Just picked up a Flathead Mercury 255 to put in my 1952 F1. Is the 255 Merc basically the same thing as the Ford 239 but with a larger crank? Will it just bolt right in my truck? The engine runs but I plan on doing a complete overhaul before putting it in. Really glad I found this forum! Very cool!!!!

Sean Kelly

 

Sure it fits -- new member Sac52 just posted a pic of his in the "Show us your engine" thread, p. 4

Be sure yours looks just like his when you finish!

Welcome to the forum!

 

Congratulations on your excellent choice of power plant. Everybody loves a flathead, at least those who know what "real style" is do!
There is no exterior difference between the 239 and 255, you actually have to measure the stroke to really tell the difference (don't trust what the heads say). The water pumps are the difference between car and truck engines as they are the front engine mounts, just make sure you get the correct ones for your application.

 

Let me say welcome to both of you! my water pumps were Mercury (car?), and my heads said 8BA, and I was hoping the crank was Merc. Engine was painted and rebuilt by PO. Had a 50/50 chance, and it ended up a stock Ford. Good luck with both of your trucks!

 

Welcome to the FTE, the 1950 F1 I picked up in December had a 49 or 50 Mercury Flatead in it. they didn't bother to change the water pumps either, they just used a set of custom made wooden blocks (3X3 or 4X4 ?) and really long bolts to mount the engine.

the mercury intake manifolds have the 4 bolts for a different carb, you can interchange the intakes from ford as well, and as stated above most everything is interchangable with Ford. If you order new piston's they are specific for a merc due to the larger crank throw.
what oil pan does the merc have? A stepped one or one for for car? you may need a truck oil pan (rear sump) most of them have the large cleanout inspection cover.

Cheers

Josh

 

LOL, my PO didn't even bother with wood, just had the oil pan resting on the drag link. (Ford car engine)

 

I think the Mercury cranks also have a larger bolt on the nose of the crank than the smaller stroke Ford. Don't recall the sizes though.

 

Cool, thanks for all the input guys! I think I will be picking your brains for a while as I go through restoring this engine.
Haven't really started tearing the engine down yet. I had surgery on my left hand so it's sorta slow going, doing everything one handed. I did manage to get the intake off and she looks pretty clean inside, like I could just fire her up right now! Inside I found stamped on the block, 1BA. From what I read online, the engine is a 1951 Merc. Different from what the guy who we bought it from said. Can't wait to dig in deeper and measure the stroke. The mercs had a 4" inch, if I remember right where the Fords had a 3.75".

Thanks again guys!

Sean Kelly

 

I have a Mercury engine in my 1952 M-1

I don't know the size. Were the Canadian Mercury Truck engines 255 ci? I assumed it was 239 ci.

Whatever it is it sure runs great!

 

yep the Mercs have the larger displacement (255) per the 4" stroke vs the Ford 3&3/4" stroke.

here is a great site I find myself going back to quite often.
Flathead Specifications: 1949-53 V8

Cheers
Josh

 

I didn't think the Merc trucks had 255's either; the VanPelt table is for car engines. At the time, trucks were focused on operating economy, the Merc engines were all Ford had in the way of an "upgrade" engine for luxury cars.

 

Well, Ok Im definitly no expert on the matter. LOL
I thought all the late style flatheads had the same stock bore of 3.1875" so if it had a larger stroke ie the 4" crank vs the 3.75" you would have a larger displacment, ?

So now I'm wondering? So Jims truck (M1) is in fact a mercury truck with a mercury engine but only has a 3.75" crank??? I'm confused, but maybe learning something new here today as well.

I wasn't under the impression that the Vanpelts site was just dealing with cars? hmmm I do sometimes tend to miss things when reading?

I guess if some mercury engines (trucks) came with a 3.75" crank then thats a very good example of just because it says merc on it does not neccesarily mean its got a 4" stroke! need to measure it to be certain!

Josh

 

I would measure it to be certain in case of a rebuild in its last 50+ years of life. No telling what was put in there.

 

I was looking on the internet and I found this reference for 1948-51 engine sizes in Mercury Trucks: 1948 thru 1951 Canadian VIN Plate

I think that it is likely that my truck has a 239 ci engine.

 

Jim-- Measure to find out. Because SIZE MATTERS!!!