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| Joined: | 04-14-2005 |
| Location: | Columbia, South Carolina USA |
| Posts: | 156 |
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The vacuum capsule is one of two types: it either advances the ignition timing when you open the throttle, this type works off of 'ported' vacuum meaning there's no vacuum applied at idle but as you open the throttle the advance unit now gets vacuum. This type will have a hose going to the carburetor in the area of the throttle plate.
Or there's the 'retard' type, this one has vacuum at idle and retards the ignition timing. When the throttle is opened, the vacuum drops and a spring inside the unit now advances the ignition timing. This type will have the hose connected directly to the intake manifold.
Either one can be bypassed but now you have to set your ignition timing differently: the engine has to be run at ~2500 RPM and the ignition timing set at the full advance point. I'd have to go back and look at my manual, but I believe that's 32 deg BTDC. This means the ignition timing at idle will be advanced compared to the stock setting.
The mechanical advance is a set of weights and springs inside the distributor, under the points plate. It looks like this:
http://i198.photobucket.com/albums/aa70/supercharged111/Crown%20Vic/DistributorMechanicalAdvance.jpg
Here's how to install the distributor holddown to make life a lot easier. I learned this from messing with MGBs which have the dizzy clamp in a terrible spot (although nowhere near as bad as the J-H's): while you have the dizzy out, install the clamp on the dizzy and experiment with the clamp bolt torque until you can turn the distributor in the clamp with medium effort. It has to be tight enough that the dizzy can't be easily removed from the clamp, yet it can be rotated; as noted this takes some experimenting. Once it's back in the engine use the stud/nut which points toward the rear of the engine to hold the dizzy in place. Now you can turn the dizzy to set the ignition timing without having to loosen/tighten the bolt. In the future if you have to remove the dizzy, take the nut off of the stud and leave the clamp attached to the dizzy.