1. OVERVIEW & HISTORY                7. IGNITION
2. FUEL FLOW                                8. INDUCTION
3. HEADS                                       9. EXHAUST
4. CAMSHAFTS                             10. LUBRICATION   
Hexagon Tool 2 duece, carb. mounts are backwards.
Vic Edelbrock's Super 2 Duece, very good intake.
Offy 2 duece, log type.
Fenton 2 duece.
Offy 3 duece.
Edelbrock 4 - Barrel intake.
Ever see a Canadian Merc - 4 bolt pattern, nice. 180 degree, dual plane design from Ford.
OK, so how we getting the air/fuel mixture
in there? As described before in 'Fuel Flow'
- the air/fuel mixture in a flathead has a
tortuous path, down through the intake
runners to the port, a 90 degree turn
upward past the valves and then another
180 degree turn downward into the
cylinder. Not the best situation for a fullout
race machine, of course that isn't what
Henry was thinking when he built the V8.
Another problem with the engine was of
course the 90 degree intervals in which it
fired and the firing order -1-5-4-8-6-3-7-2
in which cylinder 1 follows cylinder 2. Ford
engineers solved the problem for cylinders
one and two by creating a dual plane 180
degree intake (one runner above the other,
each half of the dual barrel carburetor
feeding half the cylinders at 180 degree
intervals). Still, this didn't address the
cross dilution between the center 4
cylinders, a situation created by the
siamese exhaust ports. In stock
configuration, this arrangement was most
likely deemed acceptable, the stock
camshaft didn't have a lot of overlap, nor
was the engine designed for high speed
operation (most horsepower and torque
ratings were recorded at 3600 Rpm). But,
once racers got their hands on the
engines, things changed and getting more
air/fuel mixture in was paramount to
extracting more horsepower and of course,
more speed.
The first attempt that I know of to extract
more speed from the engine was most
likely a two carb, 'slingshot' type of adapter
but the first attempt to cast a two
carburetor manifold was probably done by
the Hexagon Tool Co. in support of Harry
Millers 1935 Indianapolis attempt. Ford
had contracted Miller to build several cars
for the 500 that year, but there were
problems in procuring the cars, parts, and
materials. Short of time, Miller did the best
he could but in the end was doomed by
placement of the steering box in close
proximity to the exhaust manifold, causing
all the cars to retire or fail in the race. It
was an embarrassment for Ford who took
all the cars and locked them up in a
warehouse for years, vowing not to return
to Indy. Regardless, there must have been
people watching as two pot manifolds soon
took off, especially in Southern California
at the lakes. Along with camshaft grinding,
manifold production was most likely the
first manufacturing done to support hot
rodders and racers alike. The Hexagon unit
is actually quite nice but unless you're
going to turn your V8 around and run
front wheel drive like Harry did, it's a
wallhanger as the carburetors are mounted
to support this arrangement only and
probably won't work to well mounted
Once rodders and racers figured out more
carburetion was better, carburetors
(usually stromberg 97's or 48's) were
added to manifolds as rapidly as they could
be and manufacturers starting offering
several models to meet the demand. Many
of these manifolds were well thought out
and fairly efficient, other's were not. There
has been a lot of commentary on manifold
design - Ron Ceridono goes over it quite
nicely in 'Tex Smith's The Complete Ford
Flathead V8 Engine Manual' in which
velocity, runner length, and port size are
all discussed. In short, larger runners
create less velocity, longer runners may
create more velocity but like the larger
runners - may also lead to a phenomenon
called 'puddling'. Puddling is no good at
low speeds, what the racer or enthusiast
wants is to keep the fuel in suspension in
the air, this takes a certain amount of
velocity to maintain. A common mistake
that many (including myself) make is that
we over carburate our engines, it isn't just
a matter of adding more, or bigger
carburetors in order to get more speed.
Rather it is a combination of correctly
selecting components that work together
in harmony - the sum is greater than the
whole. You can't just stick a manifold on
with two deuces, or a 4 Barrel and go faster
at all speeds, compression, timing, etc. also
have to be considered.
Ok, but we're just talking induction here
so first let's see what a Flathead needs by
using some long eared formulas. I'm going
to apply these formulas to one of the race
engines I've used in the past. This was a
248 cube engine with pop up pistons and a
full race Crane 425-2 radius cam, I turned
it 6000 Rpm at times on a big 1/2 mile
track. Absolute CFM = RPM x CID/3,456
so: 6000 x 248/3,456 = 430 CFM.
Stromberg 97's rate in at 150 CFM each,
48's rate at 175 CFM so I could have gotten
by with (3) 97's. I instead ran a Holley 450
CFM carb. and it ran beautifully. Ok, what
would a strokers' requirements be? I don't
want to turn this as hard so a 296 @ 5300
RPM requires: 5300 x 296/3,456 = 454
CFM. We can reason from this that 3
Stromberg 97's are plenty for full race trim
and probably too much for the street. From
our own experience, this has held true.
Now, we've never had a dynomometer, nor
heavily studied the patterns of fuel flow
through a manifold, our dyno was simply
running them up a dirt road with a steep
grade, if they pulled well up the hill, they
pulled well at the track. I started with the
small Holley, when it started leaking I went
to a 600 CFM double pumper and the
performance suffered until I started
playing with jets and accelerator pumps.
Took a while but we got it to run pretty
good although not as well as the 450 in my
opinion. My father stuck with the
Strombergs for a while and once we got the
bugs out of them (usually leaking, jetting
and getting the floats just right) they
worked admirably. The manifolds we used
were the popular Offy 4 Barrel and
Edelbrock 3 deuce, both 'log' type
manifolds that work well in my opinion.
There has been a lot of commentary about
manifolds as well, in what worked and
what didn't on the street. Barney Navarro
felt, (most likely correctly) that by following
Ford engineers initial design of the 180
degree dual plane manifold, that his
manifolds helped keep the fuel in
suspension and hence worked better at
lower engine speeds. The log type
manifolds tended to allow puddling at low
speeds and then when engine vacuum
drew this heavy charge, performance
suffered as a heavy load such as this
actually takes longer to burn. Once the
velocity is up in the manifold runners, the
fuel is in suspension again and the engine
clears out. I do think that this is a
phenomenon more of concern for the
street as in racing, aside from starts (which
are rolling in stock car racing, and can be
compensated for with that nice Lincoln
Zephyr gear), the race engine is
percolating most of the time and a log type
manifold works just fine from our
experience. Edelbrocks super Dual, Offy's
dual and both makes of 3 deuce manifolds
all worked well on race cars here in the
northeast and aside from the 4 Barrel
models from both manufacturers, I haven't
seen much else on flathead race cars. The
tall Edelbrock and Tattersfield dual I
believe would work very well on the street
as the runners are long and should provide
not only great velocity but also torque at
low speeds, but at this point for me, it's
just theory. My friend Cliff Kotary ran an
Offy 3 deuce with the center throats
blocked off and two Rochester 2 barrels off
of late 50's 389 Pontiacs, with a
riser/adapter to fit them to the manifold.
He ran a 280 cube engine and would push
it to 6000 RPM as needed, ran no fan, on
gas and won the State Fair race 6 years in
a row from 1960 to 1965. This was a log
type manifold, obviously, it worked well. I’
ve seen other designs that placed the carbs
over the ports in close proximity with a
small ‘log’ – my thought is that these
probably didn’t work as well as the
aforementioned Edelbrock, Offy, Sharp,
Evans designs. There just isn’t as much
volume to draw from and in some, there
are a lot edges and obtrusions that would
hamper flow. They may work well at low
speeds but I doubt they’d work as well at
high speeds. OK, a lot of conjecture there,
proofs in the pudding. One thing that is a
certainty is this, ensure that the ports of
the manifold match the ports of the block.
A ridge here will certainly be detrimental,
same goes on the carb. side of the intake. I
have seen many manifolds hogged out, I
don’t think that’s the way to go. The
fellows that cast them up (for the most part
anyway) knew what they were doing and
opening up the manifold ports will
probably do more harm than good, just
match the ends and blend them in nicely
and leave it at that. Also, for racing
purposes we’ve always blocked off the heat
risers in the block with pennies. It has to
be a wheat penny to be right…
Now, how we gonna take care of that cross
pollution in the center cylinders? You can
place a divider in the exhaust port - this
takes up space and restricts exhaust flow
though, it works but you're robbing peter
to pay paul again. Another solution is the
crossfire crank to change the firing order
and get a solid charge into each cylinder
(see ‘Crankshafts’). Stuart Hilborn had an
interesting solution prior to entering the
service in which he placed 4 carburetors
on a manifold, with a larger one over the
ports leading to cylinders 1 & 2, at least
that addressed part of the problem. It
wasn't until after the war that Hilborn first
introduced his mechanical fuel injection
which although it didn't address the
dilution problem, it sure delivered the
goods, under pressure. I ran one of these
early units for years on my racecar and all
I can say is that it woke the engine up
immediately. Acted like an overhead. Once
I got the jetting correct (with methanol), it
never gave a lick of trouble and was so
responsive that during slow laps on a
rough track, I had to be careful not to let
my foot bob on the throttle or I'd be
cracking my competitors nerfs. Another of
my flathead Guru's - Bob Hayslett - once
told me that with methonol "If you can get
a guy on the hood with a 55 gallon drum,
pouring it in there, that's what you want." I
took Hilborns recommendations, then
started adding jet until it was
unresponsive, backed it off and let it be. I
ended up with a 0.060 jet and 14A nozzles,
it worked great although it wasn't the
greatest economy wise. Who cares?! It goes
like stink. Hilborn still produces the
injection units to this day although it’s the
later design, larger venturi’s and butterfly’s
but they aren’t angled to match the ports
like the earlier models. If you get an early
model you’ll need to come up with an
arrangement to get some air cleaners on
there, Bill Marsh made mine and did a
bang up job. Another thing that’s nice
about the injectors is that they have a
mechanical pump – which can be driven off
the crank or the camshaft. You want to
drive the pump at ½ crank speed – this
does away with the electric fuel pump
which (unless you have an old mechanical
bus pump) is a requirement for feeding
more than one carburetor. In racing
electric pumps are frowned upon due to
the possibility of accidents – and the pump
still running, which is a bad situation in a
fire. Of course this can be taken care of by
hot wiring the pump to a pressure switch
which will shut it off when the engine quits
– still, I like the mechanical pump. It’s
interesting to note though that even
though Fuel Injection promised greater
response and power, it somewhat depends
on who was doing the advertising. In the
50’s Art Chrisman of drag racing fame took
an engine to Tony Capana (Wilcap) and
used one of Al Sharp’s 4 deuce intakes
with Stromberg’s. On the Wilcap dyno,
they got more horsepower with the carbs.
than with the injectors. All I can say
though from my own dyno testing on the
track, I liked the injection not only
because of the response but also because
when you let off of them it’s like putting on
the brakes, they shut the engine down
now which allows you to drive it into the
corner deeper.
How else can we get more fuel into the
engine? Well, atmospheric pressure is 14.7
PSI, how ‘bout we up that? A Supercharger
will do that nicely but again, there’s more
to it than just bolting one on. We had a
fellow in the club who had a good running
Flathead and one night he showed up to
the track with this late model turbocharger
on. He had done a nice job, really. Cliff
Kotary was there that night and we went
over to look at it. I asked if he had used
forged pistons and the answer was no, he
just bolted it on and it ran great in the
driveway. We also noted that both exhausts
had been run together with a crosspipe to
power the turbo and then to the wastegate.
This engine is constipated in the first place
I thought, that can’t help. We walked away
taking bets as to how many laps he’d
make, I bet ½ lap, Cliff said maybe one. In
warmups he went like mad and we were
both wrong as he made a lap and ½. And
blew it to smithereens, he related later
that there wasn’t a piece of piston left in it
when he took it apart, a shame. You have
to plan for a blower in my opinion and if
you’re going to run appreciable boost, say
8 – 10 lbs., you’d better plan on forged
pistons first and the proper camshaft
second. A cam with a lot of overlap will
most likely just push fuel out the exhaust
so I would conclude you’d have to open up
the lobe centers. OK, so you’ve planned for
the blower, which one? My personal
preference would be the positive
displacement (roots) type over the
centrifugal (McCulloch) mainly because of
the fact that it’s better off the bottom of the
RPM range, the faster you turn it, the
more volume it puts out. I’m sure the
McCulloughs are OK at high RPM, one guy
ran one here in the 60’s and did well with
it for about 6 laps when the belts would
burn up, no thanks. Of the Roots type
there were several available, the
Italmeccnica and the S.Co.T were the early,
and now highly sought after units that
most used. Earlier examples were
converted from Benz or Pepco but they all
were basically the same design, two lobe
straight rotors placed in a tight fitting case
to pump air. The later designs such as
Camden, B&M and Weiand are of this
same basic design and all work quite well.
Another club member ran a B&M with
success in our club but ran into reliability
problems as the years went by. I stuck with
the injectors and moved them from engine
to engine, one thing I can relate from his
experience with blowers – they can get
expensive. RoadRunner engineering offers
a good kit today which has proven to work
quite well, H&H is offering the S.CoT. kit
again but  neither is what I’d call cheap.
For me the way to go is a GMC blower, a 4-
71 to be exact. Let’s see 4 x 71 equals 284
cu. in., that’s about right for the flathead
and it’s quite a bit bigger than the other
offerings, and they can still be had rather
inexpensively. The 4-71 differs from the
other designs in that it’s a 3 lobe twisted
rotor, more betterer. They have to be
rebuilt and reversed for the street or race
usage but Pat Ganahl’s book ‘Street
Supercharging’ goes through this nicely.
Now, you’ll need the intake. I’ve seen many
examples of modified intakes, mostly D&S
and I think the Fenton would be a good
candidate as well, mill off the tops and
weld an aluminum plate on top to bolt the
blower on, get a drive and presto! Easy
right! Barney Navarro had some
commentary on this as his intake has a
smaller opening than the 4-71 for the
purpose of creating turbulence. I talked
with a fellow from California years ago now,
Jack Miles was his name and he related
that many out there played with the intake’
s opening, making it somewhat of an
oblong triangle shape, they found that this
increased performance, probably along the
same lines as Navarro was talking in that a
blower at slow engine speeds is just
whipping up the mixture and pouring it
into the engine, you got it, puddling. He
left the ridges on his intake sharp to help
create turbulence and mix the air and fuel
better. Another design that is fairly recent
is made out of New Zealand made by
Mitchell. Again the opening is smaller and
the log area has been cast with ridges,
almost like fins to combat the puddling
issue. This intake was used on a fuel
dragster and posted what are supposedly
the fastest times ever in a flathead powered
¼ mile (although I wonder if they eclipsed
Rich Schnell or not – another 4-71 driven
fuel dragster). I also had some chat’s with
Bob McCray of California, another dragster
racer and he related that a 4-71 in race
trim should be driven 10% over crank
speed, keep the compression down to 6:1
or so, and my notes show him using a
spark retard as well. Plenty to think about,
if I ever get to one I’ll obviously know more.
Ok, so let’s dream a little – what’s the
ultimate inductions system? I mean of
course aside from Ron Main’s twin turbo
unit (see Flathead ‘Book of Death’ on our
links page). I’d say for circle track racing it’
d be the 4-71, with a flying toilet on top
and injector nozzles running to each port
in the manifold. Navarro’s and Mitchell’s
design’s both have accommodations for
this and in my chat with Barney several
years ago, this is what he suggested to
keep up with the GMC’s. Now, throw in the
crossfire crank, spark retard on the MSD
unit, 112 degrees between the lobes on
methanol and hope it stays together. We
can all dream right?
Back to reality, two deuces work well on
the street, my father’s hotrod has a pair of
94’s and they snap right up pretty quick.
Three deuces look cooler and I won’t say
they’re race only but a progressive linkage
would have to be a must in my book on the
street. On the track, 3 deuces work great, a
small Holley, Carter WCFB or early
Rochester Quadrajet also work well, and I’
m going to eventually find out about two
2G’s as well, they worked great for Cliff.
The injectors are great as well, the 4-71 is
gonna have to wait a bit, that’s Ok though,
it doesn’t eat much, at least not now..  
Go! With Edelbrock.
Stromberg 97 & larger 48.
Holley 450 on Fenton intake, a good setup.
Stromberg 97 and 48 throttle body's, slight difference..
Edelbrock tall two deuce was similar to Tattersfields design.
Rochester 2g.
2G's throttle body butterflies versus Stromberg 48, biggerer is betterer..
Winfield Model SR on adapter for Flathead intake.
Winfiled SR adapter throttle base.
4 deuce challanged injection in horsepower ratings.
Hilborn sticker.
Stu Hilborn's first injector.
Hilborns's 54th injector from 1952.
Early injectors followed the flathead's port angle..
McCulloch Sticker.
This turbo lasted 1 1/2 laps...
Stewart Warner pump  and Hilborn pump.
Centrifugal supercharger.
This B&M Roots type worked well when it stayed together.
GMC 4-71 Supercharger.
Mitchell 4-71 intake, note the injector bosses and corrugated floor.
4-71 mock up.
Pull the pin..
Carter WCFB and Offy 4 Barrel intake, a good setup.
Pine Tree road dyno..
Holley knows carburetors.
Don't forget the loud pedal..