1946-1948 Ford Flat Head ID and More

Just recently picked up an ole flat head and before i can tear it down it's gunna take some mystery oil to free it up and probably a bit more. but while the cylinders soak up a bit heres some information on it. The pistons all have 3.060 cast into them and not sure if theyre stock or an over bore since some web sites have much lager pistons theyre selling saying their stock? about half of the valves have been changed over to stainless, valve measures 1.508. The bads are the motor got put off to the side for many years and shes a bit froze up.

from the water jackets on the block it id's as a 1946-1948 239CID 100HP motor, but the casting numbers into the bell housing don't seem to match up with anything I've been able to find. the top number looks to be 0564 or possibly C564 its hard to tell on the 0 just cause of flashing, the large number underneath that is 59.

So far there appears to be no cracks in the block in the usual spots but will need to get it unlocked to get a much better inspection prior to sending it out to get hot tanked and probably the buddies machine shop to clean up the deck a bit even though it looks like it was machined before i wont know for certain until i can get the pistons out and measure it. after all said n done then i'll finally get to rebuild it.

Any help or advice from someone with some flat head experience would be great. i do have some resources up here when it comes to flat head tech but it's sometimes hard to get ahold of em and would like to start writing down any information i can get in the mean time. I'll get some pics up soon of what im starting with.

Thanks,
-T

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Heres some pics of the Cast Numbers and the numbers stamped into the intake pad by the bellhousing and a pic showing the water ports location and style. so far the internet has been not much of a help


Attachment 52935Attachment 52936Attachment 52937

ok so i figured out most of it after some more scrubbin, the full stamp looks to be *99A834II3* which is 46' 69A ford or merc wont know more til i open it up, but the serial number looks from what i have found to be a restamp of what would have been *99A834113* however the block casting C564 does not show up anywhere i can find. C from some sources says Canada, but 564 is not one of the numbers.

Also the 99A in the serial says its a 69A motor, but the block clearly says 59 in a nice big stamp right on the bell housing? this is throwin me off and to boot the serial location is not following anything i can find as far as resources go either. every web site says the same thing, "serial number is not on the engine itself" but on mine it's right on the rear of where the intake mounts on the top of the block.

any ideas or help would be appreciated.

OSK/T

If indeed the pistons are 3.062" diameter (3 1/16") and the date of the serial number is for a '46 the block may be a "carry-over" engine from 1941. The reason there are no Fords/Mercurys from 1943-1945 was because Ford Motor Co. was making jeeps and other WWII machines. Ford often carried over parts left over from a previous year to the next year where possible. The 1941 Mercury blocks were 3 3/16" bore V8s compared to the Ford 3 1/16" in 1941 but after WWII the same block was used for Ford and Mercury from 1946-1948 with 3 3/16" bore and 3.75" stroke. If your pistons are 3.062" for 3.0625" bore that means your block has not been overbored and that is good since overboring usually leads to an engine which will overheat! My guess (which may not be correct) is that your block is a carry-over 1941 Canadian Meteor block if indeed it is of 1946 Canadian origin. If this block is cleaned up and found to be free of cracks it is a gem! Just put a 3/4 cam in it maybe a dual carb manifold and look around for a 4" Mercury stroker crank in it (1949-1951 Mercury). I have one for sale but by the time I box it up and freight it you might be better off to look at a stroker crank from Speedway Motors in Lincoln Nebraska. Other good news is that there are already shallow relief cutouts in the block between the valves and the bore which could be enlarged with a grinder for a little better breathing but overall don't expect to get more than 150 HP out of it with a reasonable possibility of only 120 HP even with those beautiful (but now expensive) finned aluminum higher compression heads. In the 1950s a 120 HP flathead with a 3.78 rear would have been considered "a warmed over" street rod. Still the low gear acceleration was pretty dramatic up to about 40 mph with just a standard 3.78 rear and better with a 4.11 ratio rear.

Best Wishes,
Don Shillady
Retired Scientist/Teen Rodder

For more information on your engine go to the following web sites that specialize in flatheads.
Early Ford V-8 Club
Ford Barn

They can answer all your questions. Looks like you have a great rebuilder there.

Could be a CMP (Canadian Military Pattern) engine from an Army truck. Ford of Canada was fond of that type of relieving the block, not so much for extra breathing but because they believed the thick metal there in the original casting led to heat cracks. They may have been right, we have several of these blocks and none are cracked! I can't see any of the typical cracks in your pics, either. Usually they are between the center water hole and the bolt holes nearest them. They don't matter much, but it's nice to see one without those cracks, since that is the first place they crack.