255 Mercury Timing

[TomO]

More advance does not necessary relate to more power. The advance should be set to factory specs for optimum power. The max advance for your distributor is 8.5 degrees at 2000 RPM. At idle speed, with the vacuum advance connected, you should have 2-3 degrees of advance.

 

[ford1]

im not going to argue with you over the correctness of the timing marks on the cam cover or the crank pully, but those were made by the thousands by machine that wear and change the specs and location on those parts, the pully notch only has to be off a 1/16" to drasticaly change the timing, it can and has even happened on the notch cut in the crank snout, all im saying is dont trust those marks till you are satisfied that they are true

 

[50 merc]

I did check for TDC with the #1 plug removed and the marks were right on the money so i just advanced it 2 degrese. So all is good so far

 

[V8 Bob]

"More advance does not necessary relate to more power. The advance should be set to factory specs for optimum power. The max advance for your distributor is 8.5 degrees at 2000 RPM".

TomO,
That's distributor advance and rpm, which is 1/2 crank values, or 17 degrees @ 4000 engine rpm. Add the 2 factory and another 2 at the crank and you have 21 total. Those specs vary from about 7 to 12 distributor degrees depending on whether it's a Ford, Merc, truck and year. But setting max timing to 20-22 is a safe starting point for most all stock flathead V8s.
Having the maximum amout of advance without pinging or detonation will give the best performance and economy with lower engine temps, something important on a flathead;



"all im saying is dont trust those marks till you are satisfied that they are true"

And Ford1, that's why I said to check the marks with an adjustable light, to be sure, on any engine.