Pertronix and vacuum leak info
08-12-2001, 02:20 AM
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Pertronix and vacuum leak info
I ran into a couple of interesting things today I thought I'd pass on to you.
My 72 has been running kind of ragged lately. This morning I pulled the distributor because I felt too much up and down slop at the cap rotor. Pertronix says the distance from the ring to the little box should be 010 - 040, and I could move the rotor up about 0.100" So I took it all apart and found that the magnetic ring was bent up toward the rotor attach screws. I evidently tightened these too much and actually bent the ring. So in rotor rotation the ring would touch the box, then open up the gap, then touch the box again.
I was able to take most of the bend out of the ring..but not all. So then I popped off the gear and slipped in 090 worth of shims to take out most of the slop. At reassembly I measured the gap from the magnetic ring to the box and found it to be 035 to 065. So I added shim washers at the rotor screws to get a gap of 015 and 025.
Once all was back in place, I hooked up the timing light and vacumm gauge. Vacuum was down to about 15 where it used to be 19 1/2. The leak was at the elbow coming from the power brake booster to the manifold. This elbow works like a PCV valve. :confused:
So a trip to PepBoys and the hardware store got a replacement made. It's running real sweet again. :D
Be careful with the Pertronix install, and vacuum leaks can come from anywhere. :eek:
My 72 has been running kind of ragged lately. This morning I pulled the distributor because I felt too much up and down slop at the cap rotor. Pertronix says the distance from the ring to the little box should be 010 - 040, and I could move the rotor up about 0.100" So I took it all apart and found that the magnetic ring was bent up toward the rotor attach screws. I evidently tightened these too much and actually bent the ring. So in rotor rotation the ring would touch the box, then open up the gap, then touch the box again.
I was able to take most of the bend out of the ring..but not all. So then I popped off the gear and slipped in 090 worth of shims to take out most of the slop. At reassembly I measured the gap from the magnetic ring to the box and found it to be 035 to 065. So I added shim washers at the rotor screws to get a gap of 015 and 025.
Once all was back in place, I hooked up the timing light and vacumm gauge. Vacuum was down to about 15 where it used to be 19 1/2. The leak was at the elbow coming from the power brake booster to the manifold. This elbow works like a PCV valve. :confused:
So a trip to PepBoys and the hardware store got a replacement made. It's running real sweet again. :D
Be careful with the Pertronix install, and vacuum leaks can come from anywhere. :eek:
