Where does this go

What is this jaguar lucas part for

Part JS399, the Lucas distributor vernier adjusting screw.

~Paul K.

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The bottom of the Vernier adjuster has an offset pin (not visible in the parts diagram Paul has put up).

Unusually, this distributor has a 2 piece body. The dished part can rotate on the bottom part.

The threaded portion goes into the hole in the lug on the dished section of the dizzy body.

The pin locates into a slot on a lug on the bottom section of the dizzy body.

When the two body parts are fitted together it gives you a couple of degrees of Vernier adjustment by rotating it using a screwdriver in the slot on the top.

When you have achieved the desired rotation you lock it down with the nyloc nut while holding it in place with the screwdriver.

This adjustment is independent of the three Allen head screws (#10) which hold the base. You use them for coarse adjustment and the Vernier for fine adjustment.

The sprung slotted screws provide resistance to rotation of the dished section and locate it positively onto the bottom body section, but they are not screwed down tight, so you can use the vernier.

PS thanks for the part number Paul; I’ve been trying to find one for ages!