The 3 changes in the FORD 'A' engine "28-31

[SHELBY MESSER]

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I use to know what the 3 changes that were made in the model 'A' engine. The only one I think I remember is a change in the rear main bearing oil flow. That may not be it. I don't want to stir any one wrong. But to the best of my knowledge there were 3 major changes. Anyone have any info on this. If you plan to build an engine this my be helpful to know. I have an early '31 engine I'm planning to build and put in my late '31. Talk about these new ' A' engines, They haven't proven themselfs yet. This engine has proven it's 85 yrs.and still running (well I pulled it from the original car(e'31 coupe) that I posted picture earlier. I'll have to do a major-major rebuild. It would run but not that great. I sold him a factory I had for $500. The I had with this fac. rb. was some times it would start right up. Other times I would run down the battery, and hand crank maybe 1/2 hr. before it would crank( the last time was in front of a local FORD dealer show room.) I had a good '30 engine engine that would in the first or second turn every time. Using the same carb. and distr. Something to read and enjoy Shelby, Sacramento.

[Hayslip]

The early engine had 5 camshaft bearings later reduced to 3.

[Brady]

Later blocks were drilled with oil access hole to the rear camshaft bearing

[ModelAkid]

Later blocks had more stiffeners or braces cast in the block above the rear main.
Another difference is another hole for water circulation was added in the middle, with the head changed to match.
Also - this is not blocks - but there are 4 or 5 different types of oil pans.

[Stakebed]

didnt the rear main cap drain pipe change diameters too?