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| DCH-306 Carburetor |
Subject: DCH-306 Carburetor
by windmilldave on 2014/1/11 18:32:10
History: 30 years ago I bought a 72' Datsun B110 car from a junk yard to use for parts to fix another car. Then I scrapped everything except the engine, 4 speed stick trans., propeller shaft and rear end. Then in 1993 I went into the windmill business and needed a boom truck to take down and erect windmills. I bought an old 1967 International 2 ton truck and built a 36' boom and mounted on the truck chassis. I decided to use a small engine, instead of the PTO off the trunk tranny, to run an 8000 lb. winch and also have it drive a 2 gpm hydraulic pump to raise the boom and for outriggers. So I mounted the 1200 cc engine with 4 spd tranny, shortened the drive shaft to adapt to the pinion shaft, which I removed from the rear end and mounted that to drive the winch. I took a small radiator from an Opal car and mounted it sideways so that I could mount the hydraulic pump right off the front crankshaft pulley. I put in a new carburetor kit, plugs, points and condenser. The engine shares the truck gas tank and battery. It fired right off and ran good. The engine only runs at idle or fast idle most of the time when in use except at times if I'm pulling pipe out of the well I run it half throttle. About 6 yrs. later the engine wouldn't idle very well, even after adj. the idle adj. screw. Went to put in another carb kit and noticed the bowl cover gasket wasn't indented equally on all sealing surfaces. Took a flat file and smoothed up the surfaces both upper and lower bowl assy. Installed new carb kit and ran fine. About 6 yrs later had to repeat the process again.
New problem: Now several weeks ago it won't run at all even with choke fully closed except unloaded, unless I hold my fingers over the carb opening and allow only a very small amount of air to create more vacuum. To get enough gas to start requires several pumps with accelerator pump and at least 1/3 throttle and fingers over the opening. Manifold vacuum is around 20". Used carb cleaner all around manifold to head gasket. Plus all around carb gaskets with no increase in speed. Squirting carb cleaner into intake increases engine speed but then back to barely running. Seems to me there is not enough vacuum in the venturi to pull the gas through the emulsion tubes. I wasn't able to remove the tubes for inspection and cleaning. Gas in sight bowl is right on the dot. The engine never has to reach full power so the power valve and secondary's are never engaged. I have a mechanic friend who has done quite a few carburetors and put it back together and he didn't find anything wrong either. Is there a way to remove the emulsion tubes?
Dave..
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