~FLATHEADS~
1. OVERVIEW & HISTORY                7. IGNITION
2. FUEL FLOW                                8. INDUCTION
3. HEADS                                       9. EXHAUST
4. CAMSHAFTS                             10. LUBRICATION     
5.
CRANKSHAFT
6. RODS & PISTONS
CRANKSHAFT
And now, entering the ring @ 68 pounds
soaking wet, the undisputed heaviest V8
crankshaft in the woooorrrrlld…The Flathead
Ford or Mercury crankshaft is definitely a
heavyweight and in stock form helps
transform the engines energy into usable
horsepower and torque. In this (stock) form
the crankshaft is more than adequate for the
job intended but racers had different ideas
and were able to transform the cranks into
entirely different animals. As most Flathead
fans know, the 24 stud engines cranks
interchange and will be the focus of this
discussion as these later cranks were favored
over earlier 21 stud cranks. With the 59A
engine designation, all crankshafts (Ford and
Mercury) were 3 & ¾” stroke, the only
differences being that the Mercs were nodular
iron versus the Fords which were cast iron.
These are rugged crankshafts with generous
counterweights, 2.139 in. diameter rod throws
and single oil holes in each throw which can
only be used in conjunction with ‘floater’ rods
and bearings. The floater bearing was used on
the Flatheads through 1948 and consisted of
two halves which were fit on the crankshaft
throw, two rods were then fitted one each
bearing meaning you only have (4) rod
bearings for your (8) rods. This was actually a
very good setup, especially for racing (and
preferred by most Flathead racers) as it
provided for two areas of lubrication, one
between the crank and bearing and then the
second between the bearing and rod. The
term ‘floater’ refers to the bearing ‘floating’
between the rod and crank – which is what
you want, especially in a racing Flathead. The
later 8BA (Ford), 8CM (Mercury), engine
designation employed crankshafts with two oil
holes in each rod throw as each rod now was
fitted with insert type bearings such as used
in all modern engines. Why the change? Cost,
it was easier to fit and produce the inserts.
The later (1949-1953) cranks also offered one
other huge difference over their predecessors,
while the Ford cranks retained the 3 & ¾”
stroke, the Mercury’s crankshaft was now 4”.
These cranks became the most desired not
only due to the additional stroke but also
because they were nodular iron and offered
greater strength.
OK, so what did the racers do? Well, in the
early days of stock car racing most followed
the lead of the Hot Rodders, Drag racers &
Lakes racers of California. There were also
some holdovers from the Model T and Model A
engine builders as a few of the ideas used on
those crankshafts still were viable with the V8.
The earlier 24 stud cranks were well suited for
racing and often used in stock configuration.
Many crank grinders would add a groove to
the cranks at the main and rod throw oil hole
for additional lubrication but this method was,
for the most part, discontinued later as the
bearings themselves are grooved. The early
crankshafts were often ‘stroked’ increasing
engine displacement by offset grinding the
rod throws to a smaller 1.999 inch diameter
and then fitting earlier 21A or 91A rods which
were found on the (1939 – 1942) 85-90
horsepower engines. The rods throws were
often welded or ‘metal sprayed’ to allow for
grinders to achieve up to 3/8” additional
stroke (4 1/8” total). When coupled with a set
of 3 3/8” pistons and a block bored to
accommodate them, you had what was known
as a ‘3/8 X 3/8’ engine of 296 cubic inches
which was famous in its day as a top runner.
The early cranks were fine in their day for
racing purposes but their younger brother,
the 8BA was a better choice once available.
So why was the 8BA better? Simple, it two oil
holes for each crank throw providing better
lubrication, especially when used in
conjunction with floater bearings. It also was
available with a 4” stroke factory stock which
meant that you could get your 4 1/8” stroker
without having to do any welding or metal
spraying, which made for a stronger product.
And, if you wanted to go further, it was still
possible with the aforementioned welding or
spraying, and strokes of 4 ¼”, 4 3/8” and 4 ½”
were possible and available. The cranks also
afforded the user of an option of bearings, the
rod inserts worked fine and I’ve used them
with Clevite (Michigan 77) with good results.
But every racer I’ve talked with preferred the
floaters and I’ve also used them with excellent
results and better wear characteristics than
the inserts.
OK, so what did the racers do with them to
make them race ready? It depended upon the
rules they had to work with. Some tracks,
such as Watertown and in the early days,
Waterloo, had cubic inch limits of 250 and
260 respectively. Since the Mercury engine
was 255 in stock form, these limits pretty
much precluded the use of the 4” crank.
Those racers looking for a strong crank would
turn to the 8RT engine used in trucks as I’ve
found many of these 3 & ¾” cranks to be
nodular iron (or what many call a ‘steel’
crankshaft). They’re a tougher crank. Or they
may have purchased a ‘cut down’ crank as
available from C/T Automotive and Ansen.
These cranks, depending on cost and how
radical ones pocketbook could stand, could
have the weight decreased by as much as 10
lbs. which my friend Bob Hayslett related
would make the engine ‘sound like a cat that’
s gotten it’s tail stepped on’ when you
punched the throttle. The example I’ve seen,
(and copied) had both center counterbalances
removed entirely and the end balancers were
polished and wedged for slipping through the
oil shower they work in. Bob once related to
me that he tried to do one himself, installed it
and fired the engine up in his driveway. “It
nearly shook the fenders right off just idling.”
It’s true that you have to add some ‘mallory’
(heavy metal) to the crank after this operation
in order to balance it but still; the response is
pretty impressive with that extra weight
shaved off.
Next, obviously is the stroker. As described
above, many different configurations were
available with each successive jump in stroke
providing added power and torque. Alas, as
the stroke increased so did the angle of the
rod in relation to the piston to the point
where on the larger strokes, the piston barely
has any skirt left due to clearance issues.
This, in conjunction with the long stroke,
somewhat weakened crankshaft and three
main bearings holding the whole assemble
together made for a rather potent yet short
lived bomb. Obviously, the less skirt the
piston has, the less stable it is in the bore and
with the longer stroke, you cannot turn the
RPM’s that a smaller configuration could.
More torque undoubtedly. From my
experience, a good Mercury crank at stock
stroke (4”) works very well and a 4 & 1/8”
stroker works even better.
Cutdowns, Strokers, what’s left? Lastly is the
crossfire (or 180 degree) crankshaft whose
origins date back to the Model T days of
longtime racer and cam grinder Ed Winfield.
Winfield’s T had a firing order of 1-2-4-3
meaning that cylinders 2 and 3 were drawing
off of the same carburetor after the preceding
cylinder in line had already gotten a full shot.
He felt, (correctly) that these cylinders were
not getting as much fuel as cylinders 1 and 4,
which was robbing power from the engine. To
correct this he reconfigured the crankshaft
and camshaft to change the firing order to 1-3-
2-4 therefore ensuring that each cylinder was
getting a full shot. And from what I’ve read
about it, Ed related that ‘although it vibrated a
little’, it went like stink. Or something to that
effect. The Flathead  suffers from the same
problem with a firing order of 1-5-4-8-6-3-7-2;
not only does cylinder 1 follow cylinder 2 but
also, with the center cylinders sharing an
exhaust port, there is the problem of dilution
of the intake stroke from the adjoining
cylinders exhaust. The solution was to use a
‘flat’ or 180 degree crankshaft that changed
the firing order to 1-8-3-6-4-5-2-7 thereby
ensuring a healthy intake charge to each
cylinder. OK so that problem’s solved, now
what. Well, the cranks have a tendency to
vibrate, partially because earlier versions
came sans counterbalances, (or they were the
result of working with a Farmall H tractor
crank, which with some judicious welding and
machining can be fitted), and also due to the
fact that the two sets of pistons headed in
opposite directions accelerate at different
speeds. I’ve only seen one of these early
cranks with the counterbalances and it had to
be a Norden. Even with counterbalances
though, the crankshaft, by its layout, had a
secondary vibration in the horizontal plane
which with the longer strokes can make it
unstable, add the fact that there’s only three
mains and that most of them were raced and
you can deduct why there aren’t too many left
to look at. Still, a very neat idea, but yet
another problem was the cost of such pieces
which I am told was $500 back in the early
1960’s, and then you had to have the
camshaft as well. Flathead Jack offers up
these cranks as done by ‘Hank the Crank’ in
California and I believe they are jewels,
unfortunately for me I don’t have enough
jewels to afford one yet but I’m sure they are
the best of this type of crank ever available.
Lastly, just a little bit on radiuses and
clearances. Ensure your crank grinder
incorporates a generous radius in the
shoulder of each rod or main throw when
grinding as this is much stronger than any
sharp corner. Clearance’s, make them loose
on a racing flathead, 0.002 – 0.0025 rods and
mains and 0.015 end play with rod bearings.
Also, have the throws polished, the oil holes
chamfered and ensure that there are no
raised edges around them. Have your grinder
remove the oil trap plugs and cleanout all that
crud in the oil traps, then replace the plugs
and balance with the assembly. Lastly, ensure
that the crank is absolutely spotless and clean
before assembly. Use a crank brush to clean
out all oil holes and passages, a couple of cans
of carb cleaner do wonders. Don’t trust that it’
s cleaned out coming from the grinder, do it
yourself to ensure that it’s done right.
New Norden 180 degree crank
available from Flathead Jack.
Doug Garrison drove Martin Riiska's
Yellow X @ Lebanon Valley with a
stroked crossfire crank and
supercharger.
Original Norden 180 degree crank.
Original Norden 180 degree crank
(note counterbalances).
Reducing rod journal size allows
for offset and increased stroke.
Original C/T cutdown crank
with grooved mains.
My own cutdown crank - this is a lot
of werk.
Ansen cutdown crank picture,
center counterbalances gone,
fronts and rears scalloped.
Bob Hayslett and Dick May
used C/T cutdowns with
great success @ Watertown.
Clark & Tebow Automotive made
both strokers and cutdowns.
Floater Rods, 21a & 29a,
note big end size difference.
Silver Cad Floater Bearings,
two rods fit on these halves.
8CM Mercury crankshaft, the
most desirable for racers.
Additions 4/1/07
This article is from the March 2, 1956 issue of Drag News by Dean Brown with photos
by Bob Knight. It is the most comprehensive article I have found (to date) on the
Norden 180 degree crankshaft.
Magnesium Rods and Crossfire Cranks available in 1956...
Camshaft looks like a spiral staircase...Nitro for $4 a gallon...
Additions 11/11/07
This article was contributed by Darin Soule and shows how Ansen cut down their
cranks and flywheels for faster acceleration. I've also included my notes as to what I
did with my cutdown.
Lighfening might be a typo..but balancing will add life to an engine.
Get yer body grinder out..
It's a good idea to tape old bearings to the throws to protect them.
Lightened crank and steel caps, a hot set up.
My cutdown crank notes, next time I'll do better.