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Carb question

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curt1968

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I rebuilt my 1960 JW-16 3hp Johnson carburetor and everything appears to be clean and components all correctly set.
I have to pull the choke out to start it and even then it only runs for a few seconds and then the carb floods with fuel.
Fuel runs out the choke side bore behind the air silencer. I have to assume there is something amiss with the float setting
but I just don't see anything incorrect with how I set it up. Parallel with the body and the needle appears the seat.
Is there any suggestions on what else I should check?
 
Gotta be something wrong with the float or float valve. The vent is not blocked as we know because the gas is pouring out through it. Back to the float / valve
 
I tried blowing through the fuel inlet and did find that right side up I can blow air through carb and cannot blow air through it
upside down. I believe that at least tells me the needle is seating? I think I really need a more complete understanding of exactly
how the carburetor functions.
 
If you're saying that fuel flows out the carburetor "with the engine NOT running"... simply fuel draining down from the gravity fed fuel tank, that indicates that the float may be upside down, or adjusted improperly, or.............
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(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
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If the float is set correctly and the carburetor still floods, see below
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Even though there is a passageway for fuel to flow out of, there is another air vent leading from the float chamber that is difficult to find that occasionally becomes clogged with ant debris or some such matter that results in what you have described. Look for vents in the outer body that you cannot pressurize to have the air escape elsewhere.

Let us know what you find.
 
I would have to say your CHOKE is working very well.-----Tilt the motor back so that that fuel runs towards the engine and you can not see it !!
 
Couple things to check. Make sure the float bowl is not distorted and the fuel is not running internally, unchecked into the float chamber through the "transfer port". ***also note Joe's post #4*** Secondly you must be assured that your fuel tank is SPOTLESSLY clean and the fuel is being FILTERED between the tank and carb. I often replace the composite filter with a small, high quality, in-line filter that I can see into when the lower cover is dropped. I am restoring a "Lightwin".......on the side......and the tank was filthy, had to use acid to clean it. The motor came from an auction and of course the auctioneer said that "it RAN". Yup, everthing "RAN" at one time.
 
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Are you sure that float valve sits nice and tight in its place? Is the float valve gasket good?
Hopefully you find the problem, i just did same rebuild to similar carburetor during my engine rebuild.
 
Hi, Evin, I am restoring a motor just like your last project. It will not look as nice.....by a long shot.....but I hope it runs just as well.
 
I completely went thru carb today and paid closer attention to all the passages making sure all were clear.
I agree with racerone that my choke is working very well. Shouldn't need to choke it in 80 degree weather.
I suspect now that perhaps I am not getting sufficient spark. I am going to go thru my ignition system. The
coils ,condensers, and points look brand new but I don't know for sure they are timed correctly. Do you have to
have a VOM meter to check for proper timing of points opening and closing?
 
No, you can carefully gap to .020 and remain accurate as long as there isn't too much play in the stator plate. An ohm meter can be used (set at par "1") to check for points continuity. (must be NO resistance.....a perfect short) Test with wires removed from the points, (at least the coil wire). You can test spark at 3/8" gap and look for a nice "crackling" blue/white color.
Note: Make sure that the "donut" seal at the base of the float chamber, as sealing very well. If any fuel is leaking past it, you will have rich running and high speed needle will not function properly. If the leak is minor, it will be adjustable by closing in the high speed needle, never the less you will eventually have to deal with it. On fixed high speed jet motors, any leak here will richen low/mid, mid, and high speed operation. This is a VERY IMPORTANT SEAL.
 
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I want to check my compression, I want to know if I need to ground the spark plug wires. If so, would a lead with one clip end inside
wire boot and the other grounded out on motor somewhere work? At 6 to 1 compression does that amount to 87 psi being the most compression
I can expect to see? Seems like I read that in a post somewhere in the forum. I have also heard two different opinions regarding compression
readings accuracy. Are cold engine compression numbers accurate? At the moment I can only do a cold test.
 
Grouning the plug wires is good practice. Your suggested method is perfect. 80psi is good. You bring up a good point, how you gonna test warm compression on a motor tha won't run? Of course cold is the correct way.
 
Trying to get an answer on whether or not the little arrow stamped next to the word TOP on the points cam
is where to align rubbing block to set points to .020. I have read to align with the key, put in middle of where
it is stamped TOP, and my manual just states high of cam. Looks too me that I just rotate the shaft until the
points are at their biggest opening and that should be the high of the cam. Not experienced with these and just
want to make sure it's not one of positions that experts have found work better than what the manual is saying.
 
The questions / uncertainty would disappear if you used the timing marks on the flywheel and magneto plate.----You use a meter too.-----That way the points will open at the correct time with regard to magnetic flux / current in the coils.-----Gets you the strongest spark and an easy to start motor.
 
thanks racerone, the notches in my flywheel are two different sizes. Does one size indicate the top cylinder and the other the bottom?
 
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You could erase all that stuff from the top of the cam and still the fact remains that the high side of cam is where the points open at their widest---just what the book says. As for the keyway issue, that is the end of the high side of the cam (when rotating clockwise), so yes perfectly acceptable as a set point on your 1960. You guys with LoTension mags ignore this.

Timing marks: Fine for getting it perfect but not necessary for most cases. Set at 0.020" on high side is "good enough"
 
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Just did a 1969 Johnson 6 and with a "swift pull" I get a 1/2 INCH CRACKLE. THESE FANCY NEW CDI units got NOTHING on this antique old garbage.
 
Well I am very disappointed, finally got around to being able to check compression and can only
get readings of 15 psi. I believe I'm using the tester correctly. Must be junk.
 
Carefully remove the cylinder head, these gaskets often failed. You may not be washed up yet. My latest 3hp has a strong 70 psi. That's fantastic for these. Also took a 1964 in on trade that was dry seized, broke free with a quick soaking but haven't checked compression yet, gotta fix the recoil. They will run great with 50 psi even.
 
20190703_202711.jpg Quite a bit of carbon build up, I was able to poke each ring with a small screw driver and they have some spring to them. Gonna clean, resurface , and replace gaskets and retest. Gasket seems really old.
 
Remember clean well gasket-surfaces but dont damage them. Work slowly when putting new gasket, check that new gasket sits right way in its place, use right torque on bolts. And why not clean water passages and piston heads at the same time.
 
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