechanic, providing they have the proper basic hand tools and the needed materials.

 

Q: What fuel pressure does the Weber require?

A: The Weber must have NO MORE than 3-5 PSI of fuel. If the Hitachi Y fitting is used, then there should be no chance of over-pressurization of fuel.

 

Q: Will my MPG increase or decrease?

A: Generally speaking, a Weber that is properly tuned with the timing advanced will yield equal or better fuel economy. Realize though that the Weber provides a significant increase of fuel delivered to the engine. This is especially true if you floor it constantly, as this opens both the primary and secondary barrels. At most, you will see about 22 - 24 MPG with such driving habits. However, if smooth driving is maintained and the primary barrel is the only one used 80% or more of the time, you will see MPG similar or equal to that of your Hitachi. I get 26 - 31 MPH depending on time of year and driving conditions.

 

Q: What is the base jetting recommended for Webers used on Subarus?

A: For Old Gen Subies, the recommended jetting is:

 

Primary Air corrector--- 170

Secondary Air Corrector- 160

 

Primary Main Jet--- 140

Secondary Main Jet- 140

 

Primary Emulsion Tube--- F50

Secondary Emulsion Tube- F50

 

Primary Idle Jet--- 55

Secondary Idle Jet- 50

 

Remember, this is the BASE jetting, and your car may like something a little different. But thankfully, the weber is one of if not the most customizable carbs ever built, and jet kits are available on ebay for $50 -$70

 

Q: Is it difficult to tune the Weber?

A: Although I have only dealt with a few carbs personally (2BBL Hitachi, 4BBL Rochester and this Weber) the Weber is without a doubt the simplest and most rewarding carb I have ever tuned. They were built to be easily tuned, so they are really a breeze.

 

 

Q: Will the taller air filter fit?

A: It has been reported that the taller airfilter will fit on the EA82. There has been mixed success with the EA81. Some hood adjustments may be necessary. It barely fits on my 84' GL, and rubs the hood only a tiny bit.

 

QWhat are the P/Ns for the EA81 and EA82 Kits?

A: EA81 = K730

EA82 = K731

 

Q: Where is the built in filter screen located on the Weber?

A: The screened filter is located under a large brass plug just forward and underneath the fuel inlet fitting. It must be serviced every time you change the plastic (EA81) fuel filters or the metal (EA82) fuel filter. Or whenever the carburetor is rebuilt. A 19mm or 3/4" wrench or socket will remove it. DO NOT OVER TIGHTEN IT.

 

Q: What do I do with my EVAP canister?

A: You can either cap all the ports, except for the smallest tube that leads into the firewall. Or you can get rid of the canister, and just put a small fuel filter or something similar on the smallest tube that goes into the firewall. That tube needs to stay open as it is a vent for fuel tank.

 

Q: What should I set my timing to?

A: For EA82s, 20 degrees BTDC is recommended. For EA81s, 15 -18 Degrees BTDC is recommended. You will need a timing light.

 

Q: Where do I get an EGR blocking plate?

A: I just removed my EGR and traced the back of it onto a piece of .040” 5056-T3 aluminum and then cut it out with a die grinder cutting wheel. If you don’t have access to such materials (I am currently in college becoming an A&P mechanic so the supplies were readily available) then you can order one online. The part number for one that I know of is: R66M-70978 https://www.ebay.com/itm/151393859173

 

Q: Where do I get the throttle bracket for my Weber?

A: The P/N for the bracket from Weber is 99903.962, other members have also made their own with great success.

Edited March 16, 2018 by Sapper 157

[Leonesarebetterthanimpreza]

could I just put a filter on the PCV?

[Unknownjeremiah]

I have a K730 Weber kit from redline with the adapter plate and filter with the carb. 

$275

 

Pm if interested. 

[Steptoe]

Just my 2c worth for almost any Weber conversion using their air filter design

Due to the size of the filter assembly being way smaller than factory and the PCV fitting being small as...

I would include a catch can to connect up both left and right rocker cover breather hoses with their generous 19 mm ID ,and run a same size ID hose as the smaller PCV connector at air filter assembly.

Run a filter for air into crankcase on a T'd hose