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School me on EA81 DUAL-CARB engines


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39 replies to this topic

#1 backwoodsboy

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Posted 03 October 2012 - 09:20 AM

School me on the DUAL CARB EA81.


Ive done some searching, and have been gleaning bits and pieces here and there... but I havent found a definite source of information.

This has gone from a passing curiosity for me to a reality. I scored a set of dual-carb heads with matching cam and rockers/pushrods.


I have a solid lifter EA81 shortblock that Id like to slap the heads on once I change out to the dual carb cam.


It all looks very do-able, and I would ASSUME all the clearances/torque specs etc are the same.

Id rather save myself any unpleasant suprises though.

Anybody done one of these before?
Anybody have a book?

#2 ivans imports

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Posted 03 October 2012 - 10:09 AM

never a deul carb but just built a strong ea 81 for a hovercraft. we reground the cam used the bigger heads from a 87 chaser on the 81 solid lifter engine and put on a carb and intake from a 86 ea82 simplfyed down thiss engine worked realy good and i think the ea82 carb whould out pull the deul carb setup. we were shooting for 120 hp and i think we are realy close to that. was the snapyest ea81 iv'e seen even better than my TBI ea81.

#3 backwoodsboy

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Posted 03 October 2012 - 10:45 AM

Thanks for the reply.

Im no stranger to EA81 performance builds. This will be no exception.

Ive done 2 of em in the last 4 years with reground cams, port/polish jobs, upgraded carbs with bigger jets, and taller pistons. They can make really decent power if you want to spend the money and time.

I actually have no intentions of using the dual-carb manifold believe it or not.

The EA81 dual-carb engines make better power because the cylinder heads have a reverse valve setup than the standard EA81. They flow better = more power.

Edited by backwoodsboy, 03 October 2012 - 10:49 AM.


#4 the sucker king

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Posted 03 October 2012 - 10:51 AM

Do you have the intake? I have one that I will sell if I can't fit it on my car, I think it will not fit with the power steering pump. I will know soonish, drop me a line if interested.

#5 the sucker king

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Posted 03 October 2012 - 10:54 AM

edit- Sorry i just read your last post about the manifold.

Are you going to run 1 carb or fabricate individual manifolds? interested in what you do.

#6 the sucker king

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Posted 03 October 2012 - 10:55 AM

By the way- where in upstate are you? I grew up in New Lebanon, on the Mass border.

#7 backwoodsboy

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Posted 03 October 2012 - 01:00 PM

Im just outside of Oneonta (near Cooperstown/Natl baseball hall of fame)

Im thinking Ill do a ported/polished out EA82 carby manifold

#8 the sucker king

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Posted 03 October 2012 - 06:01 PM

Im just outside of Oneonta (near Cooperstown/Natl baseball hall of fame)

Im thinking Ill do a ported/polished out EA82 carby manifold


neato. my sister went to school for a year in Oneonta

#9 TOONGA

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Posted 03 October 2012 - 06:45 PM

The biggest difference with the Dual carby heads is the reversal of the inlet and outlet valves (on the true Dual carb heads) do yours have 2 inch or bigger exhaust ports? and a visible separator on the inlet port making 2 D's

as for available information all I can give is that I owned one of these motors for a few years. sadly I sold the car as I moved country (wish I never had now) And when I came back to Australia the car had vanished along with the motor :(

Inlet and outlet clearances are the same, not sure if you will need solid or hydraulic lifters, mine had solid.

Mine was mated to a 3.9 ratio straight cut 4 speed dual range box (came with the motor) and I was able to tune it to get between 95-100 km/h out of second gear.

Timing was set at 8 degrees any less and the motor ran like a chaff cutter, any more and it pinged its little head off.

they are a fantastic motor and will rev way higher than the normal EA81.

you will be amazed :)

TOONGA

#10 hatchsub

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Posted 30 November 2012 - 07:14 PM

I JUST caught this thread. Figures im out of the subaru world not even a year and you find what i was looking for all along for the coupe :banghead:. At any rate if you are to build it, you wouldn't be realizing its full potential with just the single weber on a ea82 intake. When i was looking and planning i decided that i would either make or have someone make me a custom intake that would mount dual carbs directly over the heads like some of the old VW crowd does. They would most likely be single barrel Webers of a bigger size than the secondary of the 32/36. That was what i figured would be the most fun with that car.

Oh another note give me a ring sometime. I havent heard from you or jess in ages. :)

#11 Caboobaroo

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Posted 30 November 2012 - 09:10 PM

I JUST caught this thread. Figures im out of the subaru world not even a year and you find what i was looking for all along for the coupe :banghead:. At any rate if you are to build it, you wouldn't be realizing its full potential with just the single weber on a ea82 intake. When i was looking and planning i decided that i would either make or have someone make me a custom intake that would mount dual carbs directly over the heads like some of the old VW crowd does. They would most likely be single barrel Webers of a bigger size than the secondary of the 32/36. That was what i figured would be the most fun with that car.

Oh another note give me a ring sometime. I havent heard from you or jess in ages. :)


The carbs came on the heads of the EA81 RX overseas. Seen an old brochure picture and in it they show a couple different shots of the engine.


Mmmmmmm....:popcorn:

#12 hatchsub

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Posted 02 December 2012 - 10:04 PM

The carbs came on the heads of the EA81 RX overseas. Seen an old brochure picture and in it they show a couple different shots of the engine.


Mmmmmmm....:popcorn:


Im pretty sure those were just the rally versions that got that setup.

#13 kiwi subbie

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Posted 02 December 2012 - 11:06 PM

Im pretty sure those were just the rally versions that got that setup.


I think thats the case. My RX has twin carbs on the manifold then it goes straight to the heads.
Not Carb staight to the heads.
My RX is nz new but has Japanese writing all over it.

Edited by kiwi subbie, 02 December 2012 - 11:09 PM.


#14 Loyale 2.7 Turbo

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Posted 03 December 2012 - 12:00 PM

The biggest difference with the Dual carby heads is the reversal of the inlet and outlet valves (on the true Dual carb heads) ...


Factory Twin Carb Subaru EA Engines were available on both the EA71 (1600) and EA81 (1800), Both engines were defined by a following "S" at the end on their engine codes. This was Subaru's way of calling it the Sports model. The engines were a completely different design to the standard models. The "S" models had Dual Ports and Opposite Valve configuration, which means different cams and rocker gear.

They were available in Japan in the Subaru Leone GSR and in the later RX Models. These engines has Higher Compression Ratio and had ~10% more power output. They were used heavily in the late 70s and early 80s Rally cars.




... When i was looking and planning i decided that i would either make or have someone make me a custom intake that would mount dual carbs directly over the heads like some of the old VW crowd does. ...



Posted Image


Do you Mean like This?
(this is an EA71):

Posted Image


Posted Image


I've seen such conversions, even done to EJ engines:

Posted Image


Usually done for VolksWagens

Posted Image




The carbs came on the heads of the EA81 RX overseas. ...


Yes!



...Seen an old brochure picture and in it they show a couple different shots of the engine. ...


Yes, it is this:

Posted Image


Posted Image


Posted Image


And this are Photos of the Car on the 1983 Safari Rally Race:

Posted Image


Posted Image


Posted Image


Posted Image



When Subaru Developed that Head-Mounted Twin downdraft Weber Carb EA81 engine with Reversed Valves, they already had the Turbo EFi Technology, so very Few of those were made, since Subaru started to sell the "Turbo Traction" Models in the same 1983 year...


Posted Image


Posted Image


But very Few Twin Weber Carb Models were Available for Sale, mainly in Japan and New Zealand,

like This one, which was for sale some months ago:



Posted Image


I'll Love to Own one of those Later Twin Carb RX!

Kind Regards.


Edited by Loyale 2.7 Turbo, 03 December 2012 - 01:33 PM.
To center the images ;)


#15 old sub freak

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Posted 04 December 2012 - 02:09 PM

Wow !!! I've been into Subarus for some time and have never seen anything like these's....WOW !! is right..Thank you for posting this stuff...Man they must have screamed !!!!! Well ,I have a duel carb set up on my 84 brat(the thrasher).Years back we were getting the import engines for like $400 bucks and I would go through the line of them with a breaker bar testing the compression by ear on the duel carb engines.They were the same price.I don't remember if I changed the engine out and kept the duel carb set up over the years? How can i tell if the engine is for duel carbs without taking off the intake ??I also remember talking to the guy that sold the import engines and he said the stock import carbs won't work over here(in the USA.I said that i have used the import carbs everytime and they worked fine.(For awhile we were swaping engines like starters..They came with everything carb,distributer ,everything, so all you had to do was drop it in , plug it in and it ran..)He just frowned and looked at his junk pile of import carbs that he had pulled and thrown on the junk pile....I have had the 2 carb set up for at least since 1997 and its still running.I did rebuild one carb 6 years ago..hey i know,I should have done both of them but...It worked and they still run so...??.Now lately i have thought of gettine 2 new hitotchi? carbs for it but I procrastinate. Mabey next summer...So , where is the engine vin # to see if I have a stock duel set up? C ya. OSF:banana:

#16 Loyale 2.7 Turbo

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Posted 04 December 2012 - 10:01 PM

Wow !!! I've been into Subarus for some time and have never seen anything like these's....WOW !! is right..Thank you for posting this stuff...Man they must have screamed !!!!! ...


You're Welcome!

I always thought that the Boxer Rumble Sound coming thru a Single Weber Carb in the Middle, Compared with the Boxer Rumble Sound coming thru Twin Weber Carbs, one on each Head, shall Be like Comparing Mono sound to Stereo sound... isn't it?

EA81S = the StereoBoxer! :lol:

Kind Regards.


#17 old sub freak

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Posted 05 December 2012 - 01:21 PM

So it should read E81 S on the engine block near the dist..? Thanks,Todd. Merry Christmas (If that applys) :banana:

#18 phantomD

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Posted 06 December 2012 - 07:47 AM

Nope, EA81 on the block, "S" imprinted in white on the rocker covers.

#19 Loyale 2.7 Turbo

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Posted 06 December 2012 - 11:02 AM

Yes, You can see the "S" (from "Sports") on the Cover, here:

Posted Image

Kind Regards.



#20 kiwi subbie

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Posted 06 December 2012 - 10:38 PM

Nope, EA81 on the block, "S" imprinted in white on the rocker covers.


I haven't noticed that on my RX. Will have to have a good look lol.

Did they do the same on the GSR with the S printed on the rocker cover?

#21 Loyale 2.7 Turbo

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Posted 08 December 2012 - 01:42 PM

... Did they do the same on the GSR with the S printed on the rocker cover?



As far as I know, the "S" Version came in the Sporty Models, However, Subaru did made other Sporty versions in the Past; the First EA81 Dual Carbs, had twin Hitachis on a Single intake manyfold, but those engines already got the Reverse valves, etc...

So the Twin Weber Carbs setup was the Last "S" Sporty engine with twin Carburetors from Subaru, in 1983; the same Year they intruduced the Turbo EFi engines, so very Few Twin carb EA81 engines where made, even fewer with the Late twin Weber Setup.


But subaru did the Twin Carb (Hitachi) setup Before, in the EA63 and the EA71.

Here is a Picture of the Twin Carb EA71 on the Subaru Manatee:


Posted Image


Posted Image


More info on the Subaru Manatee, on this Thread: "Strange & Weird Subaru Stuff"


Some EA63 Sporty versions, came with Weber Carb and Weber intake manifold:


Posted Image


Posted Image


Kind Regards.


Edited by Loyale 2.7 Turbo, 09 December 2012 - 11:41 AM.
Misspelled Word


#22 coxy

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Posted 09 December 2012 - 05:51 AM

First Subaru Twin carb engines were in the 1400 GSR coupe and GS Coupes from 1st December 1972 these were the EA63 type Engines in a more sporting Variant.
Weber Carbs were never fitted to any production Subaru but only available as a Sports option kit for Motorsport use and then only in very small numbers.

Australia was the first place outside of Japan where Subaru competed internationally in the Southern Cross Rallies in NSW,I should have some photos from back then I will scan and upload.
Here is also a Link to Subaru Philosophy,It can be not so intuative to navigate through to find information so I suggest searching via google or some other search engine for topics on the Subaru Philosophy site.
It is full of information not available in the past.
http://subaru-philos...632/leone-debut

#23 Loyale 2.7 Turbo

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Posted 09 December 2012 - 11:59 AM

... Australia was the first place outside of Japan where Subaru competed internationally in the Southern Cross Rallies in NSW, I should have some photos from back then I will scan and upload...


Great! ... Posted Image ... I'll Love to see your Photos from that Races! :burnout:

Kind Regards.


#24 Leeroy

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Posted 10 December 2012 - 09:48 PM

First Subaru Twin carb engines were in the 1400 GSR coupe and GS Coupes from 1st December 1972 these were the EA63 type Engines in a more sporting Variant.


The EA62 was available with twin carbs (in the FF-1) which pre-dates the introduction of the Leone in 1971/2.

#25 Loyale 2.7 Turbo

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Posted 10 December 2012 - 10:02 PM

I heard a Rumor about the Subaru FF-1 Star with twin Carbs and Disc brakes; I took a Ride once on a FF-1 Coupe, it had not the twin carb setup...

I Believe those came in different trim levels and variants for different markets.


EA62 1.3L OHV Water-Cooled Flat-4

Displacement: 82 mm x 60 mm, 1268 cc
Power: 80 bhp (60 kW) @6400 rpm, 73 ft·lbf (99 N·m) @ 4000 rpm with 9:1 compression and dual two barrel carburetors


~► http://en.wikipedia.org/wiki/Subaru_G

Kind Regards.

Edited by Loyale 2.7 Turbo, 10 December 2012 - 11:45 PM.
To add the Web Link.





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