Technical 81A Flathead ID help

I bought this saturday, it was advertised as a mercury engine on CL. I'm not convinced its a mercury, but it appears to be a good engine. I did not pull heads or pan, yea i know, never buy unless blah blah...... it just wasn't in the cards.

Anyway I'm looking for help on some things that dont make sense to me. The guy said it came out of 46 truck. But he also said it was a mercury and at one point he said it was an industrial engine, so who knows. It has a strange looking dist/mag thing on it, and it doesnt have dual belt pulleys. Theres no 59 on the block any where, but there is the number 10 on top of the bellhousing. Date code is not visible at this point, it covered with thick paint. Heads have numbers 81A-6050A on both heads towards the front. The fan mounts on the generator also. He took the truck and made some 4x4 Frankenstein thing with it. His dad took this flathead fixed a valve and got it running. And he would run it on a stand they had made.
The engine turns over and has all the fixins.

Just looking for some more lnfo. Any help appreciated. Thanks.

Here it is.

 

My book says 81A is a 1938 90HP

 

Cool, thanks.
Here is the block where the date code is supposed to be.

 

Mercury would have 99T on the heads. The Merc engine was offered as an option in 1 ton and larger trucks listed at 95 HP. The 81A came out in mid-year '38 (early '38s had the 21 stud '37 engines) and was used until supplanted by the 59 series flatheads in '46.

 

The engine you have is 1939 or 1940 probably a 3-1/16 bore pulling the heads will tell for sure you might find the cylinders are sleved which was common for that era block.

 

Hey thanks for the replies. So whats the deal with the fan mounting on the generator. I'm pretty sure thats not gonna work. What are some other options?

 

It works providing you have the room.

http://i.ebayimg.com/00/s/MTE5NVgxNjAw/z/HmMAAOSwYGFUvHfH/$_57.JPG

http://img.photobucket.com/albums/v394/NealinCA/DSCN2474.jpg

http://i37.photobucket.com/albums/e69/modelabob/29 roadster/DSC_0081.jpg

 

That is not a 39-40 motor, that is a 1938 motor. Kinda rare, but not desirable like a pre-war Mercury. That is the first run of 24 stud motors with the 36-37-38 crankshaft. If this was a 39-40 motor the crank snout would be longer. Specific identification information is in this thread: http://www.jalopyjournal.com/forum/threads/ford-flathead-block-identification.594463/

The heads on that engine are one year only due to the location of the part number markings, but offer no performance advantage. If you replace the heads with aluminum or later I would be interested in the heads from that engine. I happen to be restoring a 38 Ford.

 

Lots of good info on that link, thanks.

Will the later model heads and intakes fit on this block?

 

There are no date codes on these engines, as I assume you are finding out.

 

Yea. Do those numbers have any significance?

 

Foundry markings, might have at one time but no one knows today. Just decorations now.

 

All 38-48 24 stud heads and intakes, Ford and aftermarket, will fit on that engine with no modifications. All 49-53 heads and intakes, Ford and aftermarket, will fit on that engine with modifications.

 

if that is an 81a, it'll have 3-1/16 bore, 3-3/4 stroke and 2" rod throws. not something you'd really want to hop up. great for a restoration, though.