Chris Vaught wrote:
> Thank you
> Chris
Chris,
You are very welcome.
I know that you are new to the Tiger game, and I provided some additional
information on vacuum vs. mechanical secondaries, and how to get center hung
float
bowls on vacuum secondaries. While this wasn't your primary question, it will
be
coming up when you get there. There are lots of arguments on the benefits, and
drawbacks, of each basic type. I am sure you will hear all sides.
In your consideration of manifolds, I realize that there are a lot of opinions
out
there. When it comes to fit and dimensions, there are even more. While I
provided a response to your concern, it occurs to me that others may want the
actual dimensions to do their own assessments. When I was going through the
same
process as you are I contacted Edlebrock and got the EXACT answers. The F4B
information is not readily available, but I was able to locate a Vice President
who was in the technical department early in his career, and still had the
drawings for the F4B.
First, definitions of measurements:
To ensure adequate hood clearance, Edlebrock provides manifold heights for all
their products, but sometimes leave them out of the catalog by mistake. These
dimensions are made with the manifold sitting on a flat level surface.
A straight edge is laid across the carburetor pad mounting flange, and the
vertical height from the flat surface to the long straight edge are made at the
front center of the manifold. This height measurement is called "A".
A similar measurement is made at the rear center of the manifold. This
measurement is "B".
The carburetor pad height "CH" is simply A + B divided by 2.
Please note that these statements are valid under two conditions. First, the
length of the manifolds being compared is the same. Since they all fit the same
sealing surface on the same engine, this is true. The second criteria is that
the
carburetor mounting flange is located in the same position on all compared
models. This statement has been a subject of differing opinions on this list.
According to Edelbrock, The carburetor pad on the Performer 289/302 low rise,
the
Performer RPM, the F4B, and all other's for this block are not only the same,
but
are centered in the middle of the block, and directly over the exhaust
cross-over
in the manifold. These provides even heat under the carburetor, and is in a
fixed
location on the engine. While certain carburetors may be too long to clear the
firewall, at the same "CH", that effect will exist on all manifolds near the
same
height. The exception, of course, is the F-28 Dual Quad, with TWO four barrel
carbs, but they are symmetrically spaced.
Hear are the Edelbrock dimensions:
F4B (2500-7000 rpm design)
A = 4.563 inches
B = 5.313 inches
CH = 4.938 inches
Performer 289/302 (idle-5500 rpm design)
A = 3.50 inches
B = 4.75 inches
CH = 4.125 inches
(This is a 'low rise' manifold, similar to the stock Ford dimensions.)
Performer RPM (1500-6500 rpm design)
A = 4.30 inches
B = 5.50 inches
CH = 4.90 inches
As can be seen, the RPM is 0.038 inches lower than the F4B, giving more hood
clearance, although the F4B will fit if you don't use a carburetor higher than
the
Holley or Edelbrock. Carburetor choice, gasket thickness, thermal barrier
spacers
and needs for PCV tube plates alter the total height, but would add the same
amount to any.
The F4B is listed as a higher rpm manifold than the 'RPM'. Although, the RPM
is a
more modern design, flows better, and is of a higher quality casting and
material. If you are REALLY going to operate in the higher regions, perhaps a
Victor Jr., with an RPM range of 3500-8000 rpm, and a CH of 5 50 inches, or
Victor
5.0 with a really big 8.25 inches is worth considering for racing.
There are other manifold manufacturers, who make excellent products that may be
a
better selection for your application, but the questions were on Edelbrock.
Well, I suppose that's a good deal more than you care to know, but there may be
others on the list who do not have this information. Especially the old F4B
design. I hope it is of some use to someone.
Steve
--
Steve Laifman < Find out what is most >
B9472289 < important in your life >
< and don't let it get away!>
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