Re: Cam for my 440

Below are a few pearls I dug up from Don Dulmage regarding tuning dual carbs,
dual planes, vacuum and such. Sounds to me like he's a dual carb fan.

You might also have a look at the Dvorak Multiple Carburetor Syncronizer.
http://www.dvorakmachine.com/carb_sync.shtml

- Jim
Jim Altemose, Long Island, NY
'63 Polara 500 (Max Wedge)
'63 Polara 500 (383)
'65 Belvedere I (Street Wedge)
'71 Bronco

Vacuum and dual carbs:
Me ,I think that local speed shop guy should be shot and spit on.
Under 400 cubes a car with a vacuum secondary will almost always work
better than a double pumper. Why? Because that small an engine cannot
deliver enough low speed airflow to maintain a strong venturi signal
at low RPM. The only way around that is to install a tiny double
pumper like say a 650 which is ointless as it hampers top end power. A
good reworked 3310 will outperform almost anything you can find and
the mods required are simple and are covered in the book (old
reliable) Above 400 cubes a double pumper like say an 850 will do a
good job but on the street with milder gearing a vacuum secondary
carb would probably be a better choice. I passed up an 855 cfm holley
from a early big block corvette but now I wish I had bought it and
reworked it. We remove the choke housing and blend the top leaving the
vent tubes intact, we clean up any casting flash (with a sharp knife)
drill a small hole (.060 to .070") in the front throttle plates for
idle air bypass with a big cam so the throttle will be closed enough
to allow the idle circuit to operate properly. We jet up from stock 3
to 4 sizes and install a # 5.5 power valve.We reinstall the carb and
hang on!!!!!!
For vacuum secondaries we remove the check ball )i know i know but it
helps a lot to speed up seconadary reaction.) and we pull the stock
spring back through itself about half way and reinstal it. Works
great. A vac secfallows you to run a bit oversize carb with no low end
loss and better top end power.
AFbs Edelb or Carters. work great as well but dont have the bigger
sizes. However a pair of carters is a real ball to drive and easy to
set up. I know the factory came out with a single four for the hemi
BUT when set up right i am betting the stock set up would bury it.
Biggest trouble with the dual set ups is getting the Wide Open trottle
positions matched so they both hit full open at exactly the same time.
this gets rid of most of the problems and makes them work much
smoother.
Edelbrock marine carbs are exceptional for power. Seconadary weights
may be drilled to lighten them to speed up seconadary action for a
race car. (AFBs)
Don
Author of
Return to Deutschland (True Adventure)
Old Reliable (Mopar)

Tuning dual carbs:
Set both carbs as close as possible before starting. (Same number of
turns out from totally closed.) When it is tarted and warmed up and
cam thoroughly borken in (20+minutes above 2500RPM ) you can start
working on carb balance forst rough in the idle spped. Probably 900 to
100 would be good. then just go back and forth between each carb
trimiing the idle adjustment scews to get the smoothest idle (Smooth
is a relative thing.)it will never be smooth becuase tof the cam but
there will be a smoothest or best point. trim your mixture screws .
Turn each one in till it obviously upsets the idle then back it out
till it stabalizes. Keep going around the idle mixture screws then
back to the idle speed screws . Work back and forth till you get it as
good as possible at the idle speed you desire. A piece of garden hose
cut about 3 ft long is good to hold one end by your ear and listen
over each carb. It will give you a very good idea about where each is
compared to the other.
NO#1 trick with dual carbs is linkage. MAKE SURE they close and open
at exactly the same time. On the idle scew together and full open
together. That is the biggest trick. For years i tuned hemi cars for
people. Even with the inline fours this was the problem I found and
it would always cause bogging and not the best performance, Aside from
a straight type tune up I often had tp spend half a day or more
repaing and readjusting linkage, sometimes making small parts even to
get it right. The cross ram is similar. I have worked on both max
wedge and race hemi crossram set ups. The linkage is the big deal with
either.
So for you hemi guys if your ride is baulking a bit, this is where
the solution will be found. that and a step up in jets one size to
match modern fuel will really wake them up.
For everyone with dual fours , inline or crossram making sure the
linakge is right will solve most of your difficulties once you have
the idle adjustments right.
Don.
PS where do you start wiith the idle mixture screws?
I always start with them set at 2 1/2 turns out (5 half turns) this
works with almost any automotive carb and will get you in the bal park
so you can trim the idle from there to perfect. Dont get consumed
tough with how many turns it finally is. Just give it what it wants.
Don
Author of
Return to Deutschland (True Adventure)
Old Reliable (Mopar)

Dual plane vs. single plane:
Dual planes are essentually two four cyl manifolds grouped together on
a V*. They each feed from one side of the carb or carbs and make a
efffort to seperate the cylinders by firing sequence as much as
practical. This is good for torque and bottom end perfomance.
Single planes draw all from the same plenum and use runner length and
the availablity of all four barrels of the carb to make extra power.
They typically are not as torquey down low and midrange strong as a
dual plane.
However
The Edelbrock Perfomer RPM is a serious piece of manifold that has
huge port runners at the proper length with a generous plenum. It is
the best of both worlds and a cut above most other manifolds. It is
particularily well suited to our engines in traditional tune . It does
not belong in the catagory of "just dual planes" but is a cut above
(make that a thick slice above. )
If we could get Vic and his Daughters to make us a 2X4 set up with a
Performer Rpm design then we would really have some fun.
Food for thought though Many 273s and 318 were single plane from the
factory in the early years of the la motors so a single plane can be
made to work down low with small runners to speed up velocity. (Port
velocity helps torque. )
The Max Wedge single 4bbl (Yes Virginia they really did make them and
I have one) was originally built in a single plane then came the rev2
manifold that is a dual plane and a very well designed manifold. It
was said at the time to be 14 HP over the single plane design.
The single plane is not always the best set up. It depends on what you
want the engine to do. Our engines have strong midrange and bottom
end with a respectable top end . The competition has very little
botttom end grunt and a so so midrange, They are more of a top end
motor so when you are building a B wedge to compete it is wise to
concentrate on what makes these engines great. and to build your combo
around these unusual charcteristics. Otherwise it is like trying to
make Merle Haggart an opera singer. (Like Why ruin a good thing?)
Build on strengths is my motto. A well set up Mopar wedge can have the
race won long before the bowtie begins its charge. Then all you need
is enough HP to hold him off up top. I am talking about stock based
iron headed stuff here by the way not the megabuck superflow 300cfm
plus hidollar setups
Don
Author of
Return to Deutschland (True Adventure)
Old Reliable (Mopar)

Well me i would go with the largest average HP. Lets pretend it was
money. Would you rather work for 800 dollars per weeks with one pay at
the end of 1200 or work for 900 per week steady.
Hp is the same. More average HP means the engine does more work. More
work means better performance , lower ETs. however on the right type
of engine with a high duration roller cam , huge cylinder heads and
little need for bottom end power in a light weight car then the new
440 intake would get the nod.
BTW one of the great things about a perfomer style intake or most
dual plane intakes is that it solves a little problem with firing
oder.
18436572 57 which are side by side in the engine drivers side rear
corner. fire one right after the other. This places a lot of extra
demand on this section of a single plane manifold and that back corner
barrel of the carb. You may have noticed the chevy guys now have new
cams for their engines that change this firing oder (Chevy normally
uses the Chrysler firing order) and swap cylinders to eliminate this
little quirk. We have no such option yet although we have asked for it
off and on more than once on the last 10 years or so. However, The
dual plane manifold does away with this problem by plumbing 5 and 7 to
opposite sides of the intake , something the single plane cant do.
Does that make a big difference? It is hard to say but it is something
to think about. The Perfomer RPM manifolds are the best of both
worlds and there was a tremendous amount of work put into especially
the 440 one. It is no wonder it works so well.
Don
Author of
Return to Deutschland (True Adventure)
Old Reliable (Mopar)