Hard to start flathead

rbassemir

rbassemir

Member
I have what I believe is a 1938 flathead in a 1935 Ford Convertible Sedan. It used to start pretty reliably even if it sat for a couple of months but that has changed and I'm looking for suggestions for things to check. Here are the symptoms:

It started up on Mother's Day and we took a ride down the street. After going less than a mile, it stopped and would not start again. I was low on gas, so I added some more to be sure I was not out of gas. It would crank but would not start. I checked for a spark with one of those in line spark plug testers and saw a spark. I pulled a plug and it appeared to by dry. I sprayed some starting fluid and it did not even sputter. I towed it back to the shop.

In the shop I checked voltages and found I was getting 4.5 volts at the Battery side of the ignition coil. I disconnected the fuel line and cranked the engine to be sure the fuel pump was working. It was. I could not see any gas in the carb when I pumped the pedal. I suspected it was a carb issue.

I pulled the carb and there was a fair amount of dirt in the bowl. Went through the entire disassembly and reassembly of the carb cleaning a blowing out all orifices. Put it back on and the car started. I thought I solved the problem.

The next day I could not get it started again. Same symptoms but this time I can see gas being squirted in the carb when the pedal is pumped. After multiple attempts I had to put the battery back on the charger. Later that day is started on the first attempt. It seems to have a mind of its own. I periodically try to start it. Sometimes it starts and sometimes it just cranks. I have not yet found any pattern to the problem.

I have 6.2 volts at my battery, but under the dash it is down to 6.0 volts and on the output side of the ignition switch it drops to 5.8 volts. Through the ignition resistor and I end up with 4.5 volts at the coil. I don't like that but maybe that is not a problem.

I have not pulled the distributor cap or checked the points. Since starting fluid does not seem to get the engine to even pop, I am thinking I have a weak spark? My ignition line does go through a resistor which accounts for less than 6 volts at the coil. Could the capacitor be the issue?

This is my first flathead and have ever tried to do any ignition timing. I have not changed the plugs or wires since I purchased the car. It used to be fairly reliable, but lately I have lost confidence in its reliability.

I would prefer to stay with a 6 volt setup but if going to a 12 volt setup is going to make the car more reliable, I would do it.

Your comments / suggestions are welcome.
 

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If the car has been sitting in damp ,remove distributor and with out disturbing any of the settings (as a interim fix ) sand the points with 60 grit paper ,tear of a small piece and fold it back on its self .knock out the caps through the coil hole ,clean all connections ect condenser. piggy back another condenser with alligator clips , by pass the resistor with a jump wire as test, refresh the battery cables with a length of heavy welding cable ,jump 12 volt one to the starter and one to a head bolt ,key on ,you get a few sparkes ,
 
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No ,some points get a crusty build up this is the best way to cut through it while they are in the distributor ,you could use a points file also .The slight roughness on the points can be a benefit for these cars that sit around , the long term goal is maybe send it to be set up on a machine. Check the gap that its opening also .Ted
 
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I had a Ford 170 six cylinder that did that same thing. Different weather conditions affected it. Replaced cap & wires, cleaned all ground conections and never had the problem again.
 
This is just a "for what its worth" because there is a lot of great discussion here on this topic but I will tell you my experience with my '38 flathead. I have had is since about 1972. Engine was just worn out when Grandpa gave it to me. Dad bought a running engine for $50 and put it in. I could start it but it took a LOT of effort, sometimes only by dragging it with the pickup. Fast forward 20 years. I got serious and had the "original" worn out engine rebuilt. Still hard to start. Bought rebuild kits for distributor and carb. Better but not good. Bought a rebuilt carb. Still a total pain to get it going but it ran well once it started. Tired of this so bought an electronic ignition distributor. Better but still not good. There was always rust in the gas so I bought a NEW carb and gas tank. That was it. Now I hit the starter button and I swear the engine does not make a full revolution before its fired up, every time. Finally! I know the dist is a debated issue but I just love mine...
 
The fact that it would not try to start on starting fluid tells you fuel is not the problem. You have voltage to the coil so that's not it. Most likely it's the coil, points or condenser. The problem with the spark testers is you might see a small spark but that does not mean its capable of lighting the mixture. The spark might not last long enough to ignite the fuel molecules between the plug electrodes. The conditions in the cylinder such as compression and air fuel ratio effect the voltage needed to jump the plug gap. The spark you see on the tester might not be the same quality of spark that happens inside the cylinder. If its big blue snapping spark it's probably good but if it just a little static electricity type of spark that might not get the job done

We always had cars with points growing up and my dad was in the Model A Club. Every car he owned, collectible or daily driver always had points file in the trunk, and those files got us going more than once. If you're doing proper maintenance the points should be replaced before they ever get that bad. Condensers do go bad but not nearly as often as points. There is always a good chance with a coil that old the insulation is breaking down inside. caps also crack...

Your car worked all these years on 6-volts so there is no reason to change it to 12-volts. I was a fleet mechanic when 75% of our 400 vehicles still had points. They were all 12-volts, and their points, condensers and coils failed too. 12-volts does not change the fact that points have a service life and need to be replaced. The condensers should be replaced too. Coils last for years and years but at some point, they also fail. If I owned a car with an 88-year-old coil I wouldn't trust it. Yank the distributer and if the bushings are good replace the points and condenser yourself with quality parts and send the coil out to have it rebuilt. Then pick yourself up a spare working distributer and the tools to replace it and stick it in the trunk. Make sure your fuel system is clean and then you can confidently drive it all over the place.
 
I appreciate all the feedback. I pulled the distributor cap and it shows lots of wear inside. I ordered a new cap, rotor, condenser and figured I would put in new plugs also. I filed the points with a point file. It is hard to see the points well, but from what I could see, they did not look bad.

When I rebuilt the carb, there was rust in the bowl. The gas tank was replaced by the previous owner and looks clean inside. I'll pull the glass bowl and check for rust in there. Maybe add an inline filter.

I'll post up later to let you all know what happens.
 
Update:
I put in new distributor cap, rotor, condenser, spark plugs. I used an ignition file to lightly file the points. Added a temp gas filter to be sure I am not sucking up rust from the tank / fuel lines. Gas coming in is clear. Once there was gas back in the bowl, it fired back up.

An hour later (engine still warm) it would not start.

Now I think I might be flooding the engine. I have used the choke every time I try to start it.

Now I have been attempting starts with no choke. So far, every attempt and the car is starting on the first couple of cranks.
 
Try jumping the ignition resistor. I had one that would fail intermittantly and had a hard time trying to fix the issue.
 
Now that mine is finally an easy starter, I have to leave my foot off the gas when starting and no choke. It seems these flood easily. My old carb would drown the engine with the accelerator pump which probably just needed to be adjusted way down. If it hasnt been run in a while maybe a little pedal but absolutely no pumping it!
 
If you think it's flooded, hold the gas pedal to the floor while you're cranking the engine. That gives the engine extra air to evaporate the flooded fuel that is laying inside the intake and cylinders, and it should start in a few revolutions depending on how flooded it is. You should not need to use the choke to start an engine that is warm. Each engine is a little different, it might need a pump of the pedal to give it a squirt of fuel or the pedal pushed just a little bit to open the throttle plate to give it more air. Every time you push that pedal you are giving it a squirt of fuel If its flooded you do not want to keep pushing the gas pedal, only once to hold it to the floor until it starts.

If it is flooding after it warms up, it could be because an engine gets hotter after it is shut off, this is called a "hot soak". The fan is not blowing air
through the radiator and over the engine. The coolant is not taking the heat away to the radiator. For a brief time, the engine gets hotter than when it was running. If the float level in the carburetor is too high the heat will expand the fuel and push it out of the float bowl and into the engine, flooding the engine. Also, if the power valve is leaking, it will drain the float bowl and flood the engine. If the engine sits long enough eventually that fuel will evaporate and the engine will no longer be flooded but because the fuel has leaked out of the float bowl, there is no gas to start it until the engine has cranked enough for the fuel pump to fill the float bowl back up.

Next time you drive it and get it warm. remove the air cleaner. Put something on the gas pedal to hold the throttle open so you can see inside the carb all the way down to the intake. If it is flooding, you should see fuel dripping out of the carburetor and into the intake.

Never crank a starter for more than 15-seconds. The armature can get so hot it can melt the solder. Crank it for fifteen seconds and then let it rest and cool for 15-seconds. If an engine does start in a couple of those 15-second cranks its usually not going to start unless it is flooded. If you're not at home, you need to stop cranking and figure out the problem before you drain the battery and then you are really stuck. Always carry a long wire with alligator clips in your vehicle so you can bypass stuff like ignition switches and resistors or even jump power from the battery to the coil.
 
More good suggestions. You folks are a wealth of information. I appreciate all the input.

Another "hint" as to what might be going on is that the spark plugs I took out were black. Not oily black, but like black carbon. With the new plugs in and only run for a few minutes, they too turned black. I guess one calls it carbon fouled.

I think this could be caused by a rich fuel mixture. I will also read up on the steps to adjust the carb.
 
When the engine stopped, did it sputter or just quit like turning-off a light switch? If it was the latter, I would suspect you have an electrical issue. I may have missed it, but did you change out the coil?
 
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