4.5 engine vacuum

[Litton]

All of a sudden, I seem to have lost my vacuum retard for the the distributer. I don't have a vacuum tester yet so I am going to go out and pick one up.

I noticed it when I was adjusting the timing after installing the Pertronix stuff. I pulled the tubing off both sides of the valve and connected them togeather but nothing.

I have found three location for vacuum on the engine.

First is the throttle body for the distributer retard.

Second is the brake booster.

Third is right beside the brake booster connection which is used for (I suspect) the central locking system and the trans. modulator.

Typically the trottle body vacuum is much less then manifold vacuum (also a bit independant of it) so I am wondering if I have screwed something up or did my retard unit bite the dust when I was moving it manually.

Does anyone have a clue as to what the vacuum at the T.B. should be at idle? Also, which port is best to check manifold vacuum? The locking system is probably the easiest to get at.

P.s. The locking system seems to work. Does about 3 lock/unlocks after the engine is off.

[Litton]

Update......checked vacuum at idle, show 15 mm. Checked the retard unit with a vac. pump.....works fine. Used vac. pump to actuate the module while at idle....no change in timing. Centrifical advance works fine....about 30 deg at 2500 rpm.

Called Pertronix....they're puzzeled and will talk it over and get back to me.

So far I have driven the car about 2.5 miles since I bought it but I am having fun.

[psfred]

Litton:

Did you manage to dislodge the actuator linkage for the vac retard in the distributor? Thats the only thing I can think of that will cause the actuator to work and not advance the timing -- the plate in the dizzy rotates, so it will move the Pertronix pickup just like it did the points.

You can run without it, just set the timing to 7 BTDC rather than 5 ATDC.

Peter

[Litton]

The actuator moves just fine. Plate is moving just as it should. Using my newly aquired vac pump, I watched it move at ~ 6" of vac. Very strange. Pertonix is also very interested in this problem and hopefully they will have some input later today.