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| Joined: | 03-12-2005 |
| Location: | Kingman, Arizona USA |
| Posts: | 532 |
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Reportedly, installation of a Pertronix gadget often results in a radical change in the static timing, so most likely you will need to loosen the clamping bolt and rotate the dist. body to get the correct static timing. Frequently the vacuum capsule will contact the engine and prevent this. If so, you may need to rotate the distributor 90 degrees, which in turn will require relocating the four spark plug wires in the distributor cap. And even if none of this occurs with your car, you'll still have to re-set the timing once the engine is running again.
The hole in the clamping plate for the oil pump stud should indeed be slightly oval, but the oil pump stud itself is supposed to be 6mm in diameter, and its nut 10mm across the flats. If not, you may want to examine the oil pump in detail with an eye toward discovering whatever other peculiar things a PO might have done.
The knurled knob attaches to a threaded shaft (standard right-hand threads) whose other end is affixed to the body of the vacuum capsule. A spring surrounds the shaft, and a sheet metal curlybracket-shaped detent spring prevents undesired rotation of the knob. The vacuum capsule's diaphragm, in turn, is connected to the distributor's moving (points) plate by a long spring.
While the knob is often a little stiff to turn by hand, it should not be frozen. Possibly it's just screwed all the way to the end of the threads on the shaft, or there's some corrosion somewhere, either associated with the vacuum capsule, or with the moving (points) plate, or both. This needs to be looked at, as otherwise you may have unexpected timing changes that in turn cause peculiar performance problems or, worst-case, engine damage.
If desired, you can remove the vacuum capsule by (a) applying a bit of penetrating oil to the various moving parts, (b) using a pair of needle-nose pliers to carefully move the end of the long spring free of the points plate, then (c) unscrewing the knob (anti-clockwise) until the vacuum capsule falls free of the distributor body. When you reinstall the capsule, turn the knob until it's about half-way down the threads of the shaft. Once the ignition is static-timed, the knob can then be used to mke fine adjustments to your ignition timing.
Finally, any discussion of a JH distributor should touch upon the oil leak issue. The o-ring on the distributor shaft spigot must be replaced periodically. All available replacements are in the original standard inch-based size. Due to owner complaints about oil leaks, the factory later changed this to a slightly larger o-ring in some odd metric size that AFAIK is not currently manufactured anywhere in the world. There is also a shaft oil seal at the top of the distributor spigot, and this also can wear out and permit oil leaks. A better-than-factory replacement for this seal is commonly available for US $2-$3, but its installation requires disassembly of the distributor.
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