I built my first Flattie at age 12 with paper route money and yes my birthday and Christmas gifts were auto parts
If that is a "99", you may be able to swap it for a newer 8ba that runs . That's what was in my '41 p/u and it is an easy swap. Also, didn't Mercury start out as 239s vs. Ford at 221 ?
All of those I saw were cracked from a cylinder to the valve seat area. The only way to tell was with the heads off and a real good eye. Most had to have some rust spots but not all.
...also having a famous racing engine building uncle who told me , " Don't waste your money on a flathead you'll get nothing out of it just come over to the shop and we will throw in something worth your money ". Mind you I was 12 at the time and turned down a full race pro built engine so I can have a from the factory engine in my 34 truck . So yes I went stick with the 221 with a 97 on it ran 6v on ignition 12v on the starter and lights . I knew what I wanted and built it and NEVER regretted it . Uncle Dick was amazed and everyone loved the fact it was Old Henry Iron . If that's what he wants let him work for it and build it . It turned into a career for me and I can say I never worked a stiff job in my life . Build the Flattie !! Check out my threads and Marts also . Threads are Freddie's Latest ... and Meet Flo ! . Bored and Stroked got some real flathead science going on we grew up both flathead owners in high school . Patience is your best tool and research is your second . I mean real manuals not these glitter engine build publications , the last one I read was a fairy tale gave it to the kids to cut and paste . Any questions ask away I'll stay with this thread it's me all over again so glad to help
Fords had a smaller bore both share same rods so yes 221 for Fords bored at 3.0625 and Merc at 3.1875
One other difference, that is kind of major, the pre 48 24 stud engines had "floating " rod bearings so there is a manual fitment component in the rod to crank that is very different from the later 8ba engines. I found that was very interesting .
Equally important as magnafluxing, is a pressure test. There are a lot of places that you can't see that could be cracked. Exhaust crossover, exhaust ports to mention a few. I would never build an engine without pressure testing.
I use a mild wire wheel on my drill and clean the area between the valves and cylinders, then I inspect the area with a magnifying glass. If you find cracks between bolt holes and coolant passages, no big deal. Look closely at the pan rail and walls inside the block, that’s where they crack if the block freezes with water in it. If all that looks good, I pressure check the water passages with 20 psi for 20 minutes. If everything passes my initial checks, it goes to the machine shop for mag particle inspection.
Another Flathead concern is Core Shifting . I have yet to run into a block which suffers from this but too many Flattie owners have shared their stories even on these threads . This is when you bore the block and end up with thin cylinder wall towards bottom of cylinder . Most guys Sonic test their block * just tong the cylinders with a tiny hammer and take note of the sound changes . A short sound means thin wall are and a longer ting noise means more metal thickness . I've seen affordable Sonic Testers online if $80 to 200 is in your budget . When I buy bare blocks I tap around all over and a dull return noise means there is a substantial sized crack in that area . I use one of those women's home tool kit hammers fits in your pocket . So I don't Sonic test but do check my wall thickness and cracks at same time .
I think if you do a visual inspection after disassembly, and all looks good, have it boiled and have it magnafluxed. If that passes, your $60 acid cleaning sounds like the best engine building bargain around. Getting all the rust out of the water jackets is key to a cool running flathead. Hopefully after the acid there are no new leaks.
First picture is between 3 and 4 cyl I'm leaning across the engine so looks upside down well second picture is between cyl 1 and 2 . What do I think ? Crackle shmakle ! Flo is still making it to the test stand so we see and probably a little seepage look at the head gasket so we will experiment here on Flo how does that sound . The cracks are only a couple microns deep now and yes are known to grow in time or may seal up when warm with some Bars Leak . One guy who has seen horseless carriage days told me a little sediment in the block is good for plugging up leaks . I never forget him and sometimes I have left sediment in block if it's not overheating . Flo has been getting cleared out but I'm sure a taste of sediment will remain
This is the Down side of Head Gasket so brush is pointing at seepage area between cyl 1 and 2 so this side of gasket goes on the block
1948 Mercury in Canada and maybe Canada Does and trucks started using head bolts . I think 1948 American trucks also came with head bolts . Could be mid year you know sell the old introduce the new but in 1949 all Does Flatheads and Merc came with head bolts - 8RT , 8BA and 8CM engines . The earlier years with the studs were the 221s then 59A to 99 engines . lots of revisions cool stuff and then you have the various water pumps and bell housings it The Great Flathead Game . Neat stuff I enjoy it and am not always correct and we have different processes for each engine like in valve assemblies flywheels . I can go on but Roothawg I welcome you to the Flathead World !
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