If you read the last story about the adventures with the Model A Fords you know that we own a 1928 Model A pickup truck. We bought the truck several years ago and always have fun with it.
Just after it became a part of our family, the engine timing seemed a little slow and it was losing power. Son-in-law Mel and his son David were at our house and both are experienced mechanics, so we decided to reset the engine timing.
A Little Mechanical Insight
For you mechanics, the distributor on the Model A Engine is a manual timing advance by using a lever mounted by the steering wheel. The distributor is located on top of the engine (easily accessible) and the timing is adjusted by loosening the distributor cam and rotating it forward or back to set the timing slower or faster. The rotor turns counter-clockwise.
On With the Story…
Mel and David were doing the engine work and were ready to make the timing adjustment. They asked me which way the rotor turned when the engine was running and I said counter-clockwise – but they didn’t hear the word “counter” and made the slight adjustment in the wrong direction. None of us realized that error at the time.The other distributor parts were replaced in position and we were ready to start the engine – but it was far too slow in time.
When I turned on the ignition and hit the starter there was a VERY LOUD BANG!!!
The muffler was blown entirely off the truck and skidded across the driveway, the internal baffles from the muffler were blown out and skidded across the garage floor near my wife who had been sitting there reading a book. That caused her to nearly faint and my daughter (Mel’s wife) missed all the fun as she had gone inside.
What Was That?
Mel and David thought they had ruined the Model A engine and I was also alarmed at first – then I realized what had happened. That is not an uncommon experience with a Model A Ford. When the timing is off, unburned gasoline vapors will pass through the engine into the muffler and then are ignited inside the muffler when the ignition fires and an exhaust valve is still open. In this case, the round muffler was blown almost entirely flat and completely off the car.
The only real casualty was a muffler that was destroyed and required replacement – but I had an extra muffler in my parts inventory that I had found at a swap meet. All is well and no one was hurt – and we all had a good laugh.
More Model A Stories:
From the Model A Archives: The B.T. Incident
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