Quote:It's only dangerous if the ignition pre-detonates ("ping" or spark knock). If you advance the timing too far, the engine will knock under certain loads. Yes, this is not good. Back off the timing just enough so it doesn't ping.

Set it at an idle (7 degrees or so) with the vacuum advance line to the distributor disconnected and plugged.

If you have the vacuum advance connected to the appropriate "ported" carburetor connection, it will stay at the same degrees at idle when you connect it back up.

If you have the vacuum advance connected directly to the intake manifold vacuum, the reading will be very different at idle (it will be advanced more than the 7 degrees). This is OK, just make sure to set initial timing w/o vacuum connected.

As Tsillay says, the vacuum advance can be removed if you are running a race car amd high RPMs. Locking the plates together lets your points rev higher without the slop. For a street car though, vacuum advance is good for performance. Or, fit an electronic distributor and you can keep the vacuum advance and not have the high RPM points problem.

Yeah, bang on the money Gary.
Total advance is the key, and in my experience an A series race engine wont take much more than 32 degrees at the peak torque RPM. (13:1 compression, Avgas)
A stock dizzy has too much advance in it, so if you set max advance to be 32 degrees, it'll only be 6 or so at idle and will run like a dog down low. You need to shorten up the slots in the driven plate to limit the advance, and while you're at it use weaker springs... Basically you can give it full advance by about 2000 rpm (A race engine will never be used under this RPM anyway).
You'll also need to get rid of the vacuum advance and lock the base plates together to get rid of the slop.

The best way to set this up is to get a knock sensor setup that lets you listen thru a headset, and start clocking up dyno time!

Pete O'leary still has a working dizzygraf machine if anyone's interested...

On the subject of ignition timing there are a couple of things to keep in mind.

I think the big thing is what the total advance is. Checking the timing at idle is more of a reference point than an absolute. If I remember correctly the distrubutor reaches full advance around 2500 rpm, maybe a little higher. Full advance is usually in the 32 to 34 degree range.

I have always used the timing light to get in the ball park but did the final fine timing adjustments by ear. Basically did full power runs up a steep hill by my house. Advance the timing a small amount at a time untill you start to get some pinging. back off the timing enough to stop the pinging and call it set! After this procedure measure the timing at the specified idle speed and note what the setting is.

If you get pinging at low rpm only the springs in the distributor may have weakened and are allowing the mechanical advance to kick in too soon.

Hope this helps

Gary

mate i took my ute with weber 32 36 to get fixed today and the guy had to unblock the emulsion tube and the venturies were heaps loose, he played with the timing but left it at 20 degrees he said its better to have it more advanced only if the engine doesnt ping which mine didnt. it runs very well now.

no were not talking about the carb. were talking about the ignition timing. The a12 has a helpfull set of cast numbers on the block beside the belt running from the crank to the alternator. put a strobe light on it (the belt next to the numbers) and it will tell you the timing in degrees. to adjust it loosen off the distributer and at the bottom there is another set of numbers +5 to -5 (i think) and you can move it which ever way you need to get the right timing. 7 degrees is the best for a a12. NO need to go more unless youve done something major to the motor. if you move the dist. while the motors running youll hear the difference in the timing.

69coupe ignition timing is the toppic
kegs yes we are

are u guys talking about automatic advance timing? i decided to check mine today and at idle it was advanced by 20 degrees my dad adjusted it and now its running sick

OK hang on a second.

I'm new to all this...

When you say degrees, you're talking about how many full rotations the screw on the carbi has been turned anticlockwise..right?

my book said 7deg at 600rpm
BUT I have run up to 19deg on my racer on avgas done 3 seasons like that still havent move it now.MITE start it this weekend see if it goes still.Bin a long while now