Hi,
The short answer to your question is that the wide-port spacing IS the PI
head. Your buddy with the TR250 will have to get a new head to go to PI
(unless he has a late head on there already).
I am not an expert on early/late Lucas PI, so I cannot comment on that
aspect. My suspiscion is that they used different metering units in which
case you can probably interchange the entire units as a unit (not mix and
match).
That said, probably the best thing you could do would be to use the
manifolds and throttle bodies and then convert to modern fuel injection
(with a computer). That's the best of both worlds.
The Lucas PI is pretty finicky and rebuilding the components is expensive.
The main drawback to the Lucas system is that the fuel pressures are in
the 100 psi range. Modern systems do the same work at lower pressures
(typically under 50 psi) so fuel leaks are much less of an issue.
The other drawback to the Lucas PI is that the metering is mechanical.
Much like a cam grind specific to the task, you have to re-shape the
metering cam to get power out of the system. There's a few folks that have
followed the Kastner / Ferstenau / Whoever pattern for better metering,
but you have to do precision grinding on the part (I've heard it referred
to as the "snail").
At any rate, modern computer-controlled fuel injection can be tuned a LOT
more easily, so that should be something to think about. If _I_ were doing
the job, I'd use the Triumph packaging (intake manifold, throttle bodies
and air cleaner assembly) and modern injectors (direct port IR style) and
a computer that allows you to change the fuel maps. That way it looks
vintage but you can tweak the crap out of it.
The last take-home on this one is that the power that the early PI cars
got was due to the 9.5:1 compression ratio and the fairly agressive cam
(290 degrees). If you're looking for power, consider the complete system,
not just the induction.
regards,
rml
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