So I've got a hitachi carb on my ea81 so my carb or engine not sure let's off a lot of white in the morning when I'm first starting her up. Also once the engine is warmed up it'll do this jerking thing when I hover like the carburetor is choking itself that really slams my transmission and engine which really scares me as I'm currently in a battle of getting the old transmission mounts off to replace them(bolt is In there good). My buddy says it's the lack of back flow I have due to not having a full muffler. Just cat and exhaust. Any thoughts?

I have the same issue 

 

http://www.ultimatesubaru.org/forum/topic/141160-hitachi-carb-issues-after-partial-rebuild/

So I've got a hitachi carb on my ea81 so my carb or engine not sure let's off a lot of white in the morning when I'm first starting her up. Also once the engine is warmed up it'll do this jerking thing when I hover like the carburetor is choking itself that really slams my transmission and engine which really scares me as I'm currently in a battle of getting the old transmission mounts off to replace them(bolt is In there good). My buddy says it's the lack of back flow I have due to not having a full muffler. Just cat and exhaust. Any thoughts?

 

The smoke at start up is usually old intake valve seals.  Once they get old they allow oil to seep into the cylinder when the engine sits for a while and it burns off at start up.  

 

The jerking once the engine is warm could be a lot of things.  I am not quite sure what you mean by hover, but whenever I have experienced jerky behavior from the engine it was usually because the fuel filter was clogged.  That's definitely something that needs to be changed on a fairly regular basis on a carbed ea81.  The fuel pump only puts out 3-5 psi on average, so it doesn't take much to restrict fuel delivery.  My wife's old '84 wagon had a rusty gas tank and that used to happen all the time.  That's probably the first place to check, and if the car is new to you, then it's something that should be replaced anyway.

 

The ea81 can be sensitive to exhaust leaks, but probably not from lack of a muffler.  If you had a leaky exhaust gasket or some other leak closer to the head then you will definitely experience poor performance, but lack of a muffler probably wouldn't have such a pronounced effect.  I believe the back pressure/exhaust velocity mostly comes from the diameter of the exhaust system itself. 

Edited September 27, 201312 yr by ferox

I love my TBI ea81 try the inlet screen on carb inlet line bad for pluging up

I wish my car would hover -might get better mileage!

Just found this post again. I know I ran my car with...Bad gas.... New to carbs... Pretty sure I screwed up. I'll check out the fuel filter in the morning and order a new gas tank sometime and let it sit in my garage for a few weeks before getting it into the subaru