Packard Forum Index » Pre-War (1899-1942)

Greetings,

When I adjust the timing on the car, I've heard of two different methods. One is to disconnect and plug the vacuum line to the distributor and the other is to leave it attached.

Any help would be greatly appreciated.

Before you start reference the service data under Section 8, page 63 of the service manual available on this site.

400-450 rpm with advance connected.

Accurate results depend on carefully locating and marking the dampener/pulley.

However, sometimes those dampeners aren't exactly accurate when they are old. Thus, as a pre-check connect a test light to the distributor, line up the timing marks and rotor, then rotate the distributor clockwise until the light goes out. If the stroboscopic timing is near the mark then the dampener is okay.

Do not rotate the motor counterclockwise to line up the marks. Only clockwise.

Next, when the engine is running connect a dwell meter and raise the rpm. The dwell should be stable. If it is not, then the distributor bushing is probably worn and needs to be reconditioned. This problem will cause spark knock and overheating. Sending the unit to somebody who has the SUN distributor machine can determine if the problem is easy to fix, or if there is wear in the camshaft system.

If you are having this problem, then perhaps you should do this test first.

If everything is set properly the motor will start immediately.

If the idle is set just a little high then vacuum will be directed to the vac advance and you will get a false reading. So especially on an engine where many and unknown hands have diddled it is a good idea to disconnect the line. There is no need to plug it. Then with the engine idling slowly so that the centrifugal advance is not kicking in you can set your timing.

I have had cars in where the timing was set massively retarded because the idle was high and both the centrifugal and vac advances were operating when the baseline was set. They will run hot and have no power.

Hi,

Thanks for the info but I could not find the file with the 60+ pages. I found a couple of files with about half the number of pages on tune ups.

Gene

Look in the literature archive for 1955 and you will find the Service Manual. Use Section VIII - electrical.

The reason 400-475 rpm is specified is because that is below any advance. The vacuum advance operates on ported vacuum which is inactive when the throttle is that far closed. That can be checked with a vacuum gauge which should read zero. However, if you disconnect it at the distributor you risk cross threaded because the line bends when you change the timing. Higher rpm also can affect the mechanical advance, so you really need to use a tach/dwell meter.

The reason I like to set the initial timing using the test light method (besides the fact that it makes rebuilt engines start instantly in front of an audience or the customer) is because it guarantees a good initial result. If the light is way off or moving around because of wear the timing will not be correct.

If you want to see the SUN distributor machine in action you can go to junktube or watch the movie Pit Stop (also on junktube) where they show it being run. I love that machine. You can set up those dual point systems perfectly. You get the lights for the fixed set lined up and then move the other set until all the lights are lined up. I only knew one place that had it.

I forgot to mention it is on a '41 120 sedan.

Thanks

Hi,

I forgot to note that it's a '41 120.

Thanks

Good. I thought i was losing what's left of my mind.