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Hitachi adjustments... I know it's all been said b4


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46 replies to this topic

#1 Subaru_dude

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Posted 13 November 2012 - 03:15 PM

The one thing I can't find is which screws do which... GD in a writeup speaks of the screw behind the pin at the bottom front of the carb. I guess it's the idle mixture screw, that's what he refers to it as. I turned it all the way to the right and then back out 2.5 turns and it does indeed run. The idle is a little high (was running 2500 warm but after cooling now running 1200, haven't gotten it warm again) and I can't seem to find in any of my searches where the idle adjust screw is? I found the screw that presses against the linkage to hold the idle up but it's not even touching the linkage and there's also slack in the throttle cable. Are these the only 2 screws I need to play with? I thought there was a mixture/air screw too but doesn't seem to be the case. This carb was de-emissioned, it ran OK before but had intermittent high idle issues. It is a feedback carb that was on an EA71 and is now on an EA81. I thought the carbs themselves were the same as the normal EA81 carbs except for all the extra hoses on the outside of it. Figured getting rid of all that stuff wouldn't hurt anything. The feedback computer is unplugged. Also, there's a metal line that comes out of the exhaust behind the trans and runs into a rubber line that runs up next to the trans to a big black UFO looking thing, and that hooked into the air cleaner. I just have that plugged off now.

Anybody know if the EA71 feedback carb is any different from the plain jane carbs on the EA81s? My feedback is indeed a 2 barrel Hitachi.

#2 djellum

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Posted 14 November 2012 - 02:56 AM

normal hitachi's require all the plumbing to work perfect, but will run well without them. a feedback will likely need all its plumbing, or at least the associated sensors and computer, to run at all.

the ea81 hitachi's are different than the ea82, though i dont know what years and what specifics other than the ea81's were slightly smaller cfm.

someone with more expierience with the feedbacks will chime in im sure.

the 2 screws are the ones your looking at. center is the air fuel and the one on the linkage is the idle. in general until your choke dissenges when the motor is warm the actual tuning cant be done. theres probably a 3rd screw which is your choke adjustment. on a more basic setup i would dissengage the vacuum to the choke while doing the actual adjustment, then hook it up and tune it after, but with the feedback I have no idea what it might be doing for the choke.

#3 Subaru_dude

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Posted 14 November 2012 - 02:15 PM

normal hitachi's require all the plumbing to work perfect, but will run well without them. a feedback will likely need all its plumbing, or at least the associated sensors and computer, to run at all.

the ea81 hitachi's are different than the ea82, though i dont know what years and what specifics other than the ea81's were slightly smaller cfm.

someone with more expierience with the feedbacks will chime in im sure.

the 2 screws are the ones your looking at. center is the air fuel and the one on the linkage is the idle. in general until your choke dissenges when the motor is warm the actual tuning cant be done. theres probably a 3rd screw which is your choke adjustment. on a more basic setup i would dissengage the vacuum to the choke while doing the actual adjustment, then hook it up and tune it after, but with the feedback I have no idea what it might be doing for the choke.


I swapped it out for an EA81 non-feedback. On the feedback there's a couple extra hose connections. It runs now but still with high idle. We disengaged the vacuum to the choke and blocked off the nipple on the intake, it just idles really high. The small screw at the bottom of the carb literally does nothing. You can turn it all the way in and drive it, drives ok except for it can pull itself right along cuz the idle is so high. Turn it all the way out, no difference. You can pull back on the linkage while the idle screw isn't touching, doesn't do anything. This is really weird.... it is driveable though, it'll get me the 60 miles back home I'm sure. After that... maybe Weber? Or SPFI.

#4 djellum

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Posted 14 November 2012 - 08:04 PM

check the butterfly valve in the bottom. it might be getting stuck or jammed and not closing all the way.

#5 ferox

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Posted 14 November 2012 - 08:26 PM

The small screw at the bottom of the carb literally does nothing. You can turn it all the way in and drive it, drives ok except for it can pull itself right along cuz the idle is so high. Turn it all the way out, no difference. You can pull back on the linkage while the idle screw isn't touching, doesn't do anything.

Somehow your idle circuit has been bypassed. It sounds to me like you have a major vacuum leak. The idle mixture screw should be around 2 turns out from lightly seated. Is the charcoal canister still hooked up or did you remove it? If you can post a picture of the carb and intake area that might help. You should really get this sorted out before driving it too much.

#6 Subaru_dude

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Posted 14 November 2012 - 09:14 PM

Somehow your idle circuit has been bypassed. It sounds to me like you have a major vacuum leak. The idle mixture screw should be around 2 turns out from lightly seated. Is the charcoal canister still hooked up or did you remove it? If you can post a picture of the carb and intake area that might help. You should really get this sorted out before driving it too much.


I totally think I have a vacuum leak somewhere, but for the life of me I can't find it. I've sprayed and sprayed and sprayed, and nothing. Yes the canister is gone. I'll try to get some pics tomorrow. I have to pull the motor Friday anyway because I used an Ea82 flywheel and can't set the timing. Had to go by ear...

#7 Subaru_dude

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Posted 16 November 2012 - 11:30 AM

So I drove it today, used alot of gas, and I noticed the engine was making boiling noises (assuming it's coolant), yet the temp gauge never really got above halfway. Is that possible? The guy who helped me said we didn't have to park it on a hill like an EA82 to get all the air out. Starting to think the dude was full of crap... He always told me touring wagons were longer than regular wagons (which is complete crap) and that the EA82 coupes had a longer front end than regular coupes. Is this guy delusional?

#8 Gloyale

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Posted 16 November 2012 - 11:38 AM

Feedback carbs used wide open air bleeds, with duty solenoids to restict them down for mixture adjusment. You've removed the duty solenoids....so now the slow air bleed has way to much air.


You need to restict the slow air bleed with an orifice.

Front of carb, smaller of the 2 elbowed ports on the top of carb.

I'd use a .5mm orifice to start, and get smaller from there if needed. But that is the size used in the Non-feedback setup.

#9 Gloyale

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Posted 16 November 2012 - 11:41 AM

So I drove it today, used alot of gas, and I noticed the engine was making boiling noises (assuming it's coolant), yet the temp gauge never really got above halfway. Is that possible? The guy who helped me said we didn't have to park it on a hill like an EA82 to get all the air out. Starting to think the dude was full of crap... He always told me touring wagons were longer than regular wagons (which is complete crap) and that the EA82 coupes had a longer front end than regular coupes. Is this guy delusional?


Park on a hill to get air out = True

Touring wagons longer = False, they are taller roofline...not longer.

EA82 coupe longer front end than regular coupe (ea81?) = true....if that's what he meant.

EA82 coupe windshield is raked steeper, and 1 inch longer.

#10 Subaru_dude

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Posted 16 November 2012 - 11:48 AM

Feedback carbs used wide open air bleeds, with duty solenoids to restict them down for mixture adjusment. You've removed the duty solenoids....so now the slow air bleed has way to much air.


You need to restict the slow air bleed with an orifice.

Front of carb, smaller of the 2 elbowed ports on the top of carb.

I'd use a .5mm orifice to start, and get smaller from there if needed. But that is the size used in the Non-feedback setup.


It now has a regular non-feedback EA81 carb on it.

Park on a hill to get air out = True

Touring wagons longer = False, they are taller roofline...not longer.

EA82 coupe longer front end than regular coupe (ea81?) = true....if that's what he meant.

EA82 coupe windshield is raked steeper, and 1 inch longer.


EA82 coupes have longer front ends than regular EA82 sedans and wagons. That's what he meant. He has a touring wagon and has always insisted it was longer which I always knew was crap. So I guess I need to go pull the car uphill and get the air out... like I thought to begin with but he insisted it wasn't necessary. :banghead: So you think it actually got hot?

#11 Gloyale

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Posted 16 November 2012 - 12:00 PM

It now has a regular non-feedback EA81 carb on it.


Still needs an orifice unless you installed the tubes and ACV (air control vavle) that where used in the OE setup.

#12 Subaru_dude

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Posted 16 November 2012 - 12:45 PM

I would post pics but I don't have my camera. I see 2 nipples sticking out the front of the carb that appear to be the same size when I pulled the caps off. According to GD you don't need the ACV anyway... And does the metal line from the passenger head to the intake need to be plugged off? It's still hooked up, but the big rubber hose coming off the side of the EGR is plugged.

Edited by Subaru_dude, 16 November 2012 - 03:25 PM.


#13 Ibreakstuff

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Posted 16 November 2012 - 01:20 PM

I know nothing about carbs but the "boiling" noise could just be air running thru your heater core. Mine does this if all the air isn't purged/burped out of them system.

#14 ferox

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Posted 16 November 2012 - 04:12 PM

Since you have had the same or similar results with two different carbs, the problem probably lies outside the carb itself. The carb may present problems also, but I would caution against tweeking it too much until you get the main initial problem figured out. Getting the timing dialed in will help. How is the brake pedal feel? Does it affect idle at all when it's depressed?

You don't need to do anything to the metal EGR tube, but I would recommend pulling the EGR and cleaning it of carbon deposits so it closes correctly and make sure it seals well when you re-install it.

#15 Subaru_dude

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Posted 16 November 2012 - 05:28 PM

Since you have had the same or similar results with two different carbs, the problem probably lies outside the carb itself. The carb may present problems also, but I would caution against tweeking it too much until you get the main initial problem figured out. Getting the timing dialed in will help. How is the brake pedal feel? Does it affect idle at all when it's depressed?

You don't need to do anything to the metal EGR tube, but I would recommend pulling the EGR and cleaning it of carbon deposits so it closes correctly and make sure it seals well when you re-install it.


Darn I was hoping that metal tube was my problem... it goes from the intake to that cylinder so I assumed it was acting as a vacuum leak. Thought since the big EGR tube was blocked off maybe somehow that was causing it to be a problem. Anyway, it's blocked off now and the tube is gone. I've sprayed all over the place with brake cleaner with no luck. I'm pulling the motor tomorrow to put the right flywheel on so I can properly time it. I don't think the timing is the cause of the stumbling because no matter how you adjust the disty it stumbles, even if it feels like it's in the right place. I've got the mixture screw turned out 3 turns. Seems that's a good place to leave it until I get this all figured out. If I can't get this straightened out I'm gonna have to get a job and ride my bike to work!!!

Also, we used Ultra Grey for the intake instead of intake gaskets. Is that ok? I've noticed it feels like one cylinder has liquid in it when cranking after it's been sitting overnight. If you start it after it's been ran it doesn't "chug" on any of the cylinders. Maybe coolant is leaking into the combustion chamber cuz the ultra grey ain't enough? Man I can't wait to SPFI this thing.

#16 Idasho

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Posted 16 November 2012 - 08:13 PM

Also, we used Ultra Grey for the intake instead of intake gaskets. Is that ok?


Uh, no.

:rolleyes:

#17 old sub freak

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Posted 17 November 2012 - 01:16 AM

Amen !!

#18 Subaru_dude

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Posted 17 November 2012 - 10:30 AM

Uh, no.

:rolleyes:



Thank you very much!!!!

#19 ivans imports

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Posted 17 November 2012 - 11:43 AM

have both ea81 and ea71 runing on ea82 carbs works realy good must be 85-87 non feedback carbs some addapting requred but works realy good my ea71 pu probly 25 % power and the ea81 about 20 % more butt the runability was way imporved

#20 Gloyale

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Posted 18 November 2012 - 07:03 PM

I would post pics but I don't have my camera. I see 2 nipples sticking out the front of the carb that appear to be the same size when I pulled the caps off. According to GD you don't need the ACV anyway...


ACV not needed, but without restriction the system is running really lean.

There are orrifices in there that meter down the air....the ACV used vacuum to open and close the passages for maximum efficeincy (i.e. ot leans out or close the Slow passage during Main operations/cruising)

But it's possible to leave the air bleeds open to atmosphere without the ACV, but it needs a bit of restriction to get the mixtures right.

My guess is your running really lean.

#21 Subaru_dude

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Posted 18 November 2012 - 08:37 PM

ACV not needed, but without restriction the system is running really lean.

There are orrifices in there that meter down the air....the ACV used vacuum to open and close the passages for maximum efficeincy (i.e. ot leans out or close the Slow passage during Main operations/cruising)

But it's possible to leave the air bleeds open to atmosphere without the ACV, but it needs a bit of restriction to get the mixtures right.

My guess is your running really lean.


So.... how do I fix that? Got any pics of a carb that has that done?? And running lean like it might be, should it still be using ALOT of gas? my GUESS is I'm getting mid teens. And should I be driving it like it is? I HAVE to drive it but I don't want to do any real damage... I haven't been driving much being that it smells so putrid it burns my throat and takes at least an hour for the burn to go away...

#22 djellum

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Posted 18 November 2012 - 09:54 PM

I run mine just plugged completely, though im running an EA82. mine runs a bit rich, but that is better than lean. still manage 28 mpg and runs pretty smooth. Heres the way I run it.

3 inlets from the firewall - fuel line like normal, fuel return like normal, tank vent line left open and unhooked.

air line in back of carb - plugged
both smaller air lines in top front of carb - plugged
vacuum line on baseplate - Plugged
vacuum line tucked in by throttle linkage - plugged
vacuum line on center front passenger side of carb - plugged
vacuum line on center front drivers side of carb - vacuum advance
bowl vent line - used a smaller diameter hose and left the hose a few feet long to help restrict the bowl vent just a little.

I dont run the canister or air box anymore, since im staging up for a weber.

imo the only real important thing to check other than vacuum leaks is the bowl vent. it has to be at least in the ballpark or it just wont run right. best option is orificing them all, but if the bowl vent is right you can plug the rest of them without too much worry.

you will get bad gas mileage either way you go, rich or lean. proper mixture means clean efficient and powerfull. anytime its off it means more pedal and less efficiency. the problem with lean is combustion temperature and spark knock. if its making a lot of noise under load I would probably not drive it much. if the engine is pretty fresh its not going to kill it immediately, but if something in the motor is worn or weak it might hurt it.

the only pics I have are off of an EA82, which should be similar but the direction of things are sometimes reversed. dont want to confuse it more.

#23 Subaru_dude

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Posted 18 November 2012 - 10:46 PM

Well hell I heard knocking earlier, definitely must have been spark knock. I can't hear much from the engine because the exhaust is pretty loud. I'm just going to spfi, from the sounds of it I have the carb set up like yours... I'm definitely NOT wanting to hurt this engine. It needs to last me a while.

#24 djellum

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Posted 18 November 2012 - 11:06 PM

dont automatically assume its the carb.

Id change those intake gaskets before doing anything else.

diagnose the problem and fix, throwing on another system will just make it harder to diagnose later. vacuum gauge, fuel pressure, timing, spark, etc. whatever it takes to narrow down the problem before you swap in.

#25 Subaru_dude

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Posted 20 November 2012 - 12:48 PM

Id change those intake gaskets before doing anything else.


After removing the intake, I'm pretty darn sure using Ultra Grey for intake gaskets isn't worth a crap. As soon as I can get a ride the 40 miles to the nearest Subaru dealership, I'm getting proper equipment.




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