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Old 10-10-2015, 08:28 PM   #1
Theholygrehl
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Default 4 inch crankshaft

1940 ford 1 1/2 ton truck stock engine. Did the bigger trucks have a 4" crankshaft. Or are they the same as the smaller 1/2 tons? Are the bigger truck engines any better. Any help would be great thanks.
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Old 10-10-2015, 09:02 PM   #2
4tford
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Default Re: 4 inch crankshaft

4 " stroke came out in 1949
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Old 10-10-2015, 10:49 PM   #3
qmdv
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Default Re: 4 inch crankshaft

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Originally Posted by 4tford View Post
4 " stroke came out in 1949
Was it only Mercury or did the big trucks have it.


Tim
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Old 10-11-2015, 03:37 AM   #4
Theholygrehl
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Default Re: 4 inch crankshaft

So then is there anything different with the big truck engines?
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Old 10-11-2015, 04:26 AM   #5
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Default Re: 4 inch crankshaft

I'm looking at a flathead it has 59 on the bell housing and 59a b on the heads. I'm told that it was a stock engine that came out of a 1940 1 1/2 ton truck. Does that sound like it would be correct? I've seen somewhere where people say that the bigger trucks had thicker walls is that truee?
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Old 10-11-2015, 04:53 AM   #6
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Default Re: 4 inch crankshaft

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As far as I've measured, the truck blocks are the same thickness casting as the same year car block.
The 59 on the bell puts that engine post war. So not the stock '40 engine.
Martin.
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Old 10-11-2015, 05:12 AM   #7
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Default Re: 4 inch crankshaft

So then because of the 59 on the bell housing could this engine have the better crankshaft? The guy is telling me that it has the better crank but I don't know if he's full of crap or not.
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Old 10-11-2015, 05:32 AM   #8
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Default Re: 4 inch crankshaft

I think he's full of crap. The 59A crank is essentialy the same as the original 40 crank, except for the seal arrangement on the back, 59A has a seal, the stock 40 crank has a slinger arrangement.
The 4" crank is for 49 up Merc 8CM.
Now you can fit a 4" crank in a 59A as you can in the 40 stock block. This is claimed a lot, to often it's horse piss. If he won't let you pull a head and measure the stroke, it's a stock 3 3/4" Ford crank. And should be valued as that. A 4" crank is only a 4" crank when it measures 4". There are clean out hole size difference but this isn't writ in stone. So it has to measure 4". If it does have the 4" crank it needs to be proven, due to the vast difference in values.
Martin.
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Old 10-11-2015, 05:35 AM   #9
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Default Re: 4 inch crankshaft

Quote:
Originally Posted by Theholygrehl View Post
I'm looking at a flathead it has 59 on the bell housing and 59a b on the heads. I'm told that it was a stock engine that came out of a 1940 1 1/2 ton truck. Does that sound like it would be correct? I've seen somewhere where people say that the bigger trucks had thicker walls is that truee?
First of all, that engine did not come in that truck from the factory. The "59" denotes as a post-war engine (the "5" indicates 1945 design, I believe). All "59" series engines are essentially the same; the plain "59" on the bell housing is the basic run of the mill engine. Now if it were something else (like "59L" or "59Z"), he might have some basis for claiming it is something special, but in this case, he's just blowing smoke. I wouldn't believe anything he says. Let your eyes be the judge on this one.
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Old 10-11-2015, 05:43 AM   #10
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Default Re: 4 inch crankshaft

Thanks guys. Here are some pictures that he sent me
Attached Images
File Type: jpg Flathead.jpg (37.4 KB, 135 views)
File Type: jpg imagejpeg950.jpg (63.5 KB, 122 views)
File Type: jpg IMAG0685.jpg (48.9 KB, 110 views)
File Type: jpg IMAG0684.jpg (55.4 KB, 110 views)
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Old 10-11-2015, 05:44 AM   #11
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Default Re: 4 inch crankshaft

If the crankshaft is a stock 59A crank it will NOT be 4". All the 59 engines had 3-3/4" stroke. However, some 59 blocks are 3-1/16" bore but most are 3-3/16". It is reasonably easy to remove a head and measure both the bore and stroke which is what I suggest. If one of the selling points is related to the crankshaft the seller should not object to the verification review.
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Old 10-11-2015, 09:21 AM   #12
rotorwrench
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Default Re: 4 inch crankshaft

In 1940, some trucks were equipped with the 90 horse power 239 cubic inch engines. These engines were manufactured for Mercury cars and trucks beginning in 1939 till the war started. There was no difference in the crankshafts between the 221 cid blocks and the 239 cid blocks in this time frame. The pre-war 239 blocks are what is sought after since it has thicker cylinder walls than any of the earlier 221 cid blocks or later 59 series blocks.

As was already mentioned, the 59 series cylinder block was follow on design for civilian production beginning just before the war was over. They were mostly 239 cid but they have a less thick cylinder wall than the pre-war design 239 block.The exception to the rule is the 221 41A block that was produced as a 221 cid replacement just toward the end of the war in late 1944. This block also has the "59" on the back so a guy can end up with a thin wall cylinder even if it has the 59 series casting marks.

The 8CM 4-inch crankshaft that was made for Mercury cars using the 8BA type cylinder block was never set up for floating con rod bearings like the earlier 59 series & prior. They are 255 cid engines and they use insert type locked in place con rod bearings.

Last edited by rotorwrench; 10-11-2015 at 09:28 AM.
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Old 10-11-2015, 10:02 AM   #13
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Default Re: 4 inch crankshaft

Wrench,
The 221 And 239 cranks were different, the rod bearings journals are different sizes.
Martin.
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Old 10-11-2015, 11:33 AM   #14
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Default Re: 4 inch crankshaft

It's your money. If the engine price is considerable it would be wise to remove both heads. As mentioned check the stroke, but more important look very closely at the valve to cylinder area for cracks. Unless someone has installed a merc crank and pistons it will be a 3 3/4" crank. Nothing wrong with the 3 3/4 crank set up, just fewer cubic inches.
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