Baseline Linkage adjustments for 250se?

[Matt Strauss]

Hello.. I'm pretty new to this group. I have two W111 250se coupes, a 1966 manual and a 1967 sunroof manual.

My 1966 has what seems to be the classic warm start problem, and is also running quite rich.
I'd like to try and get everything correctly set-up. Are there baseline measurements specific to the 250se linkages somewhere here?
my initial search had turned up some general information, but nothing that specific yet.

[Naj ✝︎]

Follow the linkage tour in the tech manual.

I believe you need to be a full member to access it.

well worth becoming a full member 

naj

[ja17]

Hello Matt,

We can help you get your car running and starting well.  The engine linkage set-up is the critical first step. Next make sure the general engine tuning is good (spark plugs, points, compression). Make sure the fuel supply system is up to par (fuel pressure and volume).  Ask questions. The starting aid are a bit complicated but we can help you through that also.  Keep us up to date.

[Matt Strauss]

Nice article! It's exactly what I need and absolutely worth the price of admission alone!

I was able to make sure that the cold-start valve is operational and have replaced the thermostat inside the IP. I believe ignition timing is set correctly but I will double check it and put in new, fresh plugs to be sure before I get started. I How should I check fuel pressure?

[Matt Strauss]

I've gone through the process, and the car seems to be running really well now, and no more sticky sooty exhaust.  I think I might have isolated at least one problem.

The car starts cold perfectly every time. when I start hot, it just floods. - you can hear it start to catch for a split second before flooding the instant you turn the key.

after doing my linkage adjustments and warming up fully, I had the same flooding condition.

I disconnected one terminal on the injection starting solenoid and suddenly I had effortless starting when hot. of course, I have to crank longer when cold now.

I have had this solenoid off the car previously, and it seems to be free. therefore I wonder if the problem might be traced back to the relay which triggers it? is this connected to another sensor somewhere or does it always engage?

perhaps I'm only partway there and have discovered another problem that need fixing somewhere else?

[ja17]

Hello Matt,

Your engine will most likely have "Version Four" starting aids (1965-1970). The solenoid on the intake manifold should operate at engine starting temperatures below 95F. There is a second starting aid, which is the solenoid on the injection pump. It should actuate every time the starter is engaged. Use a 12 volt test light to check both solenoids during cold starts. Also review the tech manual section on the starting aids.

[wwheeler]

Hi Matt,

You have found the right place and made a wise move to become a full member. While not exactly the same, the W111 is similar mechanically to the W113 and this site has gobs of information.

I had a similar problem to yours in that if the cold start worked well, I had too much fuel for hot starts. I did the same thing as you and disconnected the IP starting solenoid when hot and would start perfectly. In turn, if the hot start worked perfectly, it took longer with the cold start. I actually have three starting situations: Hot meaning five minutes or less after shutting the engine off, warm 5 minutes to when the engine cools to around 100*F, and cold anything below that. Sometimes in a Texas summer, the engine never gets to "cold" . I went through all of the starting aids including the WRD also found on the injection pump. There are a myriad of adjustment possibilities and it is easy to lose track of what you did. So make good notes so you can go back if needed. 

Long story short (hard for me to do), I compromised so that when cold or warm starting I have to depress the accelerator pedal and it takes just a bit longer. Hot starts work great with no pedal. My reasoning is that less fuel delivery just takes longer to start where as a flooded condition will leave you stranded. I ended up removing the starting solenoid off to shorten the rod so that it doesn't engage the pump as much (less fuel). I did document by exactly how much so I can always go back.

I chalked this up to the pump and engine being 47 years old and there are many parts that have just worn. I am being a bit persnickety on this, so perhaps my condition is not as bad as it sounds.