Throttle Linkage Safety Shield
There have been a couple of reports from XJ-S V12 owners that the B bank
throttle linkage pullrod can get fouled by the low pressure freon hose from
the firewall to the fuel cooler. In the worst case scenario, the driver
floors the throttle and the resulting torque twists the engine on its mounts,
shoving the linkage up into the hose and jamming it wide open. Ungood.
This problem may be exacerbated by a failed motor mount.
The obvious solution advocated by some is to tie the hose to the diagonal
brace, which should hold the hose up and out of the linkage. There
are a couple of problems with this solution, however. First, if the
problem is the engine rising up rather than the hose dropping down, tying
off the hose won't help. Second, the engine will be moving around on
its mounts but the diagonal brace won't, so tying the hose down may stress
The book now contains a diagram for
fabbing a simple sheet metal shield that should keep the hose and the throttle
linkage from ever meeting. Here is a picture of such a shield installed
on Kirby Palm's '83:
That's the device in question to the left of the far end of the throttle
pullrod. It is bolted down under the heads of the upper two bolts that
hold the fitting assembly to the rear of the LH intake manifold.
The term "shield" may be misleading in that this device doesn't actually
sit over the throttle linkage. It sits about an inch aft of
the linkage. However, it effectively keeps the hose from fouling the
linkage because the hose won't bend sharply enough to go over this plate
and down into the linkage.
Note that this may not be a typical arrangement. Palm had new hoses
made up, and in the case of this particular hose he changed the configuration
a bit. The fitting that connects to the fuel cooler -- to the right
in this picture -- was originally a 45° fitting, but he went with a straight
fitting. The fitting at the other end (not visible) was originally
a long 45° fitting and he went with a standard (short) 45° fitting.
Finally, the overall length of the hose was reduced by about 1-1/4".
The end result is that this hose fits a lot better than the
original did -- but your hose may not be sitting in the same place as his.
If yours crosses the throttle pullrod more than a couple inches closer
to the centerline of the car than Palm's, the design of the throttle linkage
shield may need to be revised a bit.
There are a few unrelated things of note in that photo. That black
box in the foreground is the famous Lucas AB14 CEI ignition amplifier, which
has a common GM ignition amplifier module hidden inside. This is the
ignition system of choice to have on the Jaguar V12 -- no excessive proclivity
to get cooked, excellent performance, cheap to repair.
That brake fluid reservoir
is from a Mitsubishi. It is connected to the master cylinder by a conglomeration
of red hoses with reducers, necessary because the fittings on the Mitsubishi
reservoir are larger than the connections on the Jaguar master cylinder.
The fuel hose in the foreground has been replaced, and replacing involved
cutting off a cup surrounding the push-on hose fitting and reassembling it
with only the dished washer end of the original cup.
Partially obstructed from view is a blank-off cover where the cold start
injectors were originally intended to go. The cold start injectors
were deleted from the H.E. somewhere along the line, and sometime later they
ceased drilling the holes at all so these blank-off covers could be omitted.
The OEM cam covers are painted black. Palm's cam covers have had the paint removed
so they appear as bare aluminum.
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