I am having an issue with my Flathead in my truck. It is ok for a while depending upon how hot it is outside for some reason. But the thing is after a while of driving it starts to break up spitting and sputtering. I am a little lost I have checked the fuel filter and it seems to be okay I can see in it and it is not clogged. The other thing is points but won't points be shitty from the get go? or another thing my friend brought to my attention is the fuel tank only has a tiny whole in the gas cap for pressure to be released. He thinks maybe a vent will help out release pressure in case it is built up to much and is forcing to much gas.
not much to go on but my first guess would be a bad coil. as for the tank, too small a vent will cause fuel starvation, not excessive pressure
Could be vapor lock. The road is hot, the gas now has too much ethanol and it boils. Put an electric fuel pump on near the tank. Insulate your gas lines.
I had constant problems like this once. The car would start up, idle and run fine but after a number of miles it would start to conk out and be intermittent. I couldn't see anything wrong with the fuel system or pump, points and coil were fine. It turned out to be a faulty condensor. For the £5 it costs you might as well try another one.
The fuel tank doesn't build up too much pressure it creates a vacuum on the cap side and the pump can't pull the fuel out of it. it should probably have a vented cap. My first thought is that it is getting warm. What temp is it running at when it starts to act up? I don't think it will make any difference but you may look at changing the condesnor. You may also lay your hand on the coil. A couple of years back I had valve in head that started acting up after it ran for a bit. The coild was getting hotter than a 2 dollar pistol. When I OHMed it out cold it was an open circuit and when hot it was open in one direction and closed in the other. For all intents and purposes it was turning into a doide when it was hot. Changed the coil problem solved.
Thanks guys I forgot to mention I do have an electric fuel pump near the tank. But I will try the condenser and post the results.
I did notice that the coil felt real hot. But I am still learning so thanks I will change the coil out as well
Don't ever change two easy things at once...that way lies madness. I would buy both, as condenser is cheap and I think coils is first suspect in line. Change coils, runnit, if still bad toss in condenser. If worried about cap, make the run without it, put it back on if car doesn't flame out on the test drive and await developments.
A true "shadetree mechanic," ...yeah that's the way we did it back in the day, before cheap digital testers and such...never change more than one thing at a time!
Coils and condensers are a testing problem, as the bad ones are often fine when they are cold. Low buck way is to borrow one from a car that runs... There are different Mfd values of condensers and wrong one can cause trouble over time, but as a rule of thumb for a road-test, just about any automotive condenser that works will work on nearly anything for a test.
Also if your point gap is too close from the get go they won't work very well after they heat up. Hope you didn't foul a set of plugs running in a missing condition.
Is there a resistor in front of the coil to take the heat? That is if you didn't get the replacement coil with built-in resistance. Never hurts to have redundance anyway. Also the replacement dual points I bought (for my crab distributors) from India were crap, no spring tension, mismatched surfaces. Clean-up and re-use old ones for dependability.
The Jalopy Journal
