1951 John Deere B with a jd 50 power block

[Daveb50]

Looking for any help that may be out there. We put a jd 50 power block into our b this summer. Now we are trying to get the bugs worked out. We have an issue with it cutting out. The governer asks for more fuel and the tractor falls on its face. Tryed adjusting the linkages and nothing seems to help. Last night I removed the linkage from the side of carb. Started the tractor and by hand opened up the butterfly on the carb. Didn't even reach half way open and it fell off. Any idea?

 

[buickanddeere]

Leaning out due to extra airflow.

 

[Daveb50]

So you think it has to much air? The spark plugs are black sewty looking

 

[MIKE R]

So you think it has to much air? The spark plugs are black sewty looking

Defiatly not the correct mixture. They should be a beigh color. The black junk on the plug is reffered to as a fowled plug.

 

[Daveb50]

Ok thank you. I know it has two screws on each side of the double barrel carb. So I will try to get the mixture right. Thanks again

 

[MIKE R]

Ok thank you. I know it has two screws on each side of the double barrel carb. So I will try to get the mixture right. Thanks again

Do you have a manual with the initial adjustments on the carb?

 

[Daveb50]

Well it's a jd 60 carb. I believe the manual says 1 1/4 turns for a 50 and 2 1/2 turns for a 60

 

[Daveb50]

But in my thinking I believe that it should be less than 1 1/4 turn. Because the carb is jetted for a 60. The reason we are using this carb is we were told we needed it for more fuel for the power block. Any ideas?

 

[MIKE R]

But in my thinking I believe that it should be less than 1 1/4 turn. Because the carb is jetted for a 60. The reason we are using this carb is we were told we needed it for more fuel for the power block. Any ideas?

With the carb for the 60 it will be jetted bigger. This is allowing the fuel that would go into the bigger engine on the 60 to go into the one on the 50 flooding it and causing your problem. With the carb set properly it will work. If it idles fine to about 1/4 throttle then dies when revved higher it is most likely the main jet that is plugged. Also check your choke that is is not disconnected leaving the buttery valve to float freely.

 

[Soundguy]

i agree with mike r.. especially after hearing about the plugs.

 

[Daveb50]

Alright tryed adjusting the carb. Still ran the same. But noticed that you are correct about the 1/4 throttle shut down. So that will be next. Check the main jet. Now this carb came came off a running 60 but I guess we coulda sucked something up. Thank you for your inputs. It's greatly appreciated!

 

[MIKE R]

Alright tryed adjusting the carb. Still ran the same. But noticed that you are correct about the 1/4 throttle shut down. So that will be next. Check the main jet. Now this carb came came off a running 60 but I guess we coulda sucked something up. Thank you for your inputs. It's greatly appreciated!

Is there any crud in the tank that could have found it"s way into the jet.

 

[buickanddeere]

So you think it has to much air? The spark plugs are black sewty looking

That makes a difference. You didn't mention sooty plugs initially.
Running 3116 autolites and solid core wires? Coolant temps 180-195F. The only problem could be shorting out plugs due to fouling , caused by incomplete combustion.
What fuel octane and timing to compensate for the power-bloc's much higher compression.

 

[Daveb50]

We are jus running regular fuel 87 octane and ignition timing has been moved forward and back and there's no difference

 

[Daveb50]

The tank was completely cleaned out

 

[Soundguy]

you need to trace the problems and work on them.

black sooty plugs will either be too much fuel, or incomplete combustion from weak spark... or a vacume leak causing you to need too much choke or extra fuel to keep the mix rich enough to run. I could see a flood condition causing this, and make her fall on her face when given the order for more butterfly from the gov..

 

[Daveb50]

Ok so not sure how I'm not tracing or working on them. So tonight we will start with a hotter champion b23 plug with our fuel air mixture set at 1 1/4 turns and see how it works. Last night we had it back firing thru the carb. She runs at idle jus fine until you give the butterfly a turn near 1/4 throttle and then she falls off and the plug near the fly wheel is really bad soot and the other is black but not as bad

 

[Soundguy]

just for kicks.. have you comp tested her?

bad valves COULD possibly cause some of this...

 

[Daveb50]

What's comp ratio of a 50 power block? And has all new valves and springs in it

 

[Daveb50]

And we had the valve cover off last night and checked the rocker arms for the required gap and it checked out fine.