The stage 2 modification has an additional 7/16" diameter restrictor
placed in the front port of rear water manifolds and specifies an increase
to 1&1/8" for the outer diameter of the front to rear connecting pipe for
users of fuel injected water manifolds.
Interesting. There are only two ports at the back end, one is being
reduced in size, and yet the pipe that connects this manifold to the
front end must be enlarged? Seems as though the OEM pipe shouldn’t
be much of a restriction to flow.
The photo shows these larger pipes and the manifolds all welded
together. I really don’t like that idea. The OEM arrangement of the
pipes mounted in rubber allows everything to flex, such as when the
engine heats up. Even if I were convinced that a pipe enlargement
was called for, I’d be looking for a flexible way to do it. One idea
might be to weld pipe stubs onto each manifold and connect them via
some hose. A neater fix might be to fashion O-ring grooves into each
end and slide a pipe into them during assembly so the O-rings seal
against the pipe while it is trapped between the manifolds.
For racing, a stage 3 modification is to use the earlier (but modified to
stage 2) carburettored water manifolds in place of the later fuel injected
design, incorporating the wider joining pipe…
I guess I don’t understand this. Do you switch to the carb style
water manifolds BECAUSE they have a wider joining pipe, or you
incorporate the same wider joining pipe as in Stage 2? What’s the
advantage of the carb style manifold over the EFI version?
and a smaller water pump
pulley of 110mm diameter. These are already fitted as standard on a v12
etype.
So, you’re spinning the pump faster? See, from some earlier messages
I thought it was the CRANK pulley that was smaller on the E-Type,
which would mean the pump turns slower. Faster sounds better to me;
I’ve always kinda suspected that thing turned too slow, especially at
idle, and especially if the idle is too slow – which is easy to get
on the Jaguar V12, it’ll idle smoothly down to 300 and even slower.
On my '83, I replaced the pump impeller with one from a Chevy. It
fit just fine, and truth be told the only reason I did that was
because I had accidentally damaged my original Jaguar impeller.
However, I really liked the Chevy impeller better; it had very
slightly rearward-inclined vanes, almost radial. The Jaguar impeller
has radically rearward-inclined vanes, so far laid back that I’m not
convinced they move coolant well at all – at least, not unless
they’re really moving fast. So, given the OEM impeller, I’m
certainly inclined to agree that speeding that thing up is liable to
help considerably.
I still would do those orifice mods with little shims instead of
plugs.
– Kirbert
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