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| Joined: | 03-12-2005 |
| Location: | Kingman, Arizona USA |
| Posts: | 532 |
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You will need to remove the air box or aftermarket filters from the two carburetors, and to disconnect the vacuum line running from the engine to the black plastic carbon cannister that attaches to the front of the battery bracket. You should then have fairly easy access to the distributor.
The next step is to pop off the distributor cap. This is easily done by inserting a flat-blade screwdriver between cap and flat spring clips, then twisting the screwdriver so the clip snaps free. There are two spring clips and both must be undone. The cap may then be gently tugged free and moved out of the way.
With the cap off, the distributor rotor is visible. NOTE WHICH WAY IT POINTS! Also note the orientation of the distributor body. You will need this information when you put the distributor back into the engine. Make notes or sketches, if necessary.
If the points are in place, there is a blade connector on the side of the distributor, and a wire (often but not always black in color) that runs to the (-) side of the coil. Disconnect this wire from the distributor. With the Pertronix unit, there should be a red wire and a black wire coming out of the distributor and connecting to the (+) and (-) sides, respectively, of the ignition coil. Both of these need to be disconnected.
Disconnect the vacuum hose that attaches to the spigot on the vacuum retard capsule (the disk-shaped thing) on the distributor. Plug this line with a golf tee or something similar.
Now examine the distributor. A stepped metal plate is attached to the bottom of the distributor by an integral clamp. Do not disturb or undo this clamp. You will find a small (metric) locknut at the end of the plate, that is attached to a stud coming out of the casting into which the distributor fits (this is the oil pump). Undo this nut and place it in a safe location. The distributor may now be pulled directly to the rear and removed from the engine for whatever work needs doing.
I've attached a photo showing the insides of a JH distributor. If you're reinstalling the points, apply a tiny amount of points grease or dielectric grease to the fiber or plastic arm that contacts the cam in the center of the distributor. Be sure to set the points gap to 0.014" to 0.016" when the points are fully open.
Remove the rotor, add a drop or two of motor oil to the cavity beneath it, then reinstall.
If the o-ring installed on the tubular section of the distributor is worn or damaged, you may wish to replace it at this time.
Orient the rotor relative to the distributor body as noted during removal, then slip the distributor into the engine. Do not force things. At about the time the hole in the stepped metal plate slips over the stud on the oil pump, use one hand to rotate the rotor back and forth a little while using the other hand to continue pressing the distributor into the engine. You will encounter a fairly strong spring force, and will find a spot where the two blades of the drive dog (the fitting on the end of the distributor) slip into the mating slot inside the engine. Once certain the blades have entered the slot, press the distributor the rest of the way into the engine and secure it in place with the metric nut.
Reconnect the wire from coil to distributor. Double check to ensure that the rotor is pointing the same way as it was when the distributor cap was first removed.
Next, coarse-set static timing. Turn the ignition switch on to the RUN position, and connect a voltmeter or test lamp from the (-) side of the coil to chassis. Ensure good electrical connections. Loosen the clamp bolt (not the metric nut) on the stepped plate at the base of the distributor. Rotate the body of the distributor clockwise as viewed from the front of the car until the trouble light is not illuminated or the voltage on the coil's (-) size goes to zero. Then carefully rotate the body of the distributor ANTI-clockwise as viewed from the front of the car until the trouble light just illuminates or the voltage on the coil's (-) side rises to anywhere between +3V and +12V. Only a relatively small rotation should be necessary for this -- certainly much less than 1/4 turn.
Repeat the above several times until you have a very good feel for the point at which the light just comes on. Then, with the distributor remaining at that point, tighten the clamp bolt. This should set the static timing to a point where the car will start and run.
Reinstall the distributor cap, ensuring as you do so that the rotor is pointing toward one of the turrets on the cap. Snap the two spring clips back into place. Check to ensure that the wire from distributor to coil is still in place. Remove the voltmeter or test lamp.
Start the engine and let it warm up. Once the engine has stabilized at an idle speed of not more than 1000 rpm, use a timing light to set dynamic ignition timing to the preferred point (the factory 'low-emissions' setting is 8^ before TDC [BTDC], while best performance is typically at about 12^ BTDC) using the little knurled wheel on the side of the distributor body. If this wheel does not have sufficient range to permit reaching the desired timing, set the wheel to its physical midpoint, loosen the clamp bolt at the base of the distributor, rotate the body of the distributor until the desired point is reached, then re-tighten the clamp bolt. Any fine-tuning can now be done with the knurled wheel. When satisfied, shut off the engine, disconnect the timing light, reconnect the two vacuum hoses, and reinstall the air filtration system.
And that's it. You should now have a JH that runs properly, and will have earned a bit of knowledge about the car.
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