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Joe K · 01-31-2019, 01:50 PM

Insert bearings are at their best when used with pressurized lubrication. Babbitt bearings CAN be configured for PL, but were not done so with Ford - and most since then perhaps even less.

A rebuilt Sears engine of my experience which was rebabbited without oil grooves comes to mind.

One thing which Ford did on the original engines was "superfinish" the cranks. My experience with modern crank grinders is they're working to surface roughness standards which have been common since the rise of PL.

In PL, the crank journal rarely if ever actually touches the bearing. So there is no real need for superfinish. In a babbit bearing engine it does matter - and hence the need for superfinishing. Were more crank grinders capable of superfinish is my lament.

I once asked my Model A mentor what one could expect for engine life of a "standard" Model A engine. His reply "60K miles if all attended to in timely manner." He was a professional restorer of some minor note in Central Massachusetts. And he didn't specify superfinishing as a constructive option as in the 1980s few had even given it a thought.

I myself had a 26K mile AA chassis which was used as a portable platform for an industrial welder. Purportedly (according to the original owner) that engine had never had the shims changed. It still ran, was horribly loose, but seller and I did get it up to 40 mph in a test run. (no floorboards!) Perhaps the difference in soldiering on in this original engine is in the original superfinishing?

Well, it (the 1930s) was a different age. So one then expected the cars would continue to soldier on for 80 years.

Joe K

01-31-2019, 01:50 PM	#10
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Babbitt Insert bearings are at their best when used with pressurized lubrication. Babbitt bearings CAN be configured for PL, but were not done so with Ford - and most since then perhaps even less. A rebuilt Sears engine of my experience which was rebabbited without oil grooves comes to mind. One thing which Ford did on the original engines was "superfinish" the cranks. My experience with modern crank grinders is they're working to surface roughness standards which have been common since the rise of PL. In PL, the crank journal rarely if ever actually touches the bearing. So there is no real need for superfinish. In a babbit bearing engine it does matter - and hence the need for superfinishing. Were more crank grinders capable of superfinish is my lament. I once asked my Model A mentor what one could expect for engine life of a "standard" Model A engine. His reply "60K miles if all attended to in timely manner." He was a professional restorer of some minor note in Central Massachusetts. And he didn't specify superfinishing as a constructive option as in the 1980s few had even given it a thought. I myself had a 26K mile AA chassis which was used as a portable platform for an industrial welder. Purportedly (according to the original owner) that engine had never had the shims changed. It still ran, was horribly loose, but seller and I did get it up to 40 mph in a test run. (no floorboards!) Perhaps the difference in soldiering on in this original engine is in the original superfinishing? Well, it (the 1930s) was a different age. So one then expected the cars would continue to soldier on for 80 years. Joe K __________________ Shudda kept the horse.