1964 Oliver 550 carburetor jet not large enough?

Ed_129

New User
I recently replaced my intake/exhaust manifold because my old one was cracked. I also bought a used carburetor, but I took all jets and replaceable components from the old carb and put it in the one I received. I used my 550 this weekend to disc and I had to choke the carb to get it to run correctly. At an idle, it seems okay but once you put it under load it seems to be starving for gas.

I have tried adjusting the air mixture screw and bottom jet but nothing seems to make a difference. If you have any hints, please let me know. Thanks, Ed.
 
Ed, Do you have a good seal between the intake manifold and the head? A leak there would also cause the lean condition you are experiencing. Chuck
 
You may have a plugged circuit in the used carb. Take it apart a put it in a cleaner tank. I did one three times before I got it to work properly. You may also need to bore out the main jet.
 
Check that the new main jet is bored out to the correct size opening. I had a similar problem in 1987 on my 550. Details that I posted should be in the archives - search!
 
I can't find my previous explanation! In overhauling the 550, I wrung off the jet when putting the carb back together. Ordered a new one (from White - same part number stamped on the jets) and put it in. Like yours, tractor would run fine at idle, but had to be choked for any higher speed. Kept trying to clean out and find anything in the carb. Subsoiled, disked, and sowed 10 acres of pasture. Took the carb apart one more time. Happened to think, is the hole in the new jet as big as in the broken one. Checked with a drill bit - NO! Drilled it out to the same size as the old broken jet and didn't have to use the choke from then on!
 
I have drilled out several load jets. You still have the needle to close it down. You ought to be able to get black smoke out of any carb if the jet is big enough. Then you can turn it in and clean it up. You need a set of wire bits with decimal sizes to do it right. A normal 32nd or 64th drill bit set is not adequate. For example I went from .053 to .070 on one carb. Just go a little at a time. Some carbs also have an economizer jet in them that has to be opened up.
 
Thanks for all of the advice! I will get a set of metric drill bits and try it the next time I'm at the deer lease.

Ed :lol:
 
Not Metric Bits, but Letter size is what you are looking for




(quoted from post at 12:52:24 08/24/16) Thanks for all of the advice! I will get a set of metric drill bits and try it the next time I'm at the deer lease.

Ed :lol:
 

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