1939 ford flat head wont fore after a rain
 

Have a 1939 ford sedan with a 46 flathead v8, seems like after a rain it just wont fire. any ideas????

Re: 1939 ford flat head wont fore after a rain
 

Since your complaint is "only" when it "rains", its not a compression issue. Now your down to spark or gas delivery issue. Have you checked at the point when this happens to see IF you're getting spark to the spark plugs??? Quickest and easiest test!! IF no spark then you have your problem area to search......... IF you have spark, then you have your problem area to search!!! Hard to answer without more information on what exactly is or is not happening and when it is or is not happening. IF it is a "spark" issue the initial point after it rains you "might" look at your distributor cap and see IF you have condensation building up from the humidity/rain.

Re: 1939 ford flat head wont fore after a rain
 

no i havent checked plugs, just seems like after a rain it wont fire, today it fired up??

Re: 1939 ford flat head wont fore after a rain
 

Hello and welcome to the forum.

Just a guess but I'd be looking for some sort of water leak that may be dripping onto the ignition leads.

Re: 1939 ford flat head wont fore after a rain
 

NEXT time it happens, pull a plug wire and spin the motor and see IF you have spark.......Then you'll know which area to start looking Again at first "blush" you're having a condensation/moisture issue inside the distributor cap would be my first look IF no spark!!!!


Does the car sit outside, or in a damp garage????

Re: 1939 ford flat head wont fore after a rain
 

Could be a cracked coil case.

Re: 1939 ford flat head wont fore after a rain
 

Even without rain getting under the hood, high humidity can condense on the spark plug wires. If they are old, the moisture can penetrate and spark will jump to ground in the wire loom instead of through the plug.

Re: 1939 ford flat head wont fore after a rain
 

What distributor/cap?

Re: 1939 ford flat head wont fore after a rain
 

I had this happen to me as well, and it was a crack in the coil tower, I only found it because it happened at night and I could see the spark "leak".

Re: 1939 ford flat head wont fore after a rain
 

Use a spray bottle mist and at night , spray the engine lightly . Have someone try starting the engine . Look for sparks , have it as dark as possible. If it starts continue checking for spark or the sound of arcing .

Re: 1939 ford flat head wont fore after a rain
 

with the engine running Spray the dist cap slowly and then move to the coil and wires my brother had a 50 ford when we were in high school (around 50 years ago )and as soon as the clouds got dark it would die then a old timer mechanic told us to try this and sure enough it needed a cap and rotor good luck