Baffelled with this cub

Anonymous-0 · May 15, 2012

Picked up a 1951 cub. The guy used it to mow his grass up till 2 years ago and rebuilt the engine prior.
After I cleaned up the carb, it fired right up, then ran about half speed then died. Full throttle the whole time. Messed with that carb the entire day.
So, bought 6 volt electronic ignition and a 50,000 volt coil. Same thing, ran great, then died down to half speed and then died. Would not start.
So, bought a brand new carb. And it did the exact same thing. Fired up a few time with starter spray a few times, but that quit working.
Thinking the intake manifold now, but it looks a lot better than my H.

John730D · May 15, 2012

Do you have a GOOD unrestricted flow of fuel to the carb? Maybe someting the tank. Sounds like a fuel problem to me.

Anonymous-0 · May 15, 2012

First carb, no. Second, yes. I removed the plug in the bowl and it flowed nicely.

teddy52food · May 15, 2012

How is the spark when it doesn't start? Condenser can do that too.

mkirsch · May 16, 2012

Winger, first thing stop throwing parts at it. I'm sure you're not made of money and quite frankly you've spent way too much already. Electornic ignitions are wholly unnecessary especially when you don't even know if the engine is any good yet. A $30 tune-up kit from Tractor Supply is more than adequate. Rebuilt carburetors are a total scam. There is absolutely no need to buy a rebuilt carb unless yours is smashed or missing completely. You can rebuild it yourself for about $30 and end up with the same thing as what you probably spent $250 on.

The biggest problem with rebuilt carbs is that they are shipped. During shipment they are treated like footballs. What do you think the float adjustment is going to look like after a carburetor has been thrown, kicked, tackled, dropped, rolled, and crushed? Your rebuilt carb may be no better than the one you took off.

I don't think you have a manifold problem either, because your symptoms do not match a manifold problem.

I still think you have a fuel flow problem. When the engine starts to die, pull the choke. If the engine runs better, you have a fuel flow problem.

glennster · May 16, 2012

i agree with the fuel problem. peek down in the fuel tank and see if there is any junk in there. i would drain the tank and flush it out good. then clean the sediment bowl and blow that out real good. if you have an aftermarket in line fuel filter on the tractor, get rid of it, unless it is a full flow filter for a gravity flow system. (napa 3031 or 3032 are two full flow models). also try running the tractor with the gas cap loose. could be a venting issue also. also, try running the engine with the air cleaner pipe dis-connected from the carb. could be a plugged up air cleaner too.

evilboweviel · May 16, 2012

I agree

rustyfarmall · May 16, 2012

(quoted from post at 05:20:32 05/16/12) Winger, first thing stop throwing parts at it. I'm sure you're not made of money and quite frankly you've spent way too much already. Electornic ignitions are wholly unnecessary especially when you don't even know if the engine is any good yet. A $30 tune-up kit from Tractor Supply is more than adequate. Rebuilt carburetors are a total scam. There is absolutely no need to buy a rebuilt carb unless yours is smashed or missing completely. You can rebuild it yourself for about $30 and end up with the same thing as what you probably spent $250 on.

The biggest problem with rebuilt carbs is that they are shipped. During shipment they are treated like footballs. What do you think the float adjustment is going to look like after a carburetor has been thrown, kicked, tackled, dropped, rolled, and crushed? Your rebuilt carb may be no better than the one you took off.

I don't think you have a manifold problem either, because your symptoms do not match a manifold problem.

I still think you have a fuel flow problem. When the engine starts to die, pull the choke. If the engine runs better, you have a fuel flow problem.

Sorry there Mkirsch. I have to totally disagree as I have rebuilt way too many carburetors that were nearly destroyed by do-it-yourselfers. Carburetors are NOT simple. In fact, they are VERY complex, and more often than not throwing a $30 kit at one will be a total waste of $30, and you will still end up either sending it to someone who KNOWS how to rebuild a carb, or you will end up buying either a professionally rebuilt OR a NEW carburetor.

mkirsch · May 16, 2012

Sorry there Mkirsch. I have to totally disagree as I have rebuilt way too many carburetors that were nearly destroyed by do-it-yourselfers. Carburetors are NOT simple. In fact, they are VERY complex, and more often than not throwing a $30 kit at one will be a total waste of $30, and you will still end up either sending it to someone who KNOWS how to rebuild a carb, or you will end up buying either a professionally rebuilt OR a NEW carburetor.

We're not talking about a Holley Street Avenger here.

We're talking about an IH 3/4" updraft Cub carburetor with a total of FOUR moving parts (choke butterfly, throttle butterfly, float, and needle). The only adjustments are float level, idle speed, and idle mixture, and those aren't all that fussy.

Don't care what you think, it's not rocket science.

Anybody can ruin a carburetor if they're completely ham-fisted about it but if you're the slightest bit careful you don't HAVE to ruin the carburetor.

Anonymous-0 · May 16, 2012

Thanks all. Will give another go when I get back.

rustyfarmall · May 17, 2012

(quoted from post at 10:47:50 05/16/12)

Sorry there Mkirsch. I have to totally disagree as I have rebuilt way too many carburetors that were nearly destroyed by do-it-yourselfers. Carburetors are NOT simple. In fact, they are VERY complex, and more often than not throwing a $30 kit at one will be a total waste of $30, and you will still end up either sending it to someone who KNOWS how to rebuild a carb, or you will end up buying either a professionally rebuilt OR a NEW carburetor.

Click to expand...

We're not talking about a Holley Street Avenger here.

We're talking about an IH 3/4" updraft Cub carburetor with a total of FOUR moving parts (choke butterfly, throttle butterfly, float, and needle). The only adjustments are float level, idle speed, and idle mixture, and those aren't all that fussy.

Don't care what you think, it's not rocket science.

Anybody can ruin a carburetor if they're completely ham-fisted about it but if you're the slightest bit careful you don't HAVE to ruin the carburetor.

Cub carburetors have a tendency to warp. Most folks won't even notice it, go to the work of rebuilding, and it still won't run. I'm sticking to my guns on this subject. Carburetors are NOT simple. Not even that little thing on a Briggs and Stratton.

Baffelled with this cub

Anonymous-0

Well-known Member

John730D

Well-known Member

Anonymous-0

Well-known Member

teddy52food

Well-known Member

mkirsch

Well-known Member

glennster

Well-known Member

evilboweviel

Member

rustyfarmall

Well-known Member

mkirsch

Well-known Member

Anonymous-0

Well-known Member

rustyfarmall

Well-known Member

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