Re: Engine melt down
I had the same experience just a year ago. the #4 piston on a newly rebuilt engine dramatically melted while I was cruising at about 50. The other three were also on the way to melting. Fortunately no damage was done to rods, mains, and valves. I posted on fordbarn to see if others had experience the same. At the time nobody had. Several people suggested I didn't know how to drive a Model A.
Since then there have been several posts on fordbarn about engine failure with the #4 melting.
My failed engine was returned to the builder. It was re-bored and new pistons installed. it was never determined what caused the failure. The builder felt he had allowed adequate piston clearance. What stands out though is that a number of the major suppliers had recently started stocking pistons from Taiwan instead of from US mfg Silv-O-lite that they had been selling before. The Silv-O-lite's are more expensive. My engine had the Taiwan pistons in it from one of these suppliers.
When the engine was rebuilt I insisted on Silv-O-lites. The engine has been returned and has been in an engine test stand for the past several months and has about five hours on it at various rpm's. The test stand is instrumented with water temp. exhaust gas (EGT), tachometer, gauges, and a running time meter.
On the test stand at 2,000 RPM with the GAV open one turn the EGT is 800, with the GAV closed 900. In a discussion with Silv-O-lie they said aluminum melts at 1220, however, the piston normally does not see as high a heat as the EGT reading due to the fuel and air coming in on it.
The engine is performing well in the test stand. I can only surmise the failure was due to the quality of the pistons.
Tom Endy
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