Engine fails out if very hot

Guten Abend Ford-Freunde.


I can now rule out that the ignition system faults. I checked the timing marks with a strobe light; the sparks persists even when the misfires occur and the engine eventually stalls. It has a Nurex ignition advance unit.

I use only ethanol-free gasoline because the engine runs more smoothly on it. I’ve also run Avgas 102 at some times; you can really feel the difference, the engine runs remarkably smoothly with it.

I’m going to measure the free-flow rate again. I read somewhere that it should be 2 pints per minute. The reason is that the level in the float chamber's sight on the U-tube is sinking too low at higher RPMs.

I’m currently filing a thick flange gasket out of 1/3-inch Pertinax. The temperature figures showed from Don S. elsewhere are worrying me; a cool carburetor is a good carburetor.
However, this modification isn't related to the root cause of the mixture running too lean when the engine gets hot. That’s a problem that has gradually crept in—after all, the engine used to run perfectly without any changes.

Thanks again to everyone for the good helpin'. My thinking has shifted from "air leak" to "insufficient fuel supply."
 
Big hammer said:
Lowering the coolant temperature might help , 200 degrees F is a little high for my liking. 50/50 mix of antifreeze will ran hotter than water + water wetter by 30-40 degrees F . 20/80 mix of antifreeze will run cooler than 50/50 , some makers of water wetter say add to antifreeze will also run cooler ( I’ve not experimented with that) 1000 miles on a rebuilt engine it may need more break in time ?!
Click to expand...

So you are suggesting my engine will run at 130-135°F if I remove the anti-freeze?? I run Peak green cap 50/50 and my engine runs at 170-175°.
 
Do you have a thermostat ? Sounds like you don’t need too do anything 170-175 *F is perfect ! Yes water + water wetter your engine will run 30-40 *F cooler !! I’ve done this with my A and an modern car . The A was running at 200*F and I flushed the system and ran water + water wetter and dropped the temperature 30-40 * using an IR hand gauge. With the modern the temperature ran at 194*F for 10 years by the dash gauge. It started running much hotter in stop and go traffic , so I flushed the system with Pestone super flush following the instructions on the bottle ! I then used water + water wetter and drove the same roads to and from work watching the dash gauge. It didn’t go over 160*F , the outside temperature had cooled down some , the car ran crappy and used more gas until I changed back to a 50/50 mix of antifreeze , it then ran at it’s normal from day one temperature of 194*F !

If you all don’t believe me, drain and save your antifreeze, flush with water and or flushing chemicals made for cooling systems , following the instructions on the packaging, and for another 15$ use water +water wetter , you’ll see for yourself the water is a better coolant than antifreeze , question for you if antifreeze is such a good coolant then why do we not use 100 % antifreeze , don’t do it or you will overheat your engine !! Also 100% antifreeze at a higher temperature than 60/40 as stated on the container.
 
Werner,
Your running Avgas 102 concerns me. Am I correct in that the octane level of that fuel is indeed 102?
High octane fuel is in my understanding is formulated to be more difficult to ignite than the lower octane fuels preventing the fuel from igniting before the spark actually takes place in high compression engines.
Model A’s are plenty happy running on 87 octane fuels.
I would suggest that you drain the high octagon out and replace it with an 87 octagon fuel and test drive it with that before spending the money on a new carburetor.
 
 
Problem found!
The engine was running too lean under load because the installed housing gasket was too narrow along the thin section by the float chamber; when the housing halves were tightened, a tiny gap of approximately 0.008" opened up, allowing air to leak in.

Now the Ford engine is running smoothly again, just as it should.

But: A devil curse on the manufacturer of that stupid gasket! -


P. S.: While I was at it, I insulated the flange joint with a 0.35-inch-thick Pertinax gasket.
 

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1crosscut said:
Werner,
Your running Avgas 102 concerns me. Am I correct in that the octane level of that fuel is indeed 102?
High octane fuel is in my understanding is formulated to be more difficult to ignite than the lower octane fuels preventing the fuel from igniting before the spark actually takes place in high compression engines.
Model A’s are plenty happy running on 87 octane fuels.
I would suggest that you drain the high octagon out and replace it with an 87 octagon fuel and test drive it with that before spending the money on a new carburetor.[/QUOTE


Dear Dave,

You’re right that "Ultimate 102" has such a high octane rating. However, that isn't the reason I use it exclusively; rather, it’s the only gasoline that contains no alcohol or ethanol. At €2.50 per liter, it is more expensive than fuel containing alcohol.

But alcohol-blended fuel makes the engine run roughly and damages gasket materials and Zn.

"Avgas" planefuel is a different type of fuel. It also contains no alcohol but is leaded. Something piston-driven aircraft engines require it.
I really like using it because it results in very smooth combustion. However, using it in cars is prohibited in Germany—though that doesn't bother me—but with the current price of over €2.75 per 1 liter and the difficulty of sourcing it, it’s no longer a favorite of mine.

Of course, the A-engine doesn't care about the octane rating. High-octane fuels contain ignition accelerators—more in winter than in summer.

P. S.: "Your" ex engine in our Little Green Roadster is now a perfect engine again!
Click to expand...
 
Werner said:
Problem found!
The engine was running too lean under load because the installed housing gasket was too narrow along the thin section by the float chamber; when the housing halves were tightened, a tiny gap of approximately 0.008" opened up, allowing air to leak in.
Click to expand...

Good sleuthing!
 
Werner, in the California, only gas with alcohol is available for cars. I use Marvel Mystery Oil, in my fuel tank. I don't know the fuel chemistry, but Fuel with alcohol in it is called a "dry" gas. Without alcohol, the gas is "wetter' gas, not sure what all that means, but the MMO works great for me, don't know if it available in Germany. Even in our hot weather, never had vapor lock.
 
HC in California,


what you are written is correct. If the fuel contains a little bit mineral oil, the flame front propagates slightly more slowly upon ignition. This ensures the piston exerts pressure on the crankshaft smoothly and evenly, rather than with a sudden, jarring impact.
Theoretically, synthetic oil can yield a bit more power because these oils contain an extra oxygen atom.
I’ve been using MMO for 15 years, though unfortunately, it hasn't been available in the EU for about three years now. MMO is a simple mineralic white oil with a very low viscosity, containing kerosene as a solvent and added detergents.
You can simply put it into the tank or add it using the more complex Marvel Oiler system. I need this tool!
 

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