here we go again... does anyone make 3 7/8

[OHV DeLuxe]

Here is one Jim Khougaz did in 1956 at CT-Automotive.
I started a thread here about pistons and was advised to use stock Ford pin height.

[chuck stevens]

Jim I was 6 years old when this crank was turned, proof that almost anything you can think up has already been done, but it's still fun, thanks Chuck S.

Originally Posted by OHV DeLuxe

Here is one Jim Khougaz did in 1956 at CT-Automotive.
I started a thread here about pistons and was advised to use stock Ford pin height.

[Bored&Stroked]

Originally Posted by GreenMonster48

Exactly my thought. Lots of hoop jumping and machine work for what? A couple extra cubes?

Actually no extra cubes - same stroke it started out with, just smaller journals and early rods.

[the cooch]

Gentlemen, thanks for your attentn to the Ford Barn, really helpful and enjoyable for guys that dont get out much.The 3 7/8 cranks seems like a fantastic archeological exercise to me! No offense to anyone's age! From my limited understanding, there was a window between '46-48 where the cranks had stabilized at the common, later, main bearing size (2.4990) with the larger rod journals (2.1390) but still only 3 3/4" stroke. The 1/16 offset grind and the small journal rods would give a theoretical displacement of +/- 247c.i. were pistons made with the pin relocated closer to the pistons" top". Main and rod bearings would be stock parts too. Blocks as far back as '42 seem to accept this rotating assembly. Correct so far? So for a few years did engine builders use pop up heads, custom made pistons, or both and who made what? Probably a small h.p. difference but torque you could feel in the pants? We're cranks stroked by really ingenious racers before the large journal version was available using really thick bearings in the early rods? In one discussion i had, using stock pistons, early rods and the offset crank for the displacement increase was possible but the pin location required pop up heads and the top ring could exit the deck surface in some cases. Apparently not? In another discussion, it was theorized that Ford was about to make the bearing changes but the war postponed it until Mercs could be sold for more money and make up the cost of changeover. I like the idea that the engineers would give a leg up to racers who chose Ford running gear, with more wins adding to the reputation of the brand. I have been intrigued by the idea of building an engine like this as I am cursed with an over active imagination, strong appreciation of nostalgia, and almost no sense of practicality. Any elaboration would be most interesting to myself, and I'm sure others. I don't want to call anyone "old" around here, but perhaps some experienced builders can add some clarity to this concept, having "been there, done that". Thanks! -Chris

[Bruce Lancaster]

Easy interchange would run '39-48, with the later cranks easily transplanted into those with either floater or locked rod setups. Prewar engines need the later seal parts for later cranks.
All the '39-53 cranks will go into the same mains, 221 cranks are the small journal type for 91A and 21A rods, 239 and 255 cranks have the large rod journals.

[Chisel]

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So that crank has been stored in that box since 1956 and being a small journal crank it must be warped and unusable.

[scooder]

Chris,
There's a lot of Ford pistons out there with 5/16" from the crown edge to top of first ring. These won't reach the top with an 1/8" stroke. Also all the OEM Ford pistons have the crown edge quite a bit lower than the deck. These both make the use of them with the 1/8" stroke ideal.
Martin.