51 Merc Flathead Question

gmanrides

gmanrides

Senior Member
I have a 51 Merc flathead motor that I bought less the bell housing. I purchased a stamped steel bell housing. The bell housing looks correct and all mounting holes look good. The problem is it will not clear the pressure plate. It has a 10 spline clutch input shaft looks to be around 1 3/8-1 7/16 rough measurement, disc around 11-11 1/2". The oil pan has the three bolt bracket that is attached to the starter plate. Where did I go wrong? Thanks for the input.
 
Sounds like it is either a truck engine or someone has put a truck clutch and pressure plate on it. It would require a truck bell-housing to use an 11" clutch or the passenger clutch and pressure plate (the better way to go). It may also require a different flywheel or the re-drilling the current one. My Green Book only goes through 48 passenger and 47 truck, so it's not much help.
 
I guess anything is possible. The engine has the 8CM on the heads, the spacers for the motor mounts still bolted to the water pumps and the air intake from the carb pointing to the rear of the engine.
 
I wouldn't use the 11" clutch for a car, or even a half-ton truck. Way overkill, and I doubt it would clear a Car bellhousing.
 
Are the bolts that fasten the pressure plate to the flywheel equidistantly spaced or are they arranged in a pattern of two-two-two spaced closer together, does the pressure plate have fulcrum weights sticking outside the housing? I believe a Merc would have a Borg and Beck pressure plate with the equidistantly spaced fasteners and a Ford car or truck would have a Long pressure plate with the three close pattern and the fulcrum weights sticking out. A photo would help.
 
Here are the pictures:
 

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I checked VanPelts also just trying to figure out this puzzle. If I have the right bell housing why such a big clutch and what was on there before?
 
gmanrides said:
I checked VanPelts also just trying to figure out this puzzle. If I have the right bell housing why such a big clutch and what was on there before?
Click to expand...

You've got a truck 11" clutch and flywheel on your Merc engine. The stock '49-'51 Merc clutch was 10", so someone over the years switched parts on your engine, very common. You need to either find a Merc flywheel that accepts a Borg & Beck (or diaphragm) pressure plate, or have your truck flywheel re drilled for a smaller pressure plate.
 
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Thanks Bob, I am just trying to get it set up to fire to see what I have to work with. If all else fails I have a buddy willing to swap a 59A with a 3spd top loader for a SBC I have.
 
OK, that is a Long style pressure plate. SOOOO you either have a truck 239 that has had the ancillary heads,pumps, intake from a Merc swapped on, or a Merc that has had truck flywheel and clutch swapped on. You can either find a cast truck half bell and run it or do as V8 Bob suggested and reconfigure the flywheel/clutch. Just make sure you have the correct starter plate for whichever half bell you end up using. I think Bruce Lancaster once said "..all early Ford parts will interchange except the exact pile you have sitting in front of you..."
 
I would suggest you leave the clutch off so you can start the engine. Do a compression test. This may tell you the condition of the engine,but not whatit is. Pulling the heads would be the next step. Re-drilling the flywheel would be the cheapest option, I've done many times. All this depends on the application. The bell housing in the photos are for an earlier style trans. I think the truck housing was cast. I've never used this type assembly.
 
Since all of the 8BA family of engines share the same block & nearly all the internal components with exception to the crankshaft and cam, you could come across any combination of parts. A person has to look at the crankshaft counterweight cheeks and see that the measure 6-inches across. The cam will generally have 8CM in the casting or 1CM/EAC if it is a later engine. The early 51 Mercs still had the early style transmission and the late 51 Mercs have the narrow 4-bolt Borg Warner pattern same as the shoebox Fords with the 1-inch 10-spline input. The late 51 Merc bellhousing is a prize in my way of thinking since you can adapt many more types of transmissions to it and it has a lot of room inside for different clutches. With the earlier stamped half bell you are confined to the early Ford pattern with the 1 3/8-inch 10-spline input (Mercury/Borg Warner overdrives if you like side shift).

A person can either adapt back to the 10-inch Borg & Beck clutch of the mid century Mercs or you can adapt to the 9 or 10-inch Long style clutches that were used in the earlier Fords if you want one that is easier to source. There are also some GM typed diaphragm clutches that can be adapted to work with the early or later type transmissions depending on what a person prefers.
 
rotorwrench said:
....There are also some GM typed diaphragm clutches that can be adapted to work with the early or later type transmissions depending on what a person prefers.
Click to expand...

Please provide more info on diaphragm clutches for the large 1 3/8" input shaft & T/O bearing. Fort Wayne told me that such was not available. Thanks.
 
Ol' Ron said:
I would suggest you leave the clutch off so you can start the engine. Do a compression test. This may tell you the condition of the engine,but not whatit is. Pulling the heads would be the next step. Re-drilling the flywheel would be the cheapest option, I've done many times. All this depends on the application. The bell housing in the photos are for an earlier style trans. I think the truck housing was cast. I've never used this type assembly.
Click to expand...
I'm all confused today! I was mixing up two different post!!! Anyway, I agree with Ol' Ron, I would re-drill the flywheel and use a 10" clutch. You are not going to like the 11" Truck clutch.
 
The commercial version is the one made by Centerforce. It uses the GM style diaphragm pressure plate cover with special finger extensions added to the diaphragm. The GM type is from a later 70s Camaro and maybe other applications but you have to get creative for a plate to work since I believe thay are of the 9.5-inch family and they work on a Borg & Beck evenly spaced 6-bolt cover pattern. I've heard of folks having the 1 3/8" spline hub installed on a later disk assembly, But I think centerforces plate can be had in that spline size.
 
Well things are not as they seem. Even though the engine would turn it will not make a complete revolution. I pulled the heads and intake and from what I can tell I have a Ford block with all the Mercury accessories. I guess I will pull the pan and take a look. The bore seems to be stock but the stroke is not 4.00. I did notice one valve not opening, stuck? maybe? probably?
 
I wonder if there is a good machine shop in mid TN familiar with flatheads. Even though I haven't seen any cracks I think it needs to come down and be cleaned and inspected.
 
It looks like you have the same setup I do. You need the cast iron merc bell housing with the cross shaft to use the clutch setup you have. I have an 11" clutch in my 50 car with a full race flattie (286 CI). I like it. To each his own.
 
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