i have a 1985 subaru brat and although i am not new to subaru's i am new to the older ones. my brat has the hitachi carb and although it runs relatively well when warm, the choke sticks when cold and it has a very bad hesitation when beginning to accelerate and is running very rich and i have no idea why or what to do so i am in the process of purchasing a weber kit  however i live in vernal ut and the elevation is around 5,800-6000 feet and when i travel up the mountain for camping hiking etc. i will be around 9000 feet. i was wondering if anyone has experience with webers at this elevation and could give me a good base for jetting. i am very new to carburetors and dont really know how to tune them. any help would be appreciated. 

The Hitachi issues could be due to clogged emulsion tubes or a float adjustment. Look at the little sight glass and see if the fuel level while idling is at the middle. If it is above the middle... adjust your float. Hitachi are carburetor hell though, so if you're new to carbs, I would not start by taking apart a Hitachi. From my understanding, the Webers base jets (PRI 140 and SEC 140) are extremely multipurpose... there are plenty of old threads that could be of help to you I'm sure. try using the search function in the top right of the page

 

Welcome to the USMB by the way!

I'll get the numbers for the jets, from Bow Wow, very easy to change and will run great, might have to get 6 of them tho, just saying

Cause six ajustments for those, want to lean the f out of it for those altitudes

Edited December 11, 20169 yr by machineit

The fuel level in my hitachi is perfect and i dont know what an emulsion tube is haha. My weber was supposed to be here friday but is stick in salt lake city at ups for some unknown reason and they cannot update me on eta at this time so now i wait. The distributor i got the carb from said to increase the air meetering jet size up one size to start. But i thought jetting the fuel jets down would be better.

Edited December 11, 20169 yr by gtmst3

Redline sells a high elevation jet kit.  They come with everything you will need.  The air adjuster jets are probably what you are going to need to adjust.  I did this too my toyota 4x4, it was fairly easy, but you just gotta' play with it.  Get the primary set perfect before you tare into the secondary.  Once you change something you will get the idea.  If you got hesitation it is probably running lean, assuming you don't have other fuel delivery issues.  Fat and happy, I think the saying goes.    webers like fuel, so going down a jet might not work out all that well.

Edited December 11, 20169 yr by Schnayke

I am having the worst time tuning this carb. Got it running really smooth by upping the ait correction jet from 170 primary to 190 with a 140 main jet but i feel like there was a loss on power. I have had the carb apart about 7 times before getting it this close but you can deffinatly tell its not right this is very frustrating, also i only get about 1 to 1.5 psi of fuel pressure at the carb, new fuel filters and new o.e. replacment fuel pump. I dont think this is causing any problems but i guess it may. I think my jetting is just off still.

Mine won't run right unless I have at least 2 psi, Weber's are going to want like 2.5 or 3, for off road use, and a bit higher on off road use.  Looks like max pressure for stock pumps are around 2 psi for your engine.  It can be a bit frustrating at first, but you will figure it out.   Have you adjusted the secondary yet?  Have you checked the float specifications?  You may need to adjust it.  Have you tried adding a bigger primary jet?  Always right down your figures as you go so you can look at your notes to help figure it out.  Are you getting hesitation, when you step on it?

Did you use a vacuum gauge to get your baseline tune correct? Search YouTube for how to tune a Weber. See if you can get anything from that

Edited December 19, 20169 yr by Sapper 157

https://www.youtube.com/watch?v=zGDp3wKj8o0  This video kinda' breaks it down a bit for ya.

Edited December 19, 20169 yr by Schnayke

i have adjusted the secondary and its operating relatively well i did have to adjust my float slightly, this morning  i wend back down to a 135 main jet and a 180 air correction jet, exactly the same performance as when i has a 145 main jet and a 190 air correction jet, so i think now i either need to go one up , one down or stay the same for a main jet and it will be about as good as it will get. its running very smoothly it just feels like its lacking in power.  

Maybe timing?  I have always had to run more advance on webers over stock carbs, However I have only ever installed them on nissan, toyota, and fords.  However they all where basically the same kind of setup.