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well, i thought i'd seen the last of these Murphy carbs a few years ago but alas....

the problem here is a typical hitachi thing, but due to my inexperience with these things i have to ask.

the thing runs fine most of the time. until i take it out bashing. then it refuses to idle. (unless the choke is on ) after it warms up no idle again.after a few days things go back to normal. i originally though this was a plugged idle jet, but after pulling the carb apart i can find no grit or buildup anywhere. the moron who owned the truck before me used 3 ft of copper fuel line (replaced) i have three filters on the line now ,one before the pump one after the pump (pulled the in pump filter)and one just before the carb. tank was flushed out and coated after i bought it.

this time i didn't go bashing. it just stopped idling about a mile down the road from home. there's no linkage issues, or vac leaks. and the idle solinoid is working correctly. on the whole this carb ran a little rich for 6000 ft, but very well.

yes, i've already though about the weber and i'd like the truck to be smoggable, so i won't be going that direction.

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I have a 79 pure stock with hitachie carb, mine was doing a kinds of strange things also, I pulled it off and cleaned it twice. all new vacuum lines and it has been behaving lately runns a little stronger in cold weather but I'm at 5700 feet elev. and I think it's due to thicker air.

I had the same problem and found that the wieght that holds down a check ball was sticking , it stops the primary circuit working , let it sit and next day it works fine till it sticks , engine hard to start and runs only if at high rpm.s [thats when 2ndary curcuit comes in ] THE CURE is remove brass wieght ,polish it severely , use Q tip and dremel with polishing compound to smooth out the hole it fits in and no more sticking . hope this helps Jim P. S. it also helps if you smooth any other surfaces that rub or slide

ok..... i really think the moron who rebuilt this carb before me is a complete and total tit.

i'm of the opinion that he removed the venturi's and re installed them in the wrong bores. the smaller one(id with two ugly bumps) is on the secondary side and vice/versa. i hadn't noticed this before because YOUR NOT SUPPOSED TO REMOVE VENTURIS WHEN YOU REBUILD THE CARB!

does anybody have a hitachi that can look down the throat and tell me which one goes where? or post a pic of the top with the choke open all the way? it looks like the smaller one goes in the primary side in all the diagrams i've seen but that's a diagram not a photo of an actual working carb.

on a side note, the original problem that started this post is fixed, turns out i had knocked a little bit of brass off the jet and it was moving back and forth in the carb intermittently plugging the primary slow jet.

i do believe i'll be able to do a write up on properly rebuilding this carb by the time i'm finished.

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Hey Wook I'll take a gander tomorrow and let you know which is which.

OK wook I looked at my hitachie carb circa 1979. They both look the same to me the only difference I could see is the secondary side has a 9 on it. I hope this helps