Date registered: Aug 2008
Vehicle: 1971 250C
Location: Toronto, Canada
Mentioned: 0 Post(s)
Quoted: 14 Post(s)
With a great help from this forum I think I am getting closer to fixing the engine "noise" on my 250C W114, dual zenith, M130 engine.
Little bit of background before I ask my questions:
The car had spark plugs, cables, oil replaced and came with upgraded crane igntion and original coil.
Valves were adjusted to 0.003 and 0.007.
The car starts fine, idles fine and has power.
Oil pressure sits at 10 on idle and increases as the engine rpm increase, nothing unusual there.
The "only" problem I have is "noise" coming from the engine under load, specifically accelerating from 80 to 100km/h.
I called this noise knocking, pinging, flapping, metalic clicks at least multiple times so I don't know if I am describing the noise properly.
I think the best description that I found was a metal can full of marbles shaken violently. That's how it sounds.
One mechanic decided it is the crankshaft bearings causing the noise.
Another engine rebuilder suggested opening the engine as a last resort and suspects it is the timing.
on the timing.
Since my three way vacuum valve needed for US emission doesn't work I am bypassing it.
My vacuum lines are as this:
Second carb (closer to the firewall) has the lower vacuum going to the dashpot.
For the first carb (which has excellent vacuum) I have tried three options:
1. plugged (this setup gives the best results with almost no pinging or at least less)
2. going to the advanced plug of the distributor it almost stalls and it pings
3. going to the retarted plug of the distributor, pining is very pronounced.
I have had my timing set to 3 btdc, 8 btdc and 13 btdc as some suggested and the best results I got are at 0 with the first carb plugged.
All of this leads me to the distributor or ignition setup.
I don't know how to confirm the distributor is working but I can guess it is not coping with the rpm changes.
Then I realized at one time I touched the little vacuum on the side of the distributor but I can't confirm what are the correct settings.
Picture attached of the side vacuum (not mine but the same) and I can see that this will have an effect of the distributor.
My question is how can I adjust this vacuum diaphragm to make sure it is working fine and how can I check if the distributor is working fine before I get to the ignition portion?