I started working on a 5.0 truck lower manifold (it has the larger runners
like the Edelbrock or Holley EFI manifold) but I haven't had much time to
make progress on it. I redrilled the injector bosses to drop the injectors
about 3/8" further down in the manifold, and then milled 3/4 inch off the
upper flange. The whole point of all that was to give the #7 and #8 runners
a way out from under the cowl, and then also to lower the fuel rails enough
to get them out from under there, and to let the upper part of the manifold
spread out over the fuel rails.
The big issue with the Ford EFI manifolds is that the last couple of runners
will interfere big time with the body. The lower-to-upper flange on these
manifolds is biased towards the rear of the engine by about an inch if I
recall correctly, and that actually gives airflow problems for the front
cylinders. If you were redesigning this setup from square 1, I'd start out
with closer to equal-length runners in the lower half of the manifold, and
make sure that the lower-to-upper flange was far enough forward to clear the
Tiger firewall and reinforcing rib on the firewall. I took some measurements
on this when I worked on it last and did up some dimensioned sketches of the
critical interference points, relative to the intake manifold port
locations. I can export them from Visio to GIF or whatever if you like.
Theo
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