220Sb Ignition Settings and distributor advance stuck
 

Hello,

Post Carb Rebuild, was going thru the ignition settings again before attempting to tune the carbs.

Plug Gap ~ .8mm
Rechecked Valve Clearance
Set the point gap at .33mm
Dwell 32 - 34 degrees @ 960 rpm (I have my idle set a little high right now)
Timing was 6* BTDC @ 960

The books say 2* BTDC. Is that where you other Fin owners are setting ignition timing?

Did a quick check to see if the vacuum advance worked, and it did.
PROBLEM: The timing did not return to 6* after releasing the throttle. It was up around 20* at 960RPM.
I could smell a different character to the exhaust, and I could hear a subtle burbling miss.
The spring plates are located under the points? Anything else I could do besides cleaning and lubing?

Thanks for the help.

I'd pull and clean / lube the entire distributor.

This is probably a "standard" Bosch distributor so pics / vids of most any Euro German centric car ( like VW / SAAB / VOLVO ) would be similar.

The plate where the points attach is for vacuum advance, the distributor rotor shaft leads to the mechanical advance.

You can check for the vacuum advance sticking by pulling the dist cap / rotor / plastic cover ( not all have this or it might be missing ) then applying vacuum to the canister and checking movement. Also be sure the ground wire is intact between the moving point plate and distributor housing. Old grease ends up insulating the two plates a bit and the loss of a ground wire can lead to a missfire.

When you remove the rotor, there will be a felt circle stuffed in the hollow of the shaft, this is an oil wick to keep just one part of the mechanical advance lubricated. You should be able to turn the rotor in one direction and have it spring back.

Generally there are 2 types of springs in the mechanical advance system, a small diameter wire with round eye ends and a larger diameter wire with one oval end / one round eye end. These springs make a 2 step advance where from zero to below idle RPM the timing is retarded to allow for easier starting then a flat spot in the advance curve to promote stable idle. If this flat spot was not there, a slight increase in idle speed would result in increased mech advance that would increase idle speed and result in more mech advance.

Thank you for the awesome reply. I'll work on it as my non-existent spare time allows and report back.

The mechanical advance didn't look too dirty and the parts seemed to move fairly well. The vacuum advance plate was kind of gunky and didn't slide smoothly.

At this point I don't think I'll dismantle the distributor any further, I don't want to mess something up.

I'm happy to report that the advance seems to be working now. After a cleaning and light oiling, the timing returns to "normal" after blipping the throttlw.

Now to set the timing and adjust the carbs. I may be able to declare this thing road worthy after a long hiatus.
I'll be watching the timing settings closely, I've been opposed to veering away from all original but after all this work to get it running right, if a Pertronix ignition can improve/maintain smooth running, it's an option on the table.