L head won't idle without choke

Finialy got the engine timed right and ignition system working correctly, but I had the carb rebuilt and it won't idle, even when warm without the choke. My carb is a Carter W-O. I have it set for 600 RPM idle with the choke. I have the A/F screw 2 1/2 turns out.

My first guess would be a vacuum leak, but I couldn't find or hear any. The float is set right.

The exhaust smells like the A/F is correct with the choke. Should it have a rich smell when idling? and then a neutral smell without the choke?

Engine is a fresh rebuild, done be a local professional engine building shop.

 

If making sure the idle speed screw and idle mixture screw are correctly adjusted as Glenn suggests and plugs are not fouled does not cure the problem I would gamble that there is a restriction of some sort in the idle circuit of the carb thats not allowing fuel to be pushed from the float bowl.

Possibilities would include, crud restricting a fuel passageway, plugged idle/low speed jet, wrong gasket between carb top and body blocking the fuel passageway ( assuming similar to yf ), there could be some crud in the small galley behind the idle mixture screw...........this could affect both the idle mixture screw and the off idle port just above it.

 

check firing order... i know its dumb but i have mixed up the order on my plug wires before. Makes it run like crap or not at all.

 

firing order is right. Flowed plugs was one of the first things I looked at. All the plugs were black. I wire brushed them cleaned, and regapped to .030. I think I have the idle set right. It idles at 600 RPM when the engine is cold, should this be like a high idle of 1200 RPM instead (when cold)?

I bought the correct master carb rebuild kit and gave it to the shop to do the work.

Give me a good reason to not throw this carb out the window. I have a few YF carbs from a f-head which I could use, But the base doesn't line up at all. Last resort for me right now is buying a Solex.

 

they are brand new, might have 1 hour run time on them

 

yes

 

Ok I will try that tomorrow and get back with you guys. It's a good thing I can get 4 new plugs for less than $10.

 

I had the exact problem for years. Drove it like that. Finally my buddies down here wanted it fixed.

I had just rebuilt the carb and still had the same problem. They swapped the carb with an old one that had been sitting on the shelf for at least two years. Fixed it. Problem was sloppy shaft. Alowed fuel and air leakage. No rebuild can fix that. Buy a new Solex or a good Carter and be done with it.

 

thanks, and I probably will. I think I will test this by "stealing" the carb off my Dad's truck R)

 

carb from a ford Falcon is a nice swap. thats what i run on my flattie

 

will look into it. does it fit the intake manifold? or do I need to make an adapter plate?

 

yes, but you mist adjust the A/F mixture at idle. I have the idle adjusted on the linkage at 600 RPM according to my tach. I push the choke in and it stalls out, even when its up to operating temp of 170 degrees.

 

My friend had a fun little gauge for testing A/F mixture. We checked the mixture at a 600 rpm idle and it was around 12.6. It was a wonder it even ran. We did 3 tests the first was 2.5 turns out, one was .5 turn out, and the last was 4 turns out. the number stayed about the same for all 3 tests. I took the carb off my dad's truck and checked it. 14.1 right about where it should be at 2.5 turns out.

The lean mixture also helps explain the overheating problem.

So I splurged for a Solex from Walcks. I am also getting a 2 PSI fuel regulator because my electric fuel pump puts out around 3 PSI, which according to carl is too much for a solex.

 

got it in, installed, but the local engine shop tells me I don't need a regulator, and the mechanical pumps pushed 6 PSI through this carb all the time. DO I REALLY NEED A REGULATOR?