8CM to 8BA

[Ol' Ron]

the answer is quite simple. just change the parts that need to be changed. Not sure the flywheel has to be changed, but if it does just change it. I'd keep the 8BA carb and dist tho.

[rotorwrench]

The Mercury cars of the mid century era did use a different clutch than the Ford cars. They wanted one that was a bit heavier duty than the 9.5-inch Long type so they used the Borg & Beck 10-inch. It has an evenly spaced bolt pattern like the later diaphragm type clutches. The 49 & 50 were the same with the 1 3/8-inch 10-spline type input and sometime in early 1951 around February or so, they changed to a different transmission & bell housing set up. The later 1951 transmission is more like the earlier Ford types with the narrow 4-bolt pattern, diamond cut gears, and a 1-inch 10-spline input pinion. The clutch was still Borg & Beck but was changed for the smaller spline & new style throw out bearing.

Early 1951 Mercs were same as 49 & 50 but the later 51 Mercs were different. The bell housing is a larger cast iron unit but still had the rotating fork equalizer set up for the clutch. In 1952, the Mercs used the same transmission & bell housing as the 52 Ford cars since both made further update changes for commonality.

The Mercury 885 Holley carb would be out of place in a Ford car application but it is a decent carb for a Mercury application. It has a bit larger CFM rating than the Ford 8BA type. The 8BA type is easier to work on and the carb kits are less problem to get a good one. If a person changes away from an OEM Holley type then the ignition has to be changed as well since they are matched as the Holley Load-O-Matic system. Use either the 8BA with all its components or use the 885 but don't try to mix & match. There are slight differences that might cause problems.

[Solo_909]

Okay for future reference here’s a list of everything that needed to be swapped over. Fairly simple stuff. Thanks fo all the help guys.

Heads, Intake, carb, Oil pan, oil pickup, oil filter, crank pulley, crank extender, water pumps, flywheel, clutch, and bell housing.

[tubman]

That list may be OK if you want to make your 8BA LOOK like an 8CM, but again, using the 8CM heads will cut compression from an already low 6.8:1, and combined with the larger (and rarer and harder to work on Merc carb), may cause performance problems. Since the Merc is a larger and heavier car, it will probably be a slug. It'll get you around town OK, but that's about it.

[lonewolf]

If the Merc is an automatic the crank is machined to work with the air cooled converter. It has kind of a pilot about the size of quarter machined into the end that the converter goes into .If the 8ba was a manual transmission the crank may have to be machined to work with the automatic converter. If the Merc was a manual transmission you will be good

[Solo_909]

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Originally Posted by lonewolf

If the Merc is an automatic the crank is machined to work with the air cooled converter. It has kind of a pilot about the size of quarter machined into the end that the converter goes into .If the 8ba was a manual transmission the crank may have to be machined to work with the automatic converter. If the Merc was a manual transmission you will be good

Good to know, they both are manual so I guess I’m good.

[Solo_909]

Originally Posted by tubman

That list may be OK if you want to make your 8BA LOOK like an 8CM, but again, using the 8CM heads will cut compression from an already low 6.8:1, and combined with the larger (and rarer and harder to work on Merc carb), may cause performance problems. Since the Merc is a larger and heavier car, it will probably be a slug. It'll get you around town OK, but that's about it.

Hmmm, I’ll be able to tell that much just from swapping the heads? I could use the 8BA head. They just need to be painted. I just wanted things to appear stock.

[tubman]

Originally Posted by Solo_909

Hmmm, I’ll be able to tell that much just from swapping the heads? I could use the 8BA head. They just need to be painted. I just wanted things to appear stock.

Or, you could have the 8CM heads milled enough to get you to a .050 "squish" over the piston . You would probably have to do some grinding to bring the head to a uniform combustion chamber. Then you would have the best of both worlds. I believe it is common knowledge that increasing compression is the easiest way to pick up power in an otherwise stock flathead. You might as well take advantage of today's better fuels.