Dltx 71 on a B?

jwitty

Member
So I took off the carb again on my john deere b because it's still running rich. Think I found out why...its got a 71 one it and I believe it should have a 67 or 73. So...what can I do here? Is it possible to run it still on this? Would someone in Iowa happen to have a 67 that they would trade me maybe?
 
I rebuild these and my own '50 "B" has a 71 on it and does all functions perfectly. I do have the intake manifold tapered to fit the 71 size. The carb size only sets the amount of air it allows to engine . The fuel to air ratio is fully adjustable with the needles...which , by the way, are the exact ones the 67 uses. Passages are all the same size also. It is NOT your "running rich" problem.
 
(quoted from post at 19:52:02 11/20/17) I rebuild these and my own '50 "B" has a 71 on it and does all functions perfectly. I do have the intake manifold tapered to fit the 71 size. The carb size only sets the amount of air it allows to engine . The fuel to air ratio is fully adjustable with the needles...which , by the way, are the exact ones the 67 uses. Passages are all the same size also. It is NOT your "running rich" problem.

Well I ripped out the baffles and cleaned the venting passage and cleaned everything. Is it ok to run it without the baffles in? Or will like fuel spill all over?
 
What does it do if you throttle it half way open and close the load needle shut? That will stop the load circuit from even entering into it. They run from idle to wide open throttle on just the idle circuit. They do need the load open some to accelerate from idle up to WOT but once up there shut the load tight. Your idle should be open 2 turns to do this. Now slowly turn idle in until engine dies and then back out 1/4 turn. Your idle is now set. If this worked then it means the load circuit is getting too much fuel into it. You should be able, now, to open load up one turn and re-start tractor and it should do everything right. If it now floods again, turn load in slowly until it evens out. Doesn't matter what the manual says on these old things. lot could have happened since new. I just did one (67) doing same thing as yours. Turns out, someone did a stem thread repair on it. It was broken way above the shoulder and had the threads and a large "collar" even above that yet. That means they had to drill a new load needle hole/seat. They drilled it too large. Very little movement on load needle now to make huge difference in fuel. This carb runs perfect now BUT with only 1/2 turn open on load screw. Some "hot rodder" tractor puller probably figures this is how you get more HP. Check to see if yours has had new threads welded on and/or any cracks in the casting on the stem where un-metered fuel might get in. One thing is for certain , tho, It is not the fact that it is a 71 doing it.
 

Wow, so the only thing I changed was I took out the baffles and cleaned the passage and now it's running a LOT better. So I think I'll just get a hardware and gasket kit for it and it should be all good!
 
Whenn that passage is plugged, it forces fuel entering the bowl to push through the load needle orifice and into nozzle and out vent hole in front of carb throat. It will keep running out there instead of filling the bowl because it can't fill bowl against air pressure. If they are plugged bad enough, it will run fuel right out the front of carb. Glad you found it.
 

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