Old FH race cranks ( before the 8BA )

[3W Hank]

This might sounds Very odd, but for a start ; I has bought a 1941 ported race block and its .+0.125” or 3.3125” bore now and I had this upp here before and no one belived it was sonic tested to a hair averege over 0.25” wall ( by seller in USA ) Se picture before topics.
Block is still at US shipper but will leave LA soon.
Anyway, I has a idea on my 5W coupe to be a pre 1950 LA street racer.
I’m not found on the 8AB stuff at all,
I’m not pre-war but after war and before 1949.
We has all our strange illness..
I has leaved my Scintilla to a Kurten distributor and most parts both Henry or Lincoln and speedparts is actually before 1949.
I do has a new grinded Merc 4” crank with bearings and rods, but I got a bad eye on it.
I’m limited to a cubic under 300 and I know stroke is not gain as much as cyl bore, plus stroker cranks pressure cyl wall harder.
As a engine guy I’m aware of nothing beats cubics inches.
But I talked to a guy here and he said ’back in the days’ those blocks and std later 59 was bored more than 1/8” over std.
My block had not see water for 50 years or more.
On wall thickness I can’t say but its a sonic test.
I can re-test but one never know of a pin hair.
So lets say I don’t go 3.375” but stick at 3.32”.

On cam I has a Potvin 425 and dual LZ carbs, aluminium flywheel and 4.44 rear.
No burnouts ( drags ) but I like rew on gears.
I’m not focus on get as much cubic as possible here but more ’what’ did the guys do in 47/48 ?

I had a 1938 crank ( 3.75 ) I guess its a 2” rod and but the smaller main diameter.
But the std 1941 crank might has the same main as the later 59AB.

So my question is, how did the guys do before the 4” Merc crank came out ?
What was the trick crank shops sold them ? ( based out from what crank/year )
-I love the history.

( Some say, forgett about this nonses and get a new ( Taiwan ) 4.25 crank.
No, I like to do it the complicated ( and odd ) and maybe the expenive way.

If anyone has old race crank that fit this, call me.

Ideas ?

[Ronnieroadster]

I have had previously and still have one early block that's bored 3-7/16 so a larger bore than 3-3/8 was and still is possible if one chose to do it.
Another item that added cubic inches prior to the 4 inch Mercury crankshaft the Ford 3 3/4 stroke crank with the larger rod journals but still floater rod style journals was offset ground to the two inch rod journal diameter. For rods the Ford 21A rods would be used you now had a 3-7/8 stroker. So a stroker crankshaft did exist prior to the Merc cranks coming out in 1949.
Ronnieroadster

[KiWinUS]

I have 2 59AB Cranks from old race engines one engine I still have. Both cranks are 4.250” stroke. Neither show signs of welding. Both have 2” crank pins. No idea who made/modified them. (Not for sale) I know back in 60’s? Speed-O-Motive sold stroker kits for flatheads and I believe other engines also. Not much help but they were out there.
I believe C&T also sold strokers back in the day.

[flatjack9]

I have a C & T welded 4 1/2" stroker crank.

[3W Hank]

That deal to get a big journal 3.75 crank to 2” is possible and one can find bearings at - 0.04” to get the 3.875 stroke.
But next question, what C-H had piston companys before 49 ?
Was that stroke common ? ( regards race pistons )

I guess crank shops welded rod journals upp but did they really was at 4.5” before 49 ?

I’m Ok at 4” ( find a old crank/welded to 4” ) or the fuzz get a 3.75 to 3.875” as I can do it.
If my block can handle more bore I’ll just think that was the idea back then, next was stroke.

So 2 questions.
Did they weld to 4” pre 49 ( not at the 50’s or 60’s ) and was piston C-H aviable 1948 at 4” and 3.875” stroke ?

Bigger bore and that sneaky stroke - I like it.
Shore its way odd 2024 ( but thats anoter story.

[38 coupe]

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In the four part series of articles written by Mark Dees in the 1970s he describes the "big engine" in 1948 being the "1/8 by 1/8" (268 cubic inches), the bore being 1/8" over standard 239 engine and the stroke 1/8" longer than standard 3.75". The longer stroke was done by offset grinding the larger journal 95 / 100 horsepower rod journals, finishing them at pre-war Ford diameter, and using pre-war Ford connecting rods. In the articles Mark Dees describes this combination being done in 1939 when the first Mercury engines were available.
Starting in 1949 the "big engine" moved up to the "3/8 by 3/8" (296 cubic inches), the bore being 3 3/8" and the stroke being 4 1/8 (3/8" longer than Ford).

I have an old hot rod crankshaft stroked from 3.75 to 3.875. I don't know what I will do with it since I am not going to pay Egge or another piston manufacturer to make custom pistons for it. Your hot rod engine might have one too, if it does try to save the pistons since replacements are custom job these days.

[jimTN]

If you want torque, bigger is better, RPM will be best and safer with the shorter stroke. IMHO

[3W Hank]

1/8 by 1/8 sounds nice.
Thanks for info.

[Tim Ayers]

Originally Posted by flatjack9

I have a C & T welded 4 1/2" stroker crank.

Dang!

[Ronnieroadster]

Have a set of 3-7/16 Jahns pistons for a 4 inch stroke. And a Merc crank stroked to 4.250 if anyone needs them could be delivered to Hershey. Send me PM for more info.
Ronnieroadster

[Bored&Stroked]

Another option is to run STD 3 3/4 stroke pistons and machine the chambers about .0625 deeper and run a 1/16" pop-up piston. The only issue is that if the block is already relieved, then you don't want to do this as the ring package is too close to the relief.

Also, it isn't that expensive to change the compression height of Ross pistons - I do it all the time. Call them up directly and talk to "Ed" in sales - he will work with you.

For a naturally aspirated engine I leave the ring package in the standard Ross location. If I'm running a blown engine with a heavy relief, I like to move the ring package down a bit (to keep heat out of the top ring).

Lastly, talk to Ed about metric ring packages --> 1.5, 1.5, 3.0mm or similar. The modern ring packages are a LOT better than the older Grant/Hastings stuff we all ran for years.

[Tim Ayers]

Originally Posted by Bored&Stroked

Another option is to run STD 3 3/4 stroke pistons and machine the chambers about .0625 deeper and run a 1/16" pop-up piston. The only issue is that if the block is already relieved, then you don't want to do this as the ring package is too close to the relief.

Also, it isn't that expensive to change the compression height of Ross pistons - I do it all the time. Call them up directly and talk to "Ed" in sales - he will work with you.

For a naturally aspirated engine I leave the ring package in the standard Ross location. If I'm running a blown engine with a heavy relief, I like to move the ring package down a bit (to keep heat out of the top ring).

Lastly, talk to Ed about metric ring packages --> 1.5, 1.5, 3.0mm or similar. The modern ring packages are a LOT better than the older Grant/Hastings stuff we all ran for years.

I second the suggestion of going to metric ring packs as well.

[3W Hank]

Right now my 41 block is bored 3.5/16" or 1/8" over std ( relived ) but as cylinders is told be tapered I need hone and custom pistons. Another way is go next step up and bore 3.3/8" or 3/16" over std.
But to go 3.7/16" or 1/4" over std bore is tuff.
I dont mind get custom pistons, but a cool deal is old Jahns race pistons ( but hard to find - my guess )
The 1.5 mm rings is not for me critical, I can if I like get some tension out of older rings tech.

But a pre 49 idea and bore + 1/4" and stroke a 3.75" crank + 1/8" to 3.875" and that get me 288 cubic.

One idea is use a stock 3.75" 59AB crank, that get 278 cubic, and less work and less cylinder pressuare.

Light of the crank some weight and light flywheel/pressuare plate.
Ideas on that ?

I has a short nose big main and 2" rodjournal and the 21A rods.
I has also a std 59AB crank.
Somehere had a crank 'maybe' for sale to, stroked 1/8".

[Tim Ayers]

Originally Posted by 3W Hank

Right now my 41 block is bored 3.5/16" or 1/8" over std ( relived ) but as cylinders is told be tapered I need hone and custom pistons. Another way is go next step up and bore 3.3/8" or 3/16" over std.
But to go 3.7/16" or 1/4" over std bore is tuff.
I dont mind get custom pistons, but a cool deal is old Jahns race pistons ( but hard to find - my guess )
The 1.5 mm rings is not for me critical, I can if I like get some tension out of older rings tech.

But a pre 49 idea and bore + 1/4" and stroke a 3.75" crank + 1/8" to 3.875" and that get me 288 cubic.

One idea is use a stock 3.75" 59AB crank, that get 278 cubic, and less work and less cylinder pressuare.

Light of the crank some weight and light flywheel/pressuare plate.
Ideas on that ?

I has a short nose big main and 2" rodjournal and the 21A rods.
I has also a std 59AB crank.
Somehere had a crank 'maybe' for sale to, stroked 1/8".

Put a Jahns decal in the window and nobody will be able to tell what piston you are running.

If you are going big bore, I really suggest looking into metric ring packs for less wear and friction.

For something as crucial as a piston, I would look to get the best I could afford.

[3W Hank]

Tim, all this for me is just a head thing.
I’m only do this get me a smile.
It fill not much more purpose.
So a sticker would be to has to much cam lift in my Hemi NHRA stocker to compare.
I normally work with CP or JE but its also what forging core they has.
Maybe Ross has a better core to this engines.
The 1.5 mm rings is a good size but to thin its make cylinders more critical.
In my 426 I has 0.7 mm diamond coated and gasports in ring and very low tension still they works great but I has 3/4” wall thickness high nickel block.

But I can go out of the box on tires, pistons and valves as bigger new stuff I accept.

Small question might not make any sense, but should I index grind the 3.75 + 1/8” or stay at 3.75.

Another question, the short nose crank, tell me on those vs the longer nose.

[3W Hank]

Found this I took a picture on before.
From a book with Hot Rod Mag old article in.

[38 coupe]

In most of the world short nose cranks are all small rod journal cranks that cannot be stroked. However, Europe did some different things from the USA and Canada and there may be a few short nose large journal crankshafts floating around. Please measure your short nose crank and let us know what the main and rod journal sizes are.

[3W Hank]

The one here is big mains and small rod.
It might been a cross that last year on short nos with big rod (?)
I has a 59 crank to.
Baby stroke sounds cool ( for me )

[38 coupe]

In the USA from 1939 through 1942 the 85 horsepower engines used the larger main journals and smaller rod journals with the longer crankshaft.

[3W Hank]

Well I ’heard’ it was 2 versions 1939, long nose and big main and small rods but also big mains and big rods.
I also hear the 39 had thinner counter weights, but I’m not shore on either here.