Way back when Holley first announced their bolt-on stand alone EFI system, I asked them if they had given any thought to a 2 X 4 set-up. They told me it was likely six months away. When I went back to them, they'd decided not to do it. I was writing for Super Ford Magazine at the time, and after some discussion they agreed to help me with a 'two-complete-system' application. I made use of Brother Lon's 427 SO/MR combination in his '67 Mustang.
We installed two of their 900 CFM packages, keeping everything separate except to use a single fuel delivery combo with two fuel pumps in parallel, and a 'Y' in the engine compartment to feed two throttle bodies.
We did the ultimate testing sessions on the half-mile-track at T&C Livonia, using an accelerometer for instrumentation. The first tests showed that it was impossible to have good street manners and max performance at the same time. Discussion with the Holley engineers resulted in a substitution of lower capacity injectors to get things within the adjustment limitations of the electronics package.
The result was a much more docile engine for DD-type purposes---although it was purely a 'cruise-night' car at the time. But we also achieved a very significant reduction in such things as 20-to-80 times.
I did a couple of articles about Lon's Mustang for Super Ford and later did other write-ups regarding Holley EFI for a couple of other magazines as well.
There was really no down side to the change. I'll never be satisfied with a carburetor-equipped set-up again!
KS
