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Intake Manifold Modification
The simplest intake manifold option for a fuel-injection
conversion is a modified single-plane carbureted manifold.
Shown is a 302 Victor Jr. modified for injectors by Mass
Flo EFI. They can do this on a Cleveland manifold
as well. We'll be using their system in our own EFI conversion
project. |
In an EFI system fuel is added directly to each cylinder via
individual fuel injectors mounted in the end of each intake
manifold runner. Because a fuel injected manifold does not have
to provide the signal to the carburetor for proper air-fuel
metering, fuel injected manifolds have different design objectives.
However it turns out single plane carbureted manifolds and fuel
injection manifolds are fairly similar in design; both use individual
runners drawing off a common plenum. Thus many guys converting
to fuel injection opt to simply modify their carbed single plane
intake for injectors and then run a modified "four barrel"
throttle body to fit the carburetor flange, or an elbow that
allows the use of a late-model Mustang throttle body. The drawback
however is the single plane has significantly shorter runner
length, which will hurt bottom end torque. While not a concern
in a high rpm application, it certainly could put a street car
at a disadvantage.
It is for this reason that Tornblom just wanted a true long-runner
EFI intake. Most of you are going to look at the route Thomas
Tornblom convert his Cleveland to EFI and conclude that it
is simply not worth the trouble. However we think it is interesting
how Thomas did the legwork in adapting a 351W manifold to
a Cleveland block
Shown is a 351C carbureted manifold (this happens to be
a Holley Street Dominator.) Note, unlike on a Windsor
block, the Cleveland manifold does not have a thermostat
housing cast into the front of the intake. The manifold
is also a bit narrower due to the Cleveland's shorter
deck height. |
Trick Flow 351W EFI (lower manifold shown). Note the horizontal
manifold bolt holes and thermostat housing. Windsor engines
route coolant through the front of the manifold (and rear
on some). The manifold is also .300-inch wider than the
Cleveland intake. |
Adapting a Windsor manifold to a Cleveland
block turns out to be less of a nightmare than it sounds like
it should be. First is the issue of manifold width. The Cleveland
deck height (crank centerline to top of deck) measures 9.206"
compared to 9.503" for the 351W ('71-'95). The wider
Windsor manifold needs to be flat-milled approximately .150-inch
along the sides to fit between the Cleveland heads.
Placing the stock Cleveland intake valley pan on the Windsor
manifold shows where the manifold needs to be modified.
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On Windsor engines coolant flows through the
front of the intake and cast-in thermostat housing. Cleveland
manifolds do not have water flowing through the intake and
the thermostat is mounted in the block. The Windsor manifold
this needed to have the front thermostat housing chopped off
and welded up.
Similarly, at the back of the Windsor manifold, the PCV location
needs to be cut out to match the contour of the Cleveland's
intake valley and also allow clearance for the Cleveland oil
pressure sending unit.
The underside of a Cleveland intake manifold. Note the
shapes of the end rails and lack of coolant ports at the
ends of the intake. |
The Windsor manifold will require hacking off the rear
PCV and baffle along with the front thermostat housing.
The end rails will be reformed. |
The rear of the Windsor manifold has been cut and modified.
Extra aluminum is TIG welded, shaped to match the Cleveland
end rails.
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The thermostat housing has been cut off the Trick Flow
manifold and a new front rail shaped. The manifold is
then milled to ensure a flat sealing surface. |
The rear of the manifold now clears the oil pressure sending
unit and seals properly to the Cleveland block. Also note
the horizontal bolt bosses on the Windsor manifold have
been ground down and drilled at the angles necessary to
mount to the heads. |
The front of the modified TFS 351 Windsor manifold now
clears the Cleveland's existing thermostat housing location. |
Thomas used the Cleveland's valley pan as a porting template
for shaping the Windsor's rectangular ports into the oval
shape of the Cleveland head. |
The final steps of converting the TFS Windsor intake for
use on a Cleveland are to address the ports and bolt holes.
Both engines use twelve manifold to head mounting bolts, and
the center four on both the Windsor and Cleveland manifold
are horizontally oriented. However the remaining ten are angled,
and the angle is not the same between the two engine types.
Thomas solves this by grounding down the bolt hole casting
bosses and then re-drilling (See image 9.)
The final step is to port match the Windor's rectangular ports
to the oval ones on the Cleveland head. Thomas used the intake
valley pan as a guide. The TFS 351W lower has plenty of material
to enable the ports to be opened
up to the larger Cleveland shape.
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