carburator

abcd · Post by **abcd** » Wed Feb 01, 2006 11:51 am

I have a 74 john deere 300, i have a new carb kit and all new fuel line put on also a new filter. I got it running but when it runs it won't sit thier and idel for me. Thier are 3 screws one is round and the other 2 have springs in behind them, i don't know which screws to turn to make it idel.

JDXsand00s · Post by **JDXsand00s** » Wed Feb 01, 2006 12:01 pm

i'm assuming it is a walbro, so the screw without the spring, it should be on the right side of the carb. the top needle ajusts fuel/air and the one on the left ajdust's idle mixture.

ProJd69 · Post by **ProJd69** » Thu Feb 02, 2006 4:22 am

Just thaught I would throw this in, You should have the Walbro WDA31 carb. on your '74 300. Now when you look at it (like sitting on your sled) you have a screw w/ 2 nubs sticking out (so you can turn it with your fingers) and a slot for a screw driver on the left with the letter "L" stamped on the carb. next to it. You should have another that looks the same sticking out the top w/no letter stamp on the carb. and another that looks like a regular screw (may change model to model) but it wont have the nubes sticking out the top sides of the screw on the left side of the carb. The one on the left side adjusts the low speed air/fuel mix, the one on top is for the HIGH speed air/fuel mix, and the one on the right is your idel set screw just to keep it running at proper RPM w/o throttle. YOU NEED to have springs behind ALL 3 of these screws. If not the motor my or will viderate causing them to turn and go out of adjustment.

Now if for some reason you have Walbro carb. with NO top screw and both that look the same w/nubs are on the left side. Look next to the screw on the carb., one has an "L" and the other has an "H" stamped on the carb.. That top screw is now the one on the left side marked "H". Adjust accordingly as it were the one on the top of the carb..