A while back I had a merc crank ground and at the time I bought bearings for the mains.. My question is will these bearings fit an 48 and earlier block? Are they the same? As for an 8ba? Sent from my iPhone using H.A.M.B.
For '39-48 block with Merc crank you need 8BA mains. The rear one is a bit different on the crank side. The good floater rod bearings will be good to go on the Merc crank. (edit...both type rear mains will fit either block, BUT the rear main bearing surface on late crank is slightly shorter than 59A...and fits the late bearing, of course.)
Front and center main bearings are the same from 1939 through 1953. The rear main bearing is different. You can see the difference by the width of the locking tang (the part of the bearing shell that fits into a notch machined into the block).
Match the main bearings to the block. In other words, any 49-53 flathead block should be fitted with the 8BA type main bearings. The 39-48 blocks would get the corresponding main bearings (which have the 81A prefix on the factory part number). You can install the 49-53 Mercury crankshaft into the 39-48 block, but as stated above, you will have to use the 39-48 main bearings. It’s generally recommended that you should use the 8BA type rods along with the 49-53 Mercury crankshaft (and the 8BA type rod bearings).
Mac, hopefully I've made the right decision to go with full floating rod bearings for my motor with this same combination ('48 Ford 59AB motor/4" Merc crank). I had read where those bearings were superior to later versions.
Full floater bearings were even installed in engines that didn't originally come with them, for performance purposes. I've read of race hemi engines having full floaters used. No idea what they found those bearings from though. I do know it takes much more care to correctly clearance and assemble full floater bearings than just snapping in some tanged insert bearings. Take your time.
floaters were used in about all flathead race motors. Early OHV's were rod tossers once they were souped up and turned too fast, So Moon offered floater kits to eliminate one of the main problems that destroy rods at high RPM. From what I have found out so far ( a rather poor HRM article and oldish Moon catalogs) they used Ford stuff if dimensions of engine were in range with lots of machine work, and Moon supplied larger floater bearings that I assume were special made. They noted Packard, Chrysler, and others in the catalog on the big ones. AND...to use '49 up crank in '39-48, you will need '49-53 main bearing. Block fit is the same, but late crank has a shorter space on the bearing area and thicker cheeks on the bearing take up the slack.
Also have a 1CM cam. Would this work in the earlier block? Timing gear? Any modifications needed. Sent from my iPhone using H.A.M.B.
It will fit but you'll have to figure out a good ignition to fit the late front cover. Normal gearing is the late type with this but there are builders that prefer thrust against the block on all. Mercury used the early gears for a while and then switched to the late gear on later '49's!
Also...remember that the engine will be significantly shorter with early cam and water pumps, '42 distributor if you are putting this into an early car.
Another cam I have is marked 59 so aguess will use it with the crab distributor Sent from my iPhone using H.A.M.B.
Hi Bruce First excuse my english i'm french, i hope you can help me I have a French flathead (39 / 48 specs) and I want to put a Scat crankshaft (49 up crank). To put 49-53 main bearing i need to machine to reduce the thickness of the block of arround 0.0287 inch does that seem normal to you Thanks
Hello Roy , I think Bruce posted that the block dimension was the same,,,it’s the crank that is somewhat different . Use 49-53 bearings for a 49-53 crank,,,,no matter on the block . The French blocks should be the same 39-48 specs,,,,as the Ford original spec . Good luck,,,,,it should run great . Tommy
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