Fuel System: 1939 Champion with Sticking Float in carb?? (I believe)

[johnnypro]

I took my '39 Champion to a local Cruise (Guptal's in Upstate NY) this week. It ran fine to there (approx 15 miles), but began to smoke a bit with a strong smell of raw gas coming from the motor. It was also idling real rough. The guys from my chapter of the SDC said it was perculating and or leaking gas. We tightened any loose screws on the carb and let it sit for the 3 hours I was there and it started back up without too much trouble. I drove it home OK being careful not to let the idle get too low and made it OK. It was idling rough when I got home.

In asking friends, I'm getting answers of everything from Carb re-build to spacer gasket on the carb (to keep it cooler) to re-adjust the carb. The engine was completely rebuilt only about 200 miles ago, but that was 18 years ago. I've only had this happen once before in the 4 months I've owned the car. Any ideas??? I haven't done carb work on a car in 30 years so help!!!!!!!!!!!!!!!!!!!! Thank You in advance!!!
:-) JP

[nvonada]

I always assume ignition first. Your symptoms could be a miss too. Rule that out. While doing that check the plugs. They will be black and sooty if the engine is running rich. If so it could be a float problem but I would check the choke first. If you only have 200 miles since the rebuild anything could be wrong. Way too soon to start tearing the carb apart.

Nathan

[jclary]

I took my '39 Champion to a local Cruise (Guptal's in Upstate NY) this week. It ran fine to there (approx 15 miles), but began to smoke a bit with a strong smell of raw gas coming from the motor. It was also idling real rough. The guys from my chapter of the SDC said it was perculating and or leaking gas. We tightened any loose screws on the carb and let it sit for the 3 hours I was there and it started back up without too much trouble. I drove it home OK being careful not to let the idle get too low and made it OK. It was idling rough when I got home.

In asking friends, I'm getting answers of everything from Carb re-build to spacer gasket on the carb (to keep it cooler) to re-adjust the carb. The engine was completely rebuilt only about 200 miles ago, but that was 18 years ago. I've only had this happen once before in the 4 months I've owned the car. Any ideas??? I haven't done carb work on a car in 30 years so help!!!!!!!!!!!!!!!!!!!! Thank You in advance!!!
:-) JP

My response might be interpreted as out of place here, but...sometimes...I think there is a higher power that places little problems in our lives just to keep, otherwise fairly educated people, humble. Lest we become too full of ourselves to the point of looking down on the troubles of others with no compassion. I have been exactly where you are, and with a vehicle that is ONLY 69 years old, and not 78 like yours.

Truth is, for any of us who had a perfect running car yesterday, might encounter the same bewildering situation today. These problems may have several causes resulting in the same symptoms. A tiny bit of microscopic trash stuck between your needle valve seat and the needle, could cause it. A manifold air leak, that worsens with heat expansion, or an electrical/ignition value that changes as the engine warms. There are tiny clearances that mean a lot to the operation of any mechanical device. The key is to not become so fixated on one problem, so as to ignore or exclude the real culprit. It takes discipline not to "monkey" (my term) with only one setting at a time.

Your "smell assessment" of raw gas, could be a clue of contaminated fuel (moisture?) if it either smells of incomplete burn, or old gas. Especially coming from the tailpipe. Fuel tanks, and carburetors have recessed areas in their reservoirs below pickup level for the accumulation of small contaminants. These contaminants will settle to the bottom, but can become suspended into the active fuel flow with the vibration of motion. It don't take much water in the bottom of a carburetor bowl to get sucked into an engine to foul up the operation and create havoc.

My encouragement is to do the "easy/cheap" stuff first. Check vacuum lines, ignition components, etc., (even if relatively new), before rebuilding or replacing the carburetor. If you tackle the carb, carefully open it first, and inspect for contamination, tiny trash or sediment. If it has not been removed, check for trash in the tiny fine mesh filter screen at the carburetor inlet fitting where the fuel line is attached. It is very often overlooked. When you finally solve the problem, let us know what it was. We can all learn from your frustration.

[altair]

I believe John Clary has it in his text "a tiny bit of microscopic trash stuck between the needle and seat". Early needles were made of steel with out the rubber tip and as the fuel passes by it a static charge is created and microscopic metal particulate will be attracted to the needle causing flooding. Some times the particulate will pass through and other times it will stick. The cure is to replace the needle with a rubber tipped needle and a sediment filter before the carb.

[johnnypro]

I don't think it's old gas as I know it ran out of gas when I was there to look at it 4 mos ago and it's been fresh gas since. Dirty gas is a possibility. Looking thru the suggestions above and have a friend who wants to do the carb. I guess we'll try to figure it out and let you all know here. Thanx!!! JP