Replacing the needle valve on SU Carbs with Grosse Jets is one of the easiest tasks you could ever perform on an E-Type, and is something that all E-Type owners should do, many fires can be attributed to a stuck needle valve.
Before you remove the carb parts, go ahead an order new Gross Jets from a Jaguar parts supplier. A Gross Jet is simply a valve that uses a ball on a circular seat. Unlike a needle valve that can become stuck in its chamber, the ball on a Gross Jet cannot. As the float in the gas chamber rises, it will eventually meet a two-pronged fork. As this fork rises, it will push against the small ball, forcing it to seat and stop the flow of gasoline.
In addition to the Gross Jets, I would also order the 3 small seals that go between the reservoir top and the chamber, as well as the 6 fiber gaskets that go on each side of the banjo bolts in the fuel supply manifold.
All of these pieces will become apparent as you take the tops off of the fuel bowls. There are also special seals under the 3 center bolts…keep these in order!!!
The rest is fairly simple. Drift out the hinge pin on the fork piece and remove the fork. Unscrew the old needle valve and throw as far as you can. Screw in the Gross Jet, not forgetting the little reddish gasket. Re-assemble the fork piece. As the directions will state, use a 5/16” bolt or drill rod to check the distance of travel before the GJ seals….you don’t want it to shut off too soon, or too late. If you don’t have a manual that explains this, then you need to add THAT to your order from the parts house as well (get the Bentley’s Official E-Type manual).
Check the bottom of the reservoir for dirt and/or rust. If it’s pretty dirty, then you may have an issue with your gas tank…but that’s another problem for another post. (If you’ve never done so, pump out all the gas in your tank and un-screw the sump under the car…it could be full of all kinds of nasty, car stopping stuff!!!)
Reassemble everything and CAREFULLY tighten down the banjo bolts. That reservoir top is very thin and brittle, so just make sure everything is snug as opposed to really tight….otherwise you’ll break the top. Turn on your ignition and listen to the purr of your fuel pump. When it slows down and hopefully stops, check all the fittings for leaks and drips, and snug up where necessary.
Piece of cake!!!