Of timing and vacuum
 

A while back there was a thread about vacuum, how much you had and were it was measured. Or maybe it was on w116.org?

Anyhow, it got me to wondering why mine was so low at 13.5"Hg measured by pulling the climate control line at the firewall.

Since my mileage is kinda low and it goes poot for the first minute or so when cold and seems to be a bit sluggish, I decided to go old school when setting the timing.

Usually, I follow the sticker which in this case is TDC with vacuum lines connected. This time I used the vacuum gauge method which is to increase timing until you get around 17"Hg.

What a huge improvement!

My climate control would not bring the fan on very often as it needs to see vacuum from the temp switch on the servo, now it runs most of the time. The poot is gone. Better throttle response and it settles into gear nice and smooth. It also seems to have cured the run on, AKA dieseling.

Thing is though, the timing is now at 10BDTC and it pings lightly on WOT up a rather steep hill. I'm not too worried about that, I can always back off a bit.

Still waiting to see if mileage improves.

Michael

Finally had to fill up on the 12th.

Still runs great, mileage went up to 13.5MPG. Not bad for a short mixed drive commute.

Michael

< it pings lightly on WOT up a rather steep hill.>


Which means you are in pretty good time....
There are many car that don't run as well setting by spec b/c they are worn and don't have the compression , valve timing, etc. they once did...so there is absolutely nothing wrong with timing under load on the hill climb trick.
It is the engine talking to you instead of a book. And every engine is different, along with the petro the owner is accustomed to using........
Very Good........

The ping test is how I timed my '87 5.0 Mustang. Usually ended up around 14 advance and required premium fuel. Absolutely would not run on ARCO, even their top grade, I usually ran one of the top tier brands.

On the 450SEL, I figured the low vacuum was due to tired rubber under the hood but I guess not.

Michael