hitachi float adjust?

[sdsurf]

Just threw on an old Hitachi and the truck is running good, however, the idle is high. The entire float bowl is full of gas. How do I adjust this? could it be a needle valve issue? I don't really want to do a complete rebuild yet as I am moving in the next two weeks...

[ggzilla]

The fuel should come up highway in the sight-glass.

 

No need to rebuild it. Just adjust the float valve. Remove the top and bend the tab.

 

after adjusting the float level, you will need to adjust idle speed and idle mixture. Float level is the primary adjustment, and has to be done first.

[datzenmike]

Pinch the rubber fuel line and run it out of gas or pack some rags under the front to catch the gas, and remove the three screws from the front cover glass and pop it off. Save the rubber 'O' ring. If dirty clean with gas and dry it. Take note that if you remove the brass float that there is a tiny brass spacer on the pivot point between it and the glass that will fall out and be lost. Carefully remove it first, then slide the float out.

 

The top of the float has a 'tang' or arm that bares against the float to push up and close it. With the float removed, carefully bend it open slightly and install. Gently lift the float with a finger or pencil until the needle valve is closed and there is slight resistance. The space between the top flat surface of the float and the underside flat surface of the float chamber should measure 0.28" (roughly 1/3 of an inch) I just adjust until the top of the float is parallel with the top underside of the float chamber. This should bring the fuel level down to the 'running' range on the sight glass.

 

Remember very small adjustments make big changes. Needle nose pliers are handy for bending the adjustment tang. You may have to gently push the needle valve up slightly to clear the tang when sliding the float back on to the pivot. Clean the gasket 'O' ring surfaces with an old toothbrush so that it seals. Always check for gas leaks. Oh, don't forget that small brass spacer.

Edited December 26, 2009 by datzenmike

[DanielC]

Sometimes a small piece of dirt will get caught between the needle ans the seat of the float valve. Occasionally, it can be removed by letting the carb gas level run down, and than the seat opens enough to flush the piece of dirt out of the valve.

[ggzilla]

Ah even easier than I thought. This is the Hitachi DCH340 right?

[datzenmike]

Ahhh I was wondering about the 'remove top' part.

[sdsurf]

The earlier one. I think it is the 326.

 

Thanks for the help Mike! I will try it out tomorrow!!

Ah even easier than I thought. This is the Hitachi DCH340 right?

[rbastedo]

The earlier one. I think it is the 326.

 

Thanks for the help Mike! I will try it out tomorrow!!

 

I am having some similar trouble with my Hitachi downdraft carb.

I'll try the 'run it out of gas' trick later today, but the issues it is having might not be that.

It will no longer idle smoothly, it wants to climb up in rpm or drop off and die especially when I come to a stop like at an intersection.

One thing to add is that the adjuster that is on the back side where that vacuum thing connects with a little arm seems to have almost fallen off.

I reattached it but still can't get it to idle correctly. I have the mixture set rich and the idle turned up just to keep it running most of the time.

Ideas?

[datzenmike]

Check the sight glass level or the 'bull's eye' level on later Hitachis. If the fuel level is close leave it.

 

As to poor idle and problems. Be sure your ignition system is in good shape, correct timing set and your valves adjusted to the proper clearance first.

 

Check the mounting bolts are tight on carb to manifold and manifold to head. Spray some WD-40 around the base... if there is an idle change you may have a leaky gasket.

 

Check/replace any broken or missing vacuum hoses.

 

Is the choke plate closed when starting the motor cold and opening when the motor warms up?

 

Is the idle cut solenoid working? Have someone turn key ON/OFF/ON/OFF and listen for a click sound at back of carb. Clicking is good.

[rbastedo]

Fuel is about halfway up in the window.

 

Ignition recently gone through, it was running great for over a month after that.

I will check for vac leaks, early on when I got the car it had very loose mounting that I found when I grabbed the carb and found I could rock it forward.

After that I took it off and made sure the gaskets were good and reinstalled it good and tight. Ran good for a long time after that.

I'll still do the WD-40 spray to make sure and of course looking for bad hoses.

I installed a manual choke over a year ago, and it's still operating correctly.

The idle cut off was a problem a couple months ago, I found the red wire broken and repaired it. That's actually working correctly.

 

Thanks!

 

 

Check the sight glass level or the 'bull's eye' level on later Hitachis. If the fuel level is close leave it.

 

As to poor idle and problems. Be sure your ignition system is in good shape, correct timing set and your valves adjusted to the proper clearance first.

 

Check the mounting bolts are tight on carb to manifold and manifold to head. Spray some WD-40 around the base... if there is an idle change you may have a leaky gasket.

 

Check/replace any broken or missing vacuum hoses.

 

Is the choke plate closed when starting the motor cold and opening when the motor warms up?

 

Is the idle cut solenoid working? Have someone turn key ON/OFF/ON/OFF and listen for a click sound at back of carb. Clicking is good.

[Grey_Matter]

where is the float level supposed to be on the earlier carbs? there are no reference marks on mine that i can see.

 

i took the truck on the freeway for the first time today and it seems to be flooding out while cruising. my float bowl sight glass is about 3/4 full. im pretty sure this is my problem.

stop and go drivinf it does great, but if i have to maintain a speed (say 45mph) it will start to choke out and die. it starts back up as long as i dont touch the gas pedal and idles fine, i have to feather the throttle to get it running right again, then its fine until i do a long stretch again

[datzenmike]

The newer carbs had a solid metal cover on the front with a small round 'bull's eye' (glass with dot in the center) the older ones had a full glass front on them with an etched horizontal line for the fuel level. As long as it's close it will work.

 

Next time you are out on the highway and it starts to act up, as quickly as possible shut off the motor and slip into neutral. You are trying to stop the motor as fast as possible. Do this away from other traffic where it is safe to do so and pull over to the side of the road. Lift the air filter off and look at the level of fuel in the bowl. I'm betting that it will be low or empty. If so replace the fuel filter.

[Grey_Matter]

The newer carbs had a solid metal cover on the front with a small round 'bull's eye' (glass with dot in the center) the older ones had a full glass front on them with an etched horizontal line for the fuel level. As long as it's close it will work.

 

Next time you are out on the highway and it starts to act up, as quickly as possible shut off the motor and slip into neutral. You are trying to stop the motor as fast as possible. Do this away from other traffic where it is safe to do so and pull over to the side of the road. Lift the air filter off and look at the level of fuel in the bowl. I'm betting that it will be low or empty. If so replace the fuel filter.

 

like i said...there is no visible line or reference mark on my sight glass.

 

but i will try replacing the filter...i shoulda did that a long time ago when i was first having the carb issues

[datzenmike]

Looks fine for level maybe 2/3s way up.

[Grey_Matter]

Looks fine for level maybe 2/3s way up.

 

that not where it usually sits. thats after sitting overnight, when its running its usually 3/4 full

i am picking up a fuel filter on the way to work today for sure

[Grey_Matter]

The newer carbs had a solid metal cover on the front with a small round 'bull's eye' (glass with dot in the center) the older ones had a full glass front on them with an etched horizontal line for the fuel level. As long as it's close it will work.

 

Next time you are out on the highway and it starts to act up, as quickly as possible shut off the motor and slip into neutral. You are trying to stop the motor as fast as possible. Do this away from other traffic where it is safe to do so and pull over to the side of the road. Lift the air filter off and look at the level of fuel in the bowl. I'm betting that it will be low or empty. If so replace the fuel filter.

 

filter is replaced and it didnt make any difference...its still doing the exact same thing. i did pull over and check the float bowl, it wasn't empty, but it was only about a 1/4 full which is far lower than it usually is (usually about 2/3 to 3/4 full)

[dat521gatherer]

LOOK CLOSELY I CAN SEE THE ETCH LINE ON THE GLASS.

[jalexquijano]

Does the float tang on the 3 screws su carbs touches or presses the needle valve pin? I am still confused how to obtain the precise .55 inch gap on both floats. Nobody seems to clear this out! Ztherapy Just SU DVD dealt with Grose jets and not needle and valve!