Ignition timing help

[col320ce]

I feel a bit stupid but I'm struggling with the setting the timing.
I have a 230sl 1964 with the IFUR 6   0 231 116 051 distributor. I have the early type single timing scale. 95 octane petrol. Dwell set at 37.
If I adjust it to 2 deg AFTER TDC (to the left of TDC when standing infront of the engine) I can't get the rpm on idle above about 550 - the idle AIR screw does nothing. When I move the timing to TDC the engine sounds better and I can adjust the rpms with the idle AIR screw.
Above is done with the vacuum connected.

On the timing scale the BTDC scale stops at 4. There is a lone mark somewhere else on the crankshaft pully without a number and there is another mark with 60.

I have a CO meter but I'm struggling to get it below 7 and turning the injector idle anticlockwise doesn't seem to be affecting the reading much... I feel I'll have to turn it 15 or 20 times to get it to 4 and I'm hesitant to do this without some help.

So...  Am I setting the timing correctly?
How do I set it to 12-19 and 30 deg if there is no mark on the pully?
Any advice on how I'm going with the tuning?

I've attached the technical data page I'm using...

Thanks for any help!

[ja17]

First of all make sure your engine linkages are set correctly. This is critical to all your other mixture and timing adjustments. Set the timing at 30 to 35 degrees BTDC at 3000 rpms. (idle timing is less critical). If you still have running issues with mixture and adjustments, determine if the engine is running rich or lean. Make sure you are looking at the BTDC side of the scale not ATDC. This is the half of the scale on the drivers side of "0".  It sounds like you are looking at the scale on the passenger side of "0".  Get back with us on what you find.

[col320ce]

Hi Joe
Linkages are done already.
How do I know what 30-35 degrees is? I can't see this on the scale. (Vacuum hose would be disconnected for this one - right?)
I've attached a picture to confirm BEFORE and AFTER TDC.
The scale runs out at 4 degrees BTDC - so where do I read off 30 degrees?  As I go around the pulley there is a line without a number then there is a 60 but that is on the ATDC side.
Thanks for you help ...

[Tyler S]

Col, each number is a division of 10. So if you see "3" on the crankshaft, that is 30 degrees.
Halfway between 3 and 4 is 35 degrees.
Leave vacuum line connected when setting total timing advance above 3000 RPM. Dont even worry about the timing at idle. Let it ride where it wants after setting. Then set your desired idle speed and CO.

[Benz Dr.]

35 degrees really isn't enough advance. I like 38 to 40 degrees for top performance.

The 051 distributor has 20 degrees mechanical and 10 degrees vacuum if it's working properly. This will give you 30 degrees of total distributor advance. If everything is working right, you should be able to set your timing to 38 degrees BTDC at 3,000 RPM and it will idle at 8 degrees BTDC at 800 RPM. This is with your vacuum line connected.

[col320ce]

Thanks so much...  it's all making sense now. Took the car for its first test drive since the cylinder head rebuild today and it's not too bad. A little hard to start and pinging a little under hard acceleration.  Going well enough to get it to the mechanic for a tune up and road worthy.

[Tyler S]

Make sure to use the highest octane fuel available in your area. If it still pings you may want to retard the timing slightly.

[ja17]

Yes, 38 to 40 degrees is great if your engine and fuel octane will permit. Use highest octane available, since these cars were originally designed for very high octane. Retard the timing if any pinging occurs.

[col320ce]

Excellent...  It has 95 it it now but will get 98 next time.

[col320ce]

After a trip to the mechanic...Running like a champ. Starting effortlessly and definitely prefers 98.