Is there a diamond 81A flathead and a regular 81A?

Jason in TX

Jason in TX

Well-known member
I've got a flathead from a 1940 Ford. "A" marked on the heads. Diver's helmet distributor. 24 studs.. yada yada. 81A

I noticed a diamond cast into the flat area above the passenger side water pump. I know in Model A 4 cyl world, a diamond block meant a replacement block that some consider to have more thickness.

I was wondering if by 1940, they were just casting these on all the blocks, or if this is some kind of replacement/rebuild/industrial/etc. block

Thanks for your help!

Jason
 
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Jason, i have an 81A block that has the diamond in the same area as yours, but mine is not a stamping, its cast as part of the block, I think the diamond was the ID mark of the plant were the block was casted. I am sure Bruce Lancaster will chime in on this.....Ed
 
34fivewindow said:
Jason, i have an 81A block that has the diamond in the same area as yours, but mine is not a stamping, its cast as part of the block, I think the diamond was the ID mark of the plant were the block was casted. I am sure Bruce Lancaster will chime in on this.....Ed
Click to expand...

I posted this about five years ago. No one seemed to have any idea what it represented. I have three '37 blocks, two with the diamond cast just fwd of the right cyl head and one without it. I also have a 1941 block with the diamond cast into the sludge trap in the lifter valley. I've seen the same diamond in several 59A blocks, in the lifter valley, I had over the years. I would be curious what they mean, too.
 
OOps. Yeah. Mine is cast as well. I said it correctly in the first sentence but then I goofed on the second one... I'll correct it above.

Perhaps A replacement blocks were the beginning of the new plant where Henry started getting his engines made and subsequently later blocks received the same diamond due to them also being made there.

Anyone else have a comment on the diamond cast into the block on the front passenger side?
 
A diamond is a guys best friend. I have a Model B diamond engine in my Model A, never noticed it was a diamond untill Paul's eyes went right to it. lol Walt
 
"Secrets" published a pic of a 59 with a diamond somewhere around the water drain valve hole. I've never really looked to see if I have any V diamonds...all of my B's seem to be diamonds, though, from the late '30's.
I would have to assume since the complete engines were built and serialed by Ford that the diamond bangers were cast in some Ford foundry and that the diamond either identified the particular plant or meant something in the Ford system.
Flatheads in general carried very few cast identifications...witness all the "what year is this thing" letters on here!
One thing from parts history: I do not think that an 81 type block is at all likely to be a later-than-production years casting because after WWII Ford discontinued that block and replaced it with the 41A, a purely replacement part that was a 59 block cast with smaller barrels for all 221 replacements. That pretty much says that early blocks were not made after the war, I think. I'm pretty sure that 59 blocks and complete engines were made after 1948 and that those came through with the cheaper 8BA internals. I think in general that flathead blocks including 59's that were made with lots of cast numbers and letters on bellhousing were likely replacement blocks not installed in production vehicles.
The 41A did not last long as the 59 kind of became the generally used replacement for everything early.
 
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