Running Hot, Pinging and Dieseling
 

First I'll give the car info then I'll get into my problems

1970 280SEL 6cyl.
Rebuilt engine - has about 200 mi on it. New spark plugs Bosch W7DC. New water pump, new thermostat, new fan clutch, re-cored radiator, new MBZ coolant 50/50 with distilled water. Running a Pertronix unit retaining transistor switching and stock coil.

Runs hot ALWAYS. Temp gauge is at the first line past 175 I'm assuming its somewhere around 210F. It gets hotter if I let the car sit and idle - cools down a little bit at speed but not much. Also runs cooler with the heater turned on.

It is currently timed at 8 BTDC at ~800rpm with the vacuum retard connected. It's running on fresh premium fuel from Costco.

I haven't burped the cooling system, but it doesn’t seem like bubbles have been a problem with these 6cyls. At this point I am leaning toward a fuel/ignition issue. It doesn't seem as though raw fuel is pouring out the exhaust pipe, so it is conceivable that the car is running lean.

It stumbles for a few seconds on start up, don't know if it is connected with the above problems or not.

First 120 miles I had W9DC plugs in it (hotter) so I attributed the dieseling to those. I also had old fuel in it at that point and figured that was causing the pinging. Put 2 bottles of octane booster into 1/2 a tank of gas and it seemed to help the dieseling - didn't really do much for the pinging. Since then I have changed the plugs to W7's and filled up with a fresh tank of gas

Any ideas as to what is going on? Where/how should I be timing it?
Thanks for any help!

-Eric

Pinging is probably caused by your timing. The timing should be 4 degrees ATDC not BTDC with the retard connected.

Timing will also cause it to run hot.

Check your manual, there may be a listing for max advance at a specific RPM. Something like 38 degrees at 3800 RPM (example only, not real numbers!).

Setting it this way gets you around whether or not the vacuum hose needs disconnecting and poor idle issues.

Michael

oops - ATDC
 

Its actually set at 8 ATDC - sometimes I get my letters confused :dizzy2:

The timing is up to spec - w/
8 ATDC @~800
0 at 1500 (manual calls for 0-5)
and its actually over advanced at somewhere around 38? BTDC @3000 I believe the manual calls for about 32 @3000

I'm not having any issues (right now...) at higher rpms just at low revs

Thanks
-Eric

Give the rebuilt engine about 2,000 miles to loosen up and the temp should drop a bit. Get the advance set to factory specs as suggested and that will help cure the temp and pinging. Try setting the timing to about 30 degrees @ 3,000 rpm, or 37 degrees @ 4,500 rpm, w/o vacuum. Install a coolant recovery system to help purge the air and don't forget to use a sealed pressure cap. If at the end of the day if it still likes to run hot, use a good oil, like M1 15w50 (not EP) that can stand high temps.

230/8