|April 28th, 2006, 10:04 AM||#3|
I am the law.
Join Date: 11-05-05
Location: Birmingham, Michigan 48009
BTW, the point of me making this thread is that you don't necessarily need to go out and spend $ on an intake and a 600cfm 4-bbl when you can have one of these for much less and enjoy all the benefits of the 4100's design (good on hills, etc). The 4300 is a 2-bbl and the 4300D is the spreadbore 4-bbl. here's some data from a Detomaso mailing list (Ford applications). They make an interesting comment about Holley intakes being able to accept the spreadbore carbs.
Motorcraft 4300 and 4300D
Ford replaced the Autolite 4100 with the Motorcraft 4300 and a spreadbore
version, the 4300D. Most 4V
Clevelands were fitted with one of the Motorcraft units. Both the 4300 and
4300D use air valve secondaries
with fixed jets and power valve enrichment. The 4300D has the standard
Holley/Autolite bolt pattern which
is unusual for a spreadbore and means they will not directly mount up to
most spreadbore manifolds, other
than factory Ford intakes. The only aftermarket intake manifolds that I'm
aware of that will directly mount a
spreadbore 4300D are the Holley Street Dominators and Strip Dominators.
They have a trapezoidal plenum
opening that will clear the large secondary butterflies. However, other
intakes can be made to work using
an adapter spacer.
Model CFM Venturi Diameter Bore Diameter
primary secondary primary secondary
4300 441 1 ?? 1 7/16 1 9/16 67-68 302 J-Code
4300 470 1 ?? 1 7/16 1 9/16 69 351W
4300 595 1 1/4 ?? 1 9/16 1 11/16 69 390 S-Code
4300 600 1 1/4 ?? 1 9/16 1 11/16 70 351W, 351C
4300 605 1 1/4 ?? 1 9/16 1 11/16 71 351C
4300D 715 1 1/4 ?? 1 9/16 2 71 Boss 351C,
4300's have a reputation of developing leaks at the front of the carburetor
between the lid or air horn, and
the main body. If you plan on modifying your engine, remember the selection
of power valves is very
limited so it will be difficult to tune properly. Also, there are no books
on the market for modifying or
performance tuning the Motorcraft carbs. Your best source of information is
a Ford factory repair manual.
Jack DeRyke thinks they are an instrument of the Devil :-)
Only the early model 4300's have adjustable secondary air valve. The
adjustment procedure is:
1. Loosen clamp screw and let housing rotate to no load position.
2. Hold air valve in closed position.
3. Scribe reference mark.
4. Rotate nylon spring housing counter-clockwise the proper number of knobs
and then tighten screw.
5. For 1967-1968 applications the proper number of knobs are:
289 manual 5 knobs
289 auto 4 knobs
390 7 knobs
410-428 8 knobs
Last edited by PävementPounder; April 28th, 2006 at 10:06 AM.