Flathead Crankshaft
Fleet Owner
Joined: Jul 2004
Posts: 27,299
Likes: 1,059
From: NM
Do you mean to verify if a seller is telling the truth about a crank for sale? Or on your existing engine? If on your existing engine, the piston crown-to-pin height will tell you.
At any rate, I think I'd put the crank with two throws horizontal. Then get two long straightedges, and put one on each of the two horizontal throws, with the straightedges on the centerline of each throw, parallel to the crank. Then measure between the straightedges and divide by two. It depends how accurately you can eyeball the centerlines. A Merc crank would have 8" between the striaghtedges, a Ford would be 7-1/2".
There are forging marks that allegedly identify Merc cranks, on the front counterweight. I can't remember what it is, 4TL8Ford probably knows, or MTFlat....
At any rate, I think I'd put the crank with two throws horizontal. Then get two long straightedges, and put one on each of the two horizontal throws, with the straightedges on the centerline of each throw, parallel to the crank. Then measure between the straightedges and divide by two. It depends how accurately you can eyeball the centerlines. A Merc crank would have 8" between the striaghtedges, a Ford would be 7-1/2".
There are forging marks that allegedly identify Merc cranks, on the front counterweight. I can't remember what it is, 4TL8Ford probably knows, or MTFlat....
Last edited by ALBUQ F-1; Aug 2, 2007 at 09:37 PM.
Lead Driver
Joined: Oct 1999
Posts: 6,779
Likes: 556
From: Kalispell, MT
Some merc cranks have a square-ish dimple on the front counterweight.
Also check the cleanout plugs. Typically Ford 3 3/4 used 3/8" plugs while the merc 4 used 5/8" plugs.....however Canadian merc cranks have been reported with small cleanout plugs.
The only sure way it as Ross suggested - measure the throw.
Also check the cleanout plugs. Typically Ford 3 3/4 used 3/8" plugs while the merc 4 used 5/8" plugs.....however Canadian merc cranks have been reported with small cleanout plugs.
The only sure way it as Ross suggested - measure the throw.
Thread Starter
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Senior User
Joined: Jul 2006
Posts: 391
Likes: 0
From: Peterborough, Ontario
Thanks, it is a crank I have picked up with an engine a while ago (block and pistons are gone), it was a 53 truck engine. Are all Ford 53's 239 engines or were some 255's. It does not have the dimple on the counter balance and I am almost sure it is a 239 crank untill someone told me that Ford engines in 53 were 255 cu.
wgc
wgc
Post Fiend
Joined: Jun 2001
Posts: 7,493
Likes: 7
From: Erie, pa
After almost 60 years of the 8 series Flathead engines being used repaired, modified etc the only sure way to tell what any individual part is would be to find a part number or measure.
NOTE: Part numbers weren't stamped on anything important.
I just pulled apart a Flatmotor in a 51 Panel, Left Side Head 8BA (Car Type), Right Side Head 8CM (Merc), Block Red Paint (Truck, Flaking badly). Conclusion, after measuring, Typical late Ford Flathead.
NOTE: Part numbers weren't stamped on anything important.
I just pulled apart a Flatmotor in a 51 Panel, Left Side Head 8BA (Car Type), Right Side Head 8CM (Merc), Block Red Paint (Truck, Flaking badly). Conclusion, after measuring, Typical late Ford Flathead.
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Senior User
Joined: Jul 2006
Posts: 391
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From: Peterborough, Ontario
Thanks, I didn't think the 255 was used in the Fords from the factory, but i thought I had beter check with the experts before I gave away a 4" crank.
wgc
wgc
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Post Fiend
Joined: Jun 2001
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From: Erie, pa
Originally Posted by cts1954
Thanks, I didn't think the 255 was used in the Fords from the factory, but i thought I had beter check with the experts before I gave away a 4" crank.
wgc
wgc
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Post Fiend
Joined: Jun 2001
Posts: 7,493
Likes: 7
From: Erie, pa
Originally Posted by cts1954
Sorry for calling you guys experts, what would be worse is to get rid of a 4" crank for $50.00, Canadian dollars as well.
wgc
wgc
(Technical Talk)
Lead Driver
Joined: Oct 1999
Posts: 6,779
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From: Kalispell, MT
Last I checked US and CAN dollars are on par
Don't discourage him Dick, I like it when I'm thot of as an expert!! It doesn't happen very often - just let me bask in the glow
.......you can fool all of the people some of the time and some of the people all of the time, but you can't fool mom.... "Capt Penny"
Don't discourage him Dick, I like it when I'm thot of as an expert!! It doesn't happen very often - just let me bask in the glow
.......you can fool all of the people some of the time and some of the people all of the time, but you can't fool mom.... "Capt Penny"
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