Hi all, I have a question for the flathead experts out there. I've been working on my 1950 Ford F1 with V8 Flathead for 6-7 years now. Yeah, takes a long time. I don't get out to the shop all that often. I've done a complete restoration of the frame and engine so far. The engine has been complete and sitting in the frame for almost two years now. I leave the battery on trickle charge and give it a start every few months. It usually goes through a couple of quarts of fuel just fine. In fact I've run it around the yard a few times. No throttle control, so I leave it at about 1200 rpm and slip the clutch to run around the yard a time or two.

I broke in the engine with break-in additive. Except for having a full-flow oil system, the flathead is in stock configuration.

Now the question. I started it yesterday. It was about 80 degrees out. I ran it for a few minutes and then the RPMs started to decline. I tried to WOT, but it still continued to slow down, like it was over-rich but I don't think it was. I let it cool for a few minutes, although it didn't seem any hotter than normal. I then hit the starter again and it fired up just fine. Then a couple minutes later it did the same thing. If I didn't know better, I'd say it acted like it didn't have any oil in it and it was binding up as it got hot. Oil looked good. What could be going on?

 

What are you using for a gas tank?

 

I am using a plastic gas tank I have with a screw on plastic lid. It is about 2 liters I'd say. It is strapped to a running board support.

 

So no chance it isn't getting gas - hose sticking to the bottom of the tank, not vented, etc?

Usually the weakest point of a 6v engine is the condenser. Is it relatively new? A lot of them are no good right out of the box. They can do strange things. Is the coil hot when it dies?

 

I don't think gas flow is a problem. Fuel line exits straight down from the bottom of the container and the lid is vented. I also forgot to state that this is a 12v conversion. I'll try to run it some more and get more information next weekend. Thanks for your responses.

 

It's really not great for a fresh rebuild to be run without a load to seat the rings. I wouldn't overdo the periodic runs, other than those needed to heat cycle for head bolt re-torques.

 

If your rigged system is closed or has no vent then as you use fuel you will get a vacuum lock.

 

Well, I've only had the opportunity to run the engine one more time this weekend. Before I ran it I opened up the vent hole to a larger diameter in the plastic fuel tank I'm using, just to ensure there is no vent issue. The engine ran for a couple of minutes and once again slowed down and stopped. This behavior seems like it should be a fuel issue, but I'm not sure what to do to progress a resolution. This is recent behavior because it had run fine several times in the past.
What do you think guys? I hope it is nothing inside, like valve adjustment, cause I definitely don't want to crack this engine open again.

 

Not a valve problem, IMO. What, exactly was done to the engine when it was apart? You say it has oil and it looks good. How about oil pressure? With the air cleaner removed you should see two strong squirts of gas down a couple inches in the carburetor when the throttle is opened if it has fuel. If you do not see these squirts of fuel, you have a fuel problem.

 

The engine was a rust lump from the truck sitting in a field for years. It was cleaned, bored, new everything. It ran well for break-in and several runs around the yard. Like I said, I don't run it very often, but this is a new behavior. I don't know when I can get back out to work on the truck, but I'll check oil pressure then. The full-flow oil system does make the lines and filter warm, so I would think there is at least some flow.

 

When it stops, is there fuel in the bowl at the fuel pump? Will it crank over freely after it stops, or is it seized up?

 

There is fuel in the glass sediment bowl at the mechanical fuel pump. The engine will crank freely, just won't kick and run. Give it a few minutes and it will run again - then stop. Choke is used to start initially, then left open.

 

I'd be looking at the condenser and coil then

 

It sounds electrical. It could be connections on the primary lead..."battery cables" getting hot and losing conductivity. I suggest you inspect check and clean all connections.

A ballast resistor is needed for 12 v conversions. The porcelain Chrysler type from the auto parts stores are junk, they heat up and are not up to the task. When they fail they will do what you describe. I suggest a proper ballast resistor wire wired into the switch and coil Rock Auto has them...order one for a 64 f100. Local Auto store will give you a drooling blank stare when you ask for a " Ford Ballast Resistor Wire". Refer to the shop manuals 1960s in how to wire them correctly.

The coil could be failing. They do all kinds of things that's hard to diagnose. Also the main solenoid could be heating up causing a problem. I have had to pour cold water on them to get home. This can be related to poor connections and grounds.

Also your battery could be taking a sh*&.

It's unlikely it's the fuel system but Fords are sensitive to fuel mixture. Fuel pump is always a possibility as well as a vapor lock. I would simply check the electrical connections first and run a proper resistor.

Honestly, you need to get the body on and have these systems properly finished. Until then everything's a "Jerry Rig".

 

Everything has been sitting quite a while. Been busy with entering retirement and some trips. I just ran the engine with the same result. Wants to run well initially, then dies. I'm thinking it is loading up rich, but am not certain. I put a carburetor kit into the 2-bbl from The Early Ford Store, p/n 59A-9590. I wonder if it is up to the task of the 10% ethanol gas we use now, or if that is causing a seal issue. Anyone have experience with that? Thnx.