8N carb leaking air??

[davidl1632]

My 1952 8N has good spark, new plugs, and gas to the carb, but will not fire. Cylinder compression is good. Air cleaner is clean, so could a
loose shaft in the (original) carb or blocked carb passage cause lack of fuel to the cylinders?? This driving me nuts.

 

[Bruce (VA)]

6v or 12v?

Does the spark jump 1/4" in open air? How did you check spark?

If you remove the bolt in the bottom of the carb, will the gas fill a pint jar in less than 2 minutes?

What is the compression?

Tried starting fluid?
75 Tips

 

[davidl1632]

6v. Gas flow is good. Checked compression last month and each cylinder met specs. Will check spark for 1/4" jump in the morning. Thanks for your counsel as always Bruce!

 

[Caryc]

(quoted from post at 12:47:11 11/03/16) My 1952 8N has good spark, new plugs, and gas to the carb, but will not fire. Cylinder compression is good. Air cleaner is clean, so could a
loose shaft in the (original) carb or blocked carb passage cause lack of fuel to the cylinders?? This driving me nuts.

Spray some starter fluid around that carb while cranking the engine. See if it will suck the fluid in and try to fire on that.

 

[Bruce (VA)]

Try starting fluid too.
75 Tips

 

[HCooke]

I went thru this recently myself. Had fuel thru the carb, had what I judged to be good spark on all four cylinders, had a fully charged battery. Even though I had what I thought was good spark, I replaced the points and it started easily. This may not be your problem, but if you haven't changed the points recently, I would do that. I have several N tractors and when they become hard to start it is almost always the points.

 

[Tall T]

In addition to what H Cooke said,
I never do points without also chipping the scale off the distributor cap internal poles, cleaning the tip of the rotor with 400/600 emery and twisting fine steel wool into each cap tower.

Small wire wheels on a drill work well inside the cap too -- after chipping off the pole buildup.

 

[Royse]

To answer your question directly, a leaking carb shaft may cause
run-ability issues but I have never seen one cause a no start.
A plugged passage in the carb can cause a no start condition.
Depending on what passage it is.

You said gas flow is good. That means out of the drain on the
bottom of the carb it will run a pint in two minutes right?
At the line is not the same test.

If gas flow is good through the carb, try using your palm to
choke it by holding it over the throat of the carb with the
breather tube disconnected. Expect to get your hand sucked
to the carb and to get some gas on your hand.