mkc1962 Posted July 12, 2015 Share Posted July 12, 2015 Can any of the serious carb gurus out there provide some feedback on the difference between a Std Carburetor, and the one that was modified for HIgh altitude? Thinking it is no doubt something in the jetting, probably smaller main jets and if so what are the std jet sizes vs the HA sizes. If in fact the HA are just smaller, drilling to enlarge would not be a big obtacle. I recenty aquired an 82 Brat that very clearly lableled has the HA model carb on it. I'm not against maybe rebullding it to have as a spare, but with the HA modification need to undestand exactly what that is to make it compatible for my environment. Thanks for any feedback. Quote Link to comment Share on other sites More sharing options...
ccrinc Posted July 12, 2015 Share Posted July 12, 2015 Carburetor is a French word meaning "Leave it alone". (Sorry. I couldn't resist) 1 Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 12, 2015 Share Posted July 12, 2015 (edited) The purpose of the kit was probably not performance but rather emissions. Its installation would have some effect on drive-ability. I actually think the HA kit consisted of only external mods. Perhapse, timing was readjusted and some vacuum lines were rerouted and/or installed with different size orifices that ran to the carb air bleeds. I have some info in the posted thread on these passages. http://www.ultimatesubaru.org/forum/topic/154295-just-plug-it-taking-some-of-the-mystery-out-of-your-hitachi/ Of corse I could be wrong. And it may not matter because you may have a feedback carburetor, in that case the ECM is set in high alt mode and there are additional gizmos involved. Again tho i think the carb internals remained untouched. If it is a feedback unit you wont be saving it. http://www.ebay.com/itm/SUBARU-HI-ALTITUDE-KIT-3D-4D-WAGON-4WD-/261147931818 Edited July 12, 2015 by ihscout54 Quote Link to comment Share on other sites More sharing options...
ccrinc Posted July 12, 2015 Share Posted July 12, 2015 Anybody who lives in Colorado, and who has owned a carbureted car knows that one had to have the carb adjusted for high altitude. My first one here wouldn't go over 10K ft even though I had it done for "mile high". It's more of a "less gas, more air" thing. Today's EFI systems don't need mechanical fixes: they're all controlled by computers. An '82 Brat had no ECU or any other kind of computer. Is it a Weber or Hitachi? http://www.autozone.com/repairguides/Subaru-ff-1-1300-1400-1600-1800-Brat-1970-1984-Repair-Guide/Carbureted-Fuel-System/Carburetor/_/P-0900c15280065ae8 Quote Link to comment Share on other sites More sharing options...
mkc1962 Posted July 12, 2015 Author Share Posted July 12, 2015 (edited) Carburetor is a French word meaning "Leave it alone". (Sorry. I couldn't resist) ..well...seeing as I how I build dozens of carbs annually.....its just not in my nature to leave them alone that and it wont stay running for long....if its coming off I'm gonna ultrasonic clean, bead blast and rebuild. Do it right or not at all. Thanks for the feedback guys... and will research those links. So far from what I am seeing based on the HA decals and the tubing, its got several factory vacuum mods. Without removal no idea of the internals. This carb that is on it definately does not have any sort of feedback circuit. the only electrical devices on it is a fuel cut valve and a idle up. As I jsut got the thing and havent done much to it, I assumed it to be a hitachi. However after just going out and looking it over real good was only able to find one set of cast marking, that being MADE IN USA. that tells me its more than likely Carter Weber, as to my knowledge none of the Hitachis back then were ever made in USA. Regardless which it may be, the HA modifications are what I'm interested in. I have the kits on hand to rebuild either of the makes. Edited July 12, 2015 by mkc1962 Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 12, 2015 Share Posted July 12, 2015 (edited) Anybody who lives in Colorado, and who has owned a carbureted car knows that one had to have the carb adjusted for high altitude. My first one here wouldn't go over 10K ft even though I had it done for "mile high". It's more of a "less gas, more air" thing. Today's EFI systems don't need mechanical fixes: they're all controlled by computers. An '82 Brat had no ECU or any other kind of computer. I sorta doubt he has the Carter/Weber and if he did it would (in stock form) have very likely been a feedback. Feedback models are computer controlled. You bring up a good point. The high altitude kits would seem a rareish afterthought. A market requiring these kits be installed from day one would have been small. Seriously other than some places in Wyoming, New Mexico, Colorado, Arizona etc. not many cars would have had these installed. Most cars of the area would have struggled at 10k. Even with this kit installed as you said it still wouldnt go over 10k. In your state Ide bet the majority of the cars were fitted with these kits, since your biggest city is over 5k ft. My region varies from 3000-7800ft quickly. In the 80s I doubt there was a Subaru dealer in the area (a new car would come from Phoenix) and not have such a kit installed. Even if they were sold in Flagstaff it was a different era, there was no internet. Just phone books and rotary phones. People had to commute to the valley for work, or drive all over to find a vacuum bag because Sears Roebuck of Prescott did not service Fingerhutt vacuums. For this reason areas like mine probably did not get the kit. Im so glad we have the tech we have. Unfortuneately I wasite way to much time typing pointless essays. Guess its time to get busy actually doing stuff! Edited July 12, 2015 by ihscout54 1 Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 12, 2015 Share Posted July 12, 2015 This carb that is on it definately does not have any sort of feedback circuit. the only electrical devices on it is a fuel cut valve and a idle up. This does sound more like the 1bbl Carter the Hitachi is 2bbl. There is more wiring here you didnt notice, choke element is one you missed. Its also totally possible the engine or fuel system is not original. The "fuel cut valve" you mention could easily be the feedback metering solenoid on the Carter carb. The idle up is more likely the idle stop solenoid on the Carter. No matter, if you do have the Carter my opinion is: time to start looking for another fuel system including the manifold and carb itself. Parts for these are expensive and rare. Carter Hitachi Thank you nationalcarburetors.com Quote Link to comment Share on other sites More sharing options...
mkc1962 Posted July 13, 2015 Author Share Posted July 13, 2015 IH, thanks for the continued feedback. I'll know more exacts when I actually start working on the thing. Right now I have 2 cars in front of this one (paying customers) This brat is my personal toy. I have all the original papers, this Brat was bought and spent most of its time in the Denver and Golden Colorado areas, probably why the HA might have been on it. Based on a FSM that I have, it clearly shows that feedback carbs and simple ECM's were on some 82's. I havent looked for an 02 sensor yet, but if its got one, that clearly shows that signal is used to manipulate running mixture or why would it have one? However, based on your pictures (thanks you by the way) it clearly appears that I have the 1bl Carter/weber. Its been about 15 years since Ive built one of those but do still have a few kits and misc part about for it. Your correct about more wires, I was referrring to wires that actually aid in runing the thing vs a choke wire used solely for starting. True if the solenoid control valves go out they are getting pretty hard to find, but Ive rewound a many of them its just very time consuming and tedious but cheap. Now that I look at it in more detail, I clearly see the FSM almost identical to MCS (mixture control solenoids) On higher end Hitachi carbs. Yes those are getting hard to obtain as well but not impossible. IF in fact the simple ecm is the issue, very correct probably time to scrap. I'd like to keep it stock if its possible and within reason, but I also have another carb and intake deal in place just in case. Nice to know that the newer Weber is also an option with the right intake. 1 Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 13, 2015 Share Posted July 13, 2015 Look under the dash directly beneath the steering column or actually bolted to it. If there is an ECM thats where it would be. Just becuae its not there doesnt mean the carb is non feedback. Just may mean the system is incomplete/inoperative. The car will run without this but will be very rich. If its from colorado I dont see it being a feedback 4wd but again who knows whats been done over the years. My opionions only and as they say "worth the price charged" keep us posted. Quote Link to comment Share on other sites More sharing options...
mkc1962 Posted July 13, 2015 Author Share Posted July 13, 2015 I'll give it a looking over today after a few hours sleep. OH yeah, Ive dealt with incomplete stuff quite often. The truck appears quite stock and for the most part unmolested. The young man I got it from had just drive it to Alabama from new mexico. I think he had gotten it from original owner and says it was running fine until he moved to this region. Couldnt find anyone to work on it. I think the region thing HA vs LA was just coincidental. Usually they still run regarldess of altitude just poorly. This one your lucky if it starts at all, and if it does will idle fine but stumbles when given power....Carb looks all original and untouched, but you never know its 33 years old. Quote Link to comment Share on other sites More sharing options...
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