Technical Flathead First Start-up - Fuel in Oil!

As I was just about to start up my rebuilt flathead for the first time, I decided to check the fuel tank (1 gal from a lawnmower), and noticed there was no fuel left in it.
Then checked the dipstick, and it’s full of fuel. I’ve had fuel in the tank for about two weeks while getting things ready. After adding the fuel, I noticed leaks at all of my fuel line fittings. That took about 3 - 4 days to sort out, so lost some fuel from that, but not a gallon. Fuel tank bottom is above base of carb by about 16” or so.
Can someone help me understand WTH just happened, and what I need to do? I’m guessing a complete engine teardown.
I’m beyond words.

 

Drain it out, let it sit, fill with oil, turn the engine over a bit, drain and refill with oil.
I’d suspect the float stayed open and fuel went in through the carburetor.
You can pull the carburetor off, smell, look in the intake for signs of gas.
I can’t see there being a need to tear he engine down.

 

Check mechanical fuel pump diaphragm.

 

Almost no fuel left in carb reservoir. Has to be leaking through the carb somehow, and into the intake - no?

 

The chassis is now outside, so will need to bring it back in before I start tearing things apart.

 

Power valve leaking or stuck float . Is that a chinese carb ? Put a on off valve on the fuel line .
Drain oil add new and fire it up after you crank for oil pressure . Not a big deal , these are not rocket science. They were meant for farmers with tractors to be able to repair . Dont worry about zinc oil or any other nonsense . The cam pressure is not high enough to require special oil though I do use rotella for 20 plus years on 13 different flathead hotrods .

 

Remember, beauty is only skin deep . Get it running and start the rest of the assembly before you’re my age and can’t enjoy it !

 

So you are using a gallon tank 16 “ above carb. Gravity fed. If so this means its the carb needle and seat stuck or float in carb not properly set to shut off.

 

Pull the power valve...it needs not to have a radius where it seats against the underside of the bowl...if a modern PV was installed, with a radius...there is your leak
I am putting my money on this

 

I agree with the drain out the bad and replace it with new oil. With my model A with the stock tank above the carb I always shut the valve off before turning off the egnition just in case.

Phil

 

I rebuilt the carb from stuff I got at Vintage speed so PV should be good. Just got it back inside. No way fuel bowl should be empty. What would cause the fuel to drain from it?

 

Float was set correctly, but it was many years back now when I rebuilt it.
So, as folks mentioned, bad PV or needle not closing properly.
Will check it out tonight.

 

Is it wet under the carb, it it wet under fuel pump?

 

I should mention that I did notice the gasket between the carb and intake was “wet” with fuel the other day. Thought maybe it was “normal” considering all the other fuel leaks I had including same condition a fuel pump
diaphragm.

 

They do make a alcohol safe diaphragm for the Ford pumps.

 

Gravity fed, so not pump.EDIT: IT IS FEEDING A PUMP!
The only thing that holds the gravity pressure back is the float and needle and seat. However, if there is a leak internally, the level drops and the float lowers, allowing more fuel. I'd check it by removing the carb, filling the bowl and seeing if and where it's leaking.
I'd fog the cylinders and clear the intake ports since the fuel went down the engine.

 

He does have a fuel pump, if the diaphragm is bad it will leak to crankcase wether working or not.

 

All I can tell you is I feel your pain. I've been dealing with a different but somewhat related issue that I think I just got resolved and I know how frustrating this is. I doubt you need a full engine teardown but it might take some digging.

I don't know that I personally have any good advice but I would like to hear what the cause was once you figure it out, posts like this are really useful to future internet-searchers dealing with the same issues.

The pump diaphragm is one suspect, where fuel could get past and into the oil, although that doesn't explain the carb bowl being bone dry or the carb gasket being wet. Curious.

 

Possibly a combination... removing the carb as previously mentioned and filling the bowl would be telling watching it on the bench.

 

All engines end up with some fuel in the oil. It normally evaporates during operation. Drain the oil you have and disgard. Fill the engine with fresh oil, crank it with the plugs out, ignition disabled (the cylinders may have a lot of fuel in them) until you have oil pressure, put the plugs back in and fire it up.

 

you can test your needle and seat with a vacuum pump, or even with your mouth and tongue.
If it won't hold any vacuum, it won't stop the fuel. Sometimes a polish with tooth paste will fix the needle.

 

On the road now, but will tear into carb and test when I get home. Pulled the breather on the tube next to the fuel pump and didn’t smell any fuel when I was checking things out,
It’s easy to pull the intake and heads to check things out, but that’s about how far I would go for now depending on what I see.

 

Before you spin it, maybe shoot some mmo or trans fluid in plug holes just in case the gas did wash the cylinders and remove your cylinder lube.

 

If you do indeed find the issue with a power valve that has the radius on the mating surface, it needs to be flat, or cut flat on lathe. There's a fella in NY that specializes on 94s and has those power valves on hand already modified for this issue.

 

Dont waste more time and money on intake and head gaskets and wear on the head bolt/ studs . Something always happens , stripped headbolt or stud pulled threads etc . Check power valve , it doesn’t matter if you just rebuilt it , most all kits have the WRONG type of power valve . Only 2 ways to empty the fuel bowl , actually just one , the power valve . The seat and needle will allow fuel to fill the bowl and flow over but not empty it .

 

Charlie's your guy on power valves if needed

 

Ok. Makes sense to my monkey brain. Has to be something I buggered up in assembly as I clearly recall looking at the PV from Vintage Speed and checking for radius (there was none) as he claimed he was the only one selling them.

 

Gasket under PV?

 

Just so I’m clear, can someone confirm that the likely cause is that fuel flowed past the PV into the carb throat, then down through the intake and into some of the pistons (assuming intake valves are open), past the piston rings and then into the pan?

 

Take the carburetor off, set it on the bench and fill the fuel bowl and see if the gas will
run out. If it leaks it would about have to be the power valve or a hole in the carb body.