Technical Ford flathead stroke question

First off new to the site hope I'm posting in the right section if not point me in the right direction! My question is pertaining to my new project I have a 49 ford f1 stock and still running. Of course it's time now for a freshen up of the engine and truck to be honest. What is the actual gain in hp or tq if I were to go with the merc 4" or bigger stroke crank all thing being equal in the engine build? It will be a very mild street build more for dependably. In all actuality the 3 3/4" is perfectly fine this is more of a curiosity question!

 

Question better served over on the Ford Barn. Lot of knowledgeable flathead engine builders. To add my two cents worth, you are dealing with an engine that stock was 85 or 100 horse power. You can get it up to 125/135 with simple mods but after that it gets expensive. That being said, there is no substitute for cubic inches, then you have to get it to breath.

 

Thanks for the info I'll repost in ford barn, and yes their is no replacement for displacement!

 

Well, for comparison purposes.

In 1949 the 8BA was rated at 100 hp and 180 ft-lbs of torque. The '49 Merc 9CM motor was rated at 110 Hp and 200 ft-lbs of torque. Most everything else was fairly similar between the two motors including the 6.8:1 compression ration.

 

That's about the best answer I could have asked for and I can't belive I didn't just compare the two in the first place! Brain fart I guess, thanks frozen merc

 

I am pretty sure that the mercury had lower compression due to the heads. Ford made mercury heads that had a deeper piston pocket in the head due to the stroke. Therefore lowering compression. A performance tip is to put on ford heads since they have a smaller piston pocket therefore smaller cc chamber therefore more compression.


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Ah, but wouldn't the increase in stroke also bring an increase in compression?

 

Ford vs Merc pistons had different pin to top heights so the height above the deck was the same. Ford and Merc made different heads with slightly different combustion chambers, but not with a hollow for a pop up piston.

 

Money! The Ford will be an adequate cheap chug, the Merc will be a bit more powerful. There are original and now aftermarket 4' cranks available, search HAMB and Barn for originals, speed catalogs for others.
Also...you have a motor...LOOK!
Merc cranks appear everywhere as it was easy and cheap to get a Merc crank when you got a rebuild long ago. What it says on the head is meaningless.