Not an antique, but I need some help.

[legendre]

Unclear on one thing.. when you say the needle was stuck in the seat, do you mean the fuel metering needle (#35), or the fuel inlet valve needle (part of assy. #33)?

If the former (metering) why was the needle stuck? Did some dope "snug it up real good" or was it stuck with varnish / corrosion?

BTW, it’s perfectly fine to use a strand of plain copper wire to help clear a badly plugged jet. Find a 4" length larger multi-strand wire, like 14-16ga. and strip off a couple inches. Use one strand at a time to poke / drill out only the most difficult jets. If you have a nice, sharp flush cutter, you can cut a strand at a 45′-60′ angle to form a sort of drilling tip on the end. And yes, jets are easily damaged and you don’t need to accidentally oversize one to ruin it. Just putting a scratch or two in the right place can mess up the fuel stream enough to cause issues for carburetion.

[wiscoboater]

It was part of assembly 33. I replaced both the needle and seat, and hooked the small wire clip on the new needle to the float arm. It seems like everything is pointing to "I screwed something up" when I rebuilt the carb. I guess I will look that over again. Everything else on the motor points to it should run good. I will also look over the fuel lines for air leaks as well as the carb shaft bushings. Anyone else ever deal with this? You have a motor that seems like everything is right and it just kicks your butt?

[chris-p]

Nah, every motor I restore fires on the first pull in the barrel and runs like a dream 🙂

Kidding of course, its the challenge that keeps us interested right.

[wiscoboater]

What should the float level be on this motor? When I rebuilt the carb I used the BRP kit that came with the new float. The BRP kits do not come with instructions, so when I installed the float I matched the level to the old one.

[chris-p]

Float should sit level with the carb body flange when inverted.

Although, I set them with the unhinged end slightly higher than the hinged end. This ensures the needle seats when the bowl fills and it does not flood.

[Mumbles]

When set properly, there will be a slight gap between the carb body and the float.

Scroll down a bit here and Max has a picture.

http://www.maxrules.com/fixtuneitup2.html

[wiscoboater]

Thanks Mumbles!

[legendre]

Credit to Mumbles for finding this..

This is fine, if the float needle doesn’t have a spring-loaded plunger that contacts the float tab. If it does, then you can’t hold the carb fully upside-down, as the weight of the float will compress the plunger and make it appear as if the float is set way too high.

To gauge float height in those cases, only turn the carb far enough into the vertical that the float tab contacts the needle but doesn’t actually compress the spring plunger.

[fleetwin]

OK, so you just got the engine, it wouldn’t run because the float needle was stuck closed, correct? So, you really don’t know the engine’s history or how it ran for the previous owner. You have checked compression and it is good.
First, on their best day, these engines were very cold blooded. The love to sneeze/fart/cough during warm up and are tough to keep running without tickling the choke. So, please don’t expect this engine to idle like an 18hp from the 50s. The initial needle setting for the carb is 1.75 turns out from gently seated. It is real tough to get a consistent idle from these engines, trying to smooth the idle out by leaning the needle usually results in a lean spit, you usually have to leave the adjustment slightly rich to avoid the lean spit.
You mention that the engine won’t idle, but runs OK at higher speeds. If this is the case, a plugged/restricted high speed jet seems unlikely. In any event, you need the special tool to remove it to avoid damage. If you don’t have the tool, simply remove the bowl and carb drain plug, then just look through the jet by shining a strong mini light down the bowl nozzle. Spray some carb cleaner through the jet, then run a small pipe cleaner through it. The felt on the pipe cleaner will show gum/crud when removed from the jet, avoid poking through the jet with wires/drill bits. I think I hear you saying that richening the needle has no effect at all on the idle quality/sneezing. I know you said you had the core plug out, so I will "asssssume" the low speed needle is in good shape and not broken off in the idle pocket passage.
This carb does not have the conventional packing nut/washers to seal the low speed needle. These carbs have a plastic "retainer" (29) that holds the needle from turning and helps seal the needle. Some of the carbs on the larger engines had a plastic cup seal around the needle as well, but it doesn’t look like this style carb has that seal.
I guess I am getting ahead of myself here though, are you sure the carb butterfly is closing fully, not jammed/binding? Is the carb/timing synced properly? This engine will not idle if the butterfly is partially open at idle. If you have the carb off, look in at the butterfly from behind the carb, make sure it is closing fully, not binding, and has not been messed with. Do not attempt to remove the butterfly or loosen the retaining screws. Did someone misadjust that "economizer" linkage, perhaps that is holding the butterfly open slightly at idle. The other thing to keep in mind is these engines won’t idle if they are running cold, especially in cold weather, probably not much of an issue now during the hot summer though.
Like others have said, sometimes ignition problems disguise themselves and sound like fuel problems. This engine should be able to jump a half inch gap on the spark tester while cranking. There isn’t much that can affect ignition timing at idle. I suppose the flywheel key could be sheared leaving the spark retarded, wouldn’t be my first guess though. Does it look like someone has been messing with the flywheel nut?
Finally, the idle speed on this engine is controlled by the plastic spring loaded idle set screw located on the vertical throttle gear under the engine pan. Is the spring loaded screw in place? Can you move it? Keep in mind that the throttle settings called out on the plastic collar under the twist grip are rarely accurate. In other words, don’t worry if the engine won’t idle much below the start/shift throttle settings, as long as the idle speed is low enough and idle quality is "acceptable". Trying to dial the idle in and make it idle on the "slow" setting will be frustrating and normally not possible.

[wiscoboater]

quote FrankR:

Trash in the idle ports under the #5 core plug? #2 Lead shot missing? That carb looks a bit different than what I’m familiar with. Does the idle mixture control air instead of fuel?

I have been studying the drawing and have a question about #2, the lead shot. Does #2 go in the well below the core plug and just free float around in there? It’s kind of unclear from the drawing. I do not remember finding one in there when I took the carb apart, and I did not put one in on re assembly.

[Author]

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