Technical Flathead First Start-up - Fuel in Oil!

Did any gas come out of the exhaust? That's the path, with rings being the "boarder".

 

Only way is through the carburetor, or maybe? the diaphragm on the fuel pump, but I doubt that.

 

Thats the usual path when the carb is leaking from its bowl . If the pv was good ,a stuck needle and seat or a bad float ( hole in it ) fuel would still follow the same path BUT the fuel bowl will still have fuel in it .

 

Yep. Will do for sure. Will have to wait until tomorrow though.

 

Don’t know. I assume there is no way to tell really unless I pull the exhaust

 

Just drained the oil. Looks almost good enough to try a sip or two…

Forgot I had added a magnet to the drain plug.

 

Looking down the breather tube, I don’t smell any gas, but who knows at this point.

 

Closer pic of fuel setup.

 

Let me get this straight. You were going to start a new engine for the first time and you checked the fuel tank and found that your carbs needle valve had leaked and all the fuel went into the oil as indicated on the dipstick.
What I can’t figure out is how in the world you jumped from that to a complete engine tear down.
Can’t figure that one out.

 

I'm getting a bad feeling about this whole endeavor. It seems that there is a dark cloud hanging over everything. I have been though times like this before, and when I run into this many problems. I go back to the beginning and start over.

If it were me I'd go back to step one and start over. This would include replacing all of the second hand fuel line components (which may include the fuel pump and carb) with new, proper parts and make sure I had a solid system before proceeding any further. The first start of a new engine is not the time for testing whether your leftover fuel fittings from the last project are functional.

 

Yep, still not sure how fuel leaked out of carb.
No professional engine builder, so just assumed fuel in pan means fuel contamination “everywhere”. Perhaps you can help me understand where fuel travelled
and why, and what I should/should not do and why?

 

First step is to add an inline fuel cut off somewhere from the tank to fuel pump. Lawn mower places sell them and they are easy to get. Don't make the same mistake twice. Having the tank 16" above the carb, gravity is creating some pressure. Do as others have mentioned, but it either came from the fuel pump or the carb. Only two possible places. Need to figure out which one.

 

Yep, sometimes I feel there’s been a black cloud at times, but I just keep plugging along. This whole endeavour has been and still is a huge learning experience, and I feel pretty comfortable working around vehicles. The “big day” was a longtime coming, and I tried to ensure everything was in order as best I could.
I rebuilt the distributor, carb, fuel pump, and oil sump pump all myself using parts from reputable suppliers. Seems the fuel leaks I struggled with were all solved using all original Ford fuel fittings that were of the 45 degree flare style. These all came from a second flathead I bought last year, or from an extra orig 94 carb and misc orig 94 carb parts I had lying around.
Not sure yet as to what exactly I’m going to do. Of course, I need to find out why/how the fuel was leaking from the carb and address that issue, but as far as the engine, and what needs to be done or not to be done, I’m hoping for more input from HAMBERS.

 

Take a chunk of plywood. Drill the holes to mount the carb and fuel pump to it. Remove from engine and mount on ply. Hang the tank above. Should be fairly easy to catch the bad guy.

 

There is a petcock shut-off valve at the outlet of the tank. I had opened it up initially to fill the fuel line to the carb. It was at this time that I found the fitting (nut with ferrule) was leaking at the sediment bowl inlet just from the gravity effect of the fuel sitting in the tank. So, I had left the valve open to see if the connection was still leaking after I thought I had fixed it only to find two additional leaks at the carb inlet and then later at the pump outlet. I have a whole thread on the Barn about these damn leaks. I thought I was losing my mind. lol!

 

Decided to pull the carb tonight. Separated the upper half and added about 1/2” to the fuel bowl. Almost immediately the face of the mating surface of the base is wet with fuel. Can’t see where the fuel is coming from yet.

 

Now wondering if it could be the gasket between the base and the main body?

 

Also, check the gasket between the PV and bowl. At this point, every rock is worth turning over. Any Strombergs laying around...?

 

At least, you can concentrate on the carb with those findings.

 

So, reading up/watching vids, I understand that the PV requires a vacuum to remain closed and only opens when manifold drops below the rating on the valve (e.g. a “6.5” value on the PV means valve opens when manifold pressure drops below 6.5”). So, what keeps it closed when engine is not running and when there is no vacuum?

 

I don't think the issue is wither the valve is open or closed under vacuum or not. The vacuum source for the power valve is right under the PV. IF, the gasket for the power valve OR the diaphragm in the power valve is damaged, it will leak gas down in the intake. All it takes is one good backfire and you can rupture that diaphragm.
The cavity under the power valve is meant to be "dry" and just for vacuum the activate the PV. If you seperate the cast iron base from the bowl and its wet, you should find the culprit.

 

I had a mystery 94 that emptied its self. Numerous rebuilds with quality kits. This was many years ago . Set it on wood blocks over newspaper. Sure enough over night the paper was wet. Top came off for the umpteenth time. Well bugger me , the fuel was actually percolating up the wall of the float chamber. I did take pictures to prove it but lost them . Fuel level was spot on . Can’t remember what I did, probably found a better carb that behaved better.

 

Ok. This makes sense looking at the pics, but I’m still at a loss in terms of understanding the PV operation. Nevertheless, I’m almost 100% positive this is where the fuel is coming from, so then like you stated, it’s either the seal around the PV or the diaphragm itself. I was watching a vid last night, and in theory you can test the PV with a hand vacuum pump, but a fixture is needed. Will try to get a hold of Charlie at Vintage Speed where I bought the kit to see what he thinks. Will also speak to the machinist who rebuilt the engine to get his thoughts on the situation.

 

Thanks for sharing. Now I feel better. Haha! The fuel line connection leaks and now this leak have really pushed my patience. With all the things I’ve had to do to get to this point, I never could have imagined that the fuel system would be the Achilles heal.

 

Spoke with my machinist and he concurs with what folks here have suggested. I’m going to remove the spark plugs, give a shot of oil to each cylinder, fill with fresh oil, give a few cranks by hand, drain oil, refill again with fresh oil. Will have that done this afternoon. Still trying to reach Vintage Speed.

 

You trust Charlie Price?

 

I would think one fresh oil change would be sufficient. All the contamination was in existing oil. Any gas in residual oil clinging to internals has or will evaporate.

 

Just got the phone with Charlie at Vintage Speed. He confirmed it’s either the PV or leaking through the clusters due to a siphoning effect because the tank is higher than the carb. He also stated every PV is tested, so perhaps it’s the seal around the PV. He also recommended lowering the fuel tank and having a way to close the tank valve when not running as folks here have already suggested.
Checked the carb again, and it’s definitely leaking past the PV and into the throat via the vacuum passage. Will now remove PV and see what’s going on. I think I have a new spare from another kit, but IIRC, it has the radius on the sealing surface.

 

Yep so far. Never had issues with him. Can’t speak to quality/function yet though of his parts. We’ll see…

 

To help you with the operation of the PV.
The bowl has a set level of gas in it. Every designed circuit that allows fuel into the carb throat is going to at some point go above this level. Think garden hose that is in a bucket to siphon. Even the idle circuits that are below the throttle plate go above the gas level, otherwise they would just drain the bowl.

Each of these also have a hole in the hose where it goes over the top edge of the bucket, or else as soon as the hose is filled with gas, it will siphon all the gas out., These are the air bleeds. If plugged, the gas will siphon!
When running, the engine pulls enough vacuum that it sucks both air thru the little hole and fuel through the hose.