Is my head gasket blown?

[Tyler S]

You may need a hotter plug to start with. However the only way to truly check your air/fuel mixture is to have it tested under load on a dyno or use a wideband O2 meter. Setting the idle CO screw only adjusts the af at "idle". The mid and high range screws really should be left alone unless you have access to a dyno. You may want to try adding/removing shims under the baro compensator or the WRD- Or adjusting the full range set screw if its easily accessible. Again, you need some way of measuring your af to get this right. The injection pump adjustments should be last on the list. Check everything else first. IE.. linkage adjustments, vacuum leaks, timing, dwell, etc.

[rgafitanu@gmail.com]

Tyler, which one would be a hotter plug? Hotter means it gives a stronger spark?

[Tyler S]

A hotter plug means it is less likely to foul out. The electrode is protected by the porcelain and is designed to retain some of the heat from combustion. Too hot a plug and the electrode can actually glowred hot and cause the air fuel mixture to "preignite" before your spark takes place. Too cold a plug and the fuel can saturate the electrode and cause it to foul. NGK BP5ES or BP6ES seem to work best. The BP5ES being the hotter of the 2. The Bosch plugs these cars came with are NLA. You most likely will gain an improvement either way as the Champion plugs your currently using have been known to cause issues.

[rgafitanu@gmail.com]

I put BP5ES a few hundred miles ago. I pulled 2 plugs today and they look like this. To me it looks very lean and it explains the rpm "chasing" at idle. What is interesting is that the linkage test tells me I'm in the sweet spot (engine sputters if I push either of the throttle or IP rods).
I gave the IP mixture screw 3 clicks towards rich.

[Tyler S]

The split linkage test at idle is only good for rpm up to about 1200 rpm.  all other rpm ranges above 1200 rpm are controled by the governor and part/full load springs. So sounds like you are good at idle but may have a lean condition under load or higher rpm cruise. These engines like to run better at idle a little on the rich side. So if 3 clicks rich cleares up the surge at idle then you should be ok. Just be sure your not going lean under load

[rgafitanu@gmail.com]

Forgot to add the pictures, they tell a lot.

[rgafitanu@gmail.com]

I actually think that it's lean at high rpm. There is very little response when I try to accelerate it uphill above 50 mph.

[Tyler S]

Those are the hotter plugs. The deposits on the electrode look ok. You may need a few more miles on them but I agree it looks lean. Is your total timing advance working correctly? 35-38 deg @ 3000 rpm and above.  Try shimming the baro compensator to enrichen the entire fuel delivery map. You can also back it out (unscrew counter-clockwise) slightly untill you have the adjustment exactly where you want it then use feeler gauges to determine what size shims to install. You will need to go back and adjust the Idle CO knob and air screw anytime you change the main rack adjustment. (Shim the baro, main rack adjustment screw, wrd shims)

[rgafitanu@gmail.com]

So to repeat what has been said many times. The correct way to differentially adjust mixture for rpm is by adjusting the IP black and white screws. However this can be done on the bench only. The practical solution is to make a uniform adjustment across the entire rpm range through the rack screw or the baro. But they need readjustments of the idle IP and air screws. Wouldn't the rack screw adjustment be more direct and easier than shimming the baro?

[Tyler S]

Yes I prefer adjusting the main rack adjustment screw. However its easy to get lost while doing this as you are working blind and question "was the screwdriver actually turning the screw". Some IP's with both start enrichment and fuel cut solenoids can be a pain to get to. A 14 mm head bolt/shaft just above and behind throttle lever needs to be backed out about 5-8mm in order to move the internal enrichment solenoid arm out of the way enough to gain access to the set screw. Best/easiest would be to see if enrichening via the baro shims first corrects the problem, if so then return the baro to original position and go after the main rack adjustment. What type of pump do you have? (R12, R18, R20, etc)

[Tyler S]

Also, if you find that you can correct the higher RPM problem adjusting the rack setting, there is a possibility that you will no longer be able to adjust the idle settings because the main rack adjustment puts the idle circuit too far out of range to adjust. The knob will bottom out before you are able to get it trimmed correctly. If this happens you will need to send it out to be rebuilt/adjusted on the flow bench.

I have had good success using a portable wideband O2 sensor setup for checking af alpha while driving the car. Gives you a lot of insight as to whats going on during different load/throttle inputs. And its a temporary setup. No mods to the car necessary. The sensor is clamped into the tailpipe. Just be sure you have no exhaust leaks as air drawn into the exhaust from a hole can skew the readings. Here is one link for the
Innovate LM-2. You may want to shop elsewhere for a better price.
http://ebay.com/itm/400935022778?

[rgafitanu@gmail.com]

I checked the timing yesterday. It was slightly under 30 @ 3000 rpm. I rotated the distributor to get it past 30 @ 3000 rpm but that changed the idle timing from 2 ATDC to approx 5 BTDC. The rpm increased at idle when I did that and it sounded better but if I am reading the BBB right it should be 2 ATDC. I have the 051 distributor with the Hot Spark thingie instead of points. Is there a way to correct the high rpm timing independent of idle timing? On the other hand if the engine sounded better and rpm increased, isn't that a good thing?

Radu

[Tyler S]

Your on the right track. Dont worry too much about the timing at idle. Set the timing at 35-38 degrees above 3000 rpm with everything connected. The engine will run its best with as much advance as you can give it without it pinging. Drive it hard after adjustments. You will then need to go back and adjust the idle CO knob and air screw to bring the idle speed back down. Being a 051 Distributer, it uses a vacuum retard. To check and make sure its working, remove the vacuum line over at the throttle body and you should see the timing advance about 5-8 degrees from your static idle timing reading.

[rgafitanu@gmail.com]

I drove it hard yesterday with the new timing. It is more powerful and idles better. I don't think I can bring the advance higher to 38, I have to be careful with the throttle because it knocks if I push it harder. I guess this is the result of the 3.27 diff swap with a 230 engine on a 500 lb heavier W111. I will try to shim the baro to see how it goes richer. Maybe that will make the knocking go away.

[Benz Dr.]

I would try that. This engine should easily run at 38 degrees full advance but it may ping if it's running to lean. At any rate, too lean is really bad for your engine and so is knocking. For the time being I would retard your ignition until it doesn't ping.

[rgafitanu@gmail.com]

So, I pulled the baro, it had 3.8 mm shims. I added another 0.3. The baro is the new model without the neck. It measured 21 mm so I assume it was working.. Took it on the highway, it does have more power however, there is still knocking if I push it too hard. I checked the split linkage @ 2000 rpm and idle and it seems to be on the spot. I raised the timing to 38 @ 3000 and ignore that the timing at idle is 8 BTDC and I guess I'm going to live with it?

[Tyler S]

8 deg at idle is no problem at all. Hopefully the coolant that was migrating through the crankshaft before the repair hasnt done damage to the lower half. You may want to back the timing off a bit. Make sure your gas is fresh and your using the highest octane fuel you can get. Looking back in the post I didnt see if you had the valves reworked. If so the added compression could be a factor in the engine knock. More stress is now being put on the bearings.

[rgafitanu@gmail.com]

It makes sense. I actually made a mistake and I forgot to put the shims, I found them on the table. That's why the mixture was good. So I did add 1 mm today and drive it after. It is more powerful but knocking is still present in the 1500-2500 rpm range, outside of that is OK. Now the split linkage shows me rich, I turned the timing down to to 33 and I will leave it there for the time being. I really don't want to open the IP to mess with the black screws. I hope that the coolant leak didn't mess anything down below, the oil pressure is against the peg all the time. I didn't do anything to the valves, you bring an interesting point about using 93 (highest) and I will do it. Funny, I filled up the tank with 20 gal. of regular right before reading your post.

Radu

[Tyler S]

Neat little quirk about the distributers. The top of the distributer/front timing cover has a 10mm set screw with a pointer and tick marks. This was used for making timing adjustments without a timing light, on the fly depending on what octane fuel was available in the area. Each tick is supposed to relate to 1 degree of advance. You could theoretically set this up now at the end of its travel, where it is running its best with the regular fuel, then advance it 5 degrees or so next time you fill up with 92 octane.   

[rgafitanu@gmail.com]

I always ignored that adjustment but I will use it. Do I have to loosen the Allen bolt or loosening the slotted/10mm vertical screw is sufficient?
I will fill up with the highest octane, I realize that these cars were made for good gasoline and this ethanol doesn't help.
Theoretically speaking, now that I isolated knocking to 1500-2500 rpm I can go two ways, adjust the black IP screws for richer or lighten the weights (or stiffen the springs) on the centrifugal of the distributor?

[Benz Dr.]

You can adjust the distributor flyweights but it would need to come apart to do it as it sounds like it may be advancing too quickly. I did this on my own car and it will run regular without pinging if I have to.

All old distributors need some sort of service eventually or your car will never run properly.

[rgafitanu@gmail.com]

I will have to see how it works with high octane first. I guess that the correct order for these adjustments would be:
- adjust mixture for correct CO over the range. If mixture needs to be adjusted across the rpm range, shim the baro or the rack screw. If mixture needs to be trimmed on a particular range, no choice but to adjust silver or black IP screws.
- adjust timing for 38 BTDC @ 3000 rpm. Check for timing and knocking at lower rpm ranges and adjust at the centrifugal weights/springs for smooth timing
- or get the 123 ignition and create your own custom timing curve to cover for the hard to do adjustment such as the IP internal screws or the distributor weights. Too bad their instructions make no sense.
Dan would you replace the springs with stiffer or drill the counterweights to make them lighter.

[rgafitanu@gmail.com]

So I got a full tank of 93. I can accelerate it now without knocking. The timing is 4 BTDC at idle and 35 at 3000 rpm and I would leave it like that. I wasn't expecting that much of a difference, when I played with different octanes in my W211 I couldn't feel any difference, actually I had lower gas mileage with 93 than 87. Anyway technologies 40 years apart.
If I would want it better I would get the 123 ignition with Bluetooth control.

[rgafitanu@gmail.com]

To my despair I found some orange foam on the dipstick again. Compared to the first post in this thread there is no foam under the valve cover, the engine is not overheating and the coolant level didn't drop. I hope it's just some moisture from the last days. I drove it in torrential rain. I took the dipstick out to let the foam evaporate. Interesting I find the same foam in my daughter's W203 oil filler neck that is raised from the valve cover, again no coolant loss.
Too much humidity. Water in gasoline, ethanol?

[Tyler S]

Give it a good long half hour run and that will burn off. Could be residual from your previous issue. Consider another post repair oil change in 500 miles.