051 distributor vacuum-retard problems.

[tonyfern75]

trying to set the timing on my 67' 230 sl. First problem is the hex screw that tightens down the distributor is stripped so if anyone knows of a trick for getting the screw out without drilling out, I'd appreciate the response.
Also noticed that the vacuum hose has no affect on the unit. timing looks to be set at between 4-8 degrees btdc using my timing light. I'm gauging this in that the mark I see with the light is between 4-8 degrees to the left of the pointer (if you were looking at the damper from the front of the vehicle, not leaned over the side and staring down at it from the engine side-in which case the white mark would be to the right of the pointer, by all means correct me if I'm wrong here   From what I've read, I gather that this setting should be ok, if the vacuum retard were functional.
The problem I'm trying to solve is that the engine is running rich. Before going into the IP I'd  rather be sure my timing is right. 
I will check for vacuum on the hose with a gauge tomorrow. If I get a reading of more than 5-6 inches on that hose, then I'd assume something wrong with the vacuum retard can..right?   I've already checked the points gap and dwell and that seems to be right where it should be.
As far as I know the intake venturi flap is fully closed at idle and the engine is idles well at 800 rpms warm. brand new ngk bp6es plugs are carbon fouled.
my hope is to get the vacuum retard working right and maybe not have to turn the distributor for now as I can tell getting that hex screw loose may not be a walk in the park.

Any advice on either problem would be much appreciated.

Tony

1967 230 SL

[al_lieffring]

I thought that my throttle flap was adjusted correctly, but decided to throw it in the ultrasonic parts cleaner anyway. Once all the accumulated gunk was washed off, the adjustment screw was almost full turn off. after that the vacuum worked correctly.

[tonyfern75]

today managed to turn the hex screw on the distributor so I could finally adjust timing. Went for a little more initial advance (got the full 30 degrees at 3000 RPM's) but I noticed that if I turn the disty any more counterclockwise a part on it would get in the way of the hex nut adjustment so stopped there and backed off a little. Please advise if anyone thinks this would clearly be too much advance and I will gladly back it off some.  also backed the venturi screw at the air intake off a little more and was able to get 10 inches of vacuum on the gauge instead of 5 so the vacuum retard seems to be working better (notice some drop in RPM when I connect the hose. However, my 800 RPM at idle has dropped to between 600- 700 in park and goes even lower when I put it into drive.  This seems to be affecting driveability a bit.  I figured a little more advance might help me get better fuel burn and kick up my idle RPM to counteract what I lost by closing the venturi flap a bit more, but this is not what happened. Does the distributor hit a point where you get no more advance by turning it, because it certainly felt this way regarding RPMs (perhaps at this point I was getting detonation but could not hear it?  Should I have left the disty alone and gone straight to IP and throttle linkage adjustments?

Did turn the idle mixture screw on the back of the IP counterclockwise a few clicks to see if that would lean out the mixture a bit as this was the goal from the beginning. wondering if I should have left well enough alone and dealt with a slightly rich mixture, but would rather have everything exactly as it should be. Still  a bit running a bit rich and now have a less than optimum idle.

Any advice would be appreciated.

[Tom Colitt]

Hi Tony

It sounds like your main problem is a rich running engine which is the case on 2/3 of these cars as the barometric compensator vacuum box next to the thermostat stack in the injection pump wears. Try unscrewing it and removing one or two shims to lean out the entire rpm range and see if that makes a difference. Many experts eliminate the ignition retard altogether anyway and set up timing at a few deg. BTDC in any case....

Regards, Tom