Timing marks all over the place?
 

Hi, I'm trying to measure & correct the timing at idle. But when I use a timing light, I noticed that the timing mark moves a lot from left to right and back. What could be causing this? The timing light is new and I noticed the same thing when using another timing light.

I have the vacuum line disconnected

Is my distributor on it's way out?

Thanks

Hi elflamo mine did the same thing and it was because one of my plug wires was not on
Properly so it was not firing on all six cylinders.
This may not be your problem but worth looking at.
Thanks
Milke

I dont set my timing at idle, its best to set it at whatever advance you feel comfortable with at 4g.(depending on quality of fuel),,and then set the idle speed with adjuster screw. As far as it walking around on you at idle, could be bad dist (bushing ect) to a loose pully with a worn key way. Seen a few of those.

you can get a better "feel" with your ears than the timing light. Are you using a induction light? and yes check the wires, cap, rotor, plugs to make sure there all working like they should.

Make sure there is no arcing between/among wires. Are your points nice and clean? - I am not sure but if there are heavy deposits on the points when they break contact it may not repeat in the same manner.

There may be mechanical culprits such as:

Loose fitting cap
Worn distributor gear
Slop in the distributor shaft
Slop in the intermediate shaft (drives the distributor gear)

Thx for the replies.

Yes, using induction light. I will try to isolate the pickup so there's no chance of interference from other leads

The timing marks are supposed to be pretty steady in one place, correct?

Plugs, leads are new. Districap and rotor as well. I'm beginning to distrust the distributor. Will have it checked and refurbished if it stays like this

What CD box are you using? Is your ignition system stock?

Perhaps your earlier incident is causing problems...

I'm using the standard set-up (HKZ unit from Bosch, points, standard leads, standard coil). I think I'm going to replace the coil first and see where that gets me

How much is it jumping around, how many degrees deflection either way are we talking?

Whilst doing mine it may move around maybe 2-3 degrees either way at idle.

dist shaft wear might be a problem. worn points might cause it too.
but first i would pull the dist a clean it, i mean the corrosion. clean all the ground connections starting with the points and any place that is electrically related to the points/ground. also clean the outside of the dist. i put mine on the wire wheel on the bench grinder.
the shaft has to make good contact with the engine block. while you are in there you can check the mechanical advance and lube it if needed.

my timing would jump around and it got to the point that when setting the timing, when i moved or touched the dist, the engine would miss very badly, almost like it was going to cut off. this stopped all that.

Don't start changing parts until you investigate the spark scatter. The symptom you describe is indicative of a worn distributor bushing.

Remove the distributor. Disconnect the car's battery, using a wrench on the fan pulley nut, manually turn the engine until the distributor rotor is pointing at the radial line on the distributor body under the #1 spark plug. This is TDC #1 on the compression stroke. Without moving the crankshaft, loosen the distributor clamp nut with a short 13mm wrench and remove the distributor by pulling it up and to the left.

Now rotate the distributor shaft, does it wobble from side to side? Using a dial indicator, check the runout of the shaft, it's easy enough to fixture this up.

To me, the most likely cause is that the distributor shaft is wobbling around.

"Reassembly is the reverse of removal"

I have the same problem with timing on my '75, and I have been suspecting a worn distributor shaft bearing. Is there a way to replace the bearings on the distributor shaft and how much run-out is too much?

Just the cap, not the whole distributor. ;)

I found that timing inaccuracies caused by distributor slop were almost entirely rectified by replacing the points with Pertronix.

But Petronix isn't everybody`s cup of tea.

Regards, Mike Ruddy.

pull the whole dist. check for shaft play and clean it.

the points are grounded to the plate that moves. there is a braided wire that goes from the plate to the dist body. clean connection to the body. i think the plate side is soldered on. then clean the outside shaft that makes contact with the engine.

Thanks guys. I will move forward as you suggest.

movement side to side is mostly +-5 degrees but every now and then it's more like 30 degrees

Why isn't pertronix everyone's cup of tea by the way?

There are some detractors, there are reported failures and some folk just prefer to keep their cars stock..... 'You know where you are with points",

Pertronix is worth a try. Not too expensive and totally reversable... fit it and keep a good set of points in your glove compartment as insurance.

I fitted Pertronix 4 years ago and haven't regretted it.

"Quote DDK"

Addressing the shortcomings of the points next on my shopping list. I opted for Pertronix. Pertronix replaces the points and distributor capacitor completely with a small plastic ring containing 6 magnets that slips over the distributor shaft under the rotor arm. As the distributor rotates these magnets are read by a small box that is fastened down to the plate where the points used to live. With Pertronix there is no dwell angle to set and any play in the shaft becomes unimportant. (within reason)

http://i194.photobucket.com/albums/z...pertronix3.jpg

Well, having fiddled with the points quite a bit lately, I think I can do without that hassle and installed Pertronix asap. Thx!

When I check timing I clamp the pick up on the coil wire.

On the coil wire??? clamp goes on the no1 wire and power from one of the fuses on the left.

Try it you'll like it.
# 1 still fires and you can see the marks clearly. Done it for 30 years.