I have an '83 F250 4x4 with a 460. It has 108,000 miles on the original engine. It has 4.10 gears, a C6 automatic and the compression ratio for that vintage was pretty low, I'm not sure exactly what it is. The engine burns no discernable oil.
In December 2005 I replaced the timing set and the water pump... the timing gear I used was spec'd for a 1970 Lincoln 460, and is thus "straight up," versus the 8deg retarded original timing set. Because of this, I had to adjust the ignition timing, since after the timing set install, the ignition was advanced 8deg over its pre-install setting.
Anyway, here are my findings (all numbers are BTDC):
30 - Hard to start, pings a lot even with premium fuel
25 - Not as hard to start, not as much pinging, almost liveable, good power & mpg
15 - No hard starting, no pinging on premium, excellent power, best mpg (almost 11 mpg!
)
6 - Easy starting, no pinging with any gas, gutless, 2mpg less than 15BTDC
I keep it at 15BTDC now, all the time. Even on regular fuel, it very seldom pings.
It's amazing how ignition timing can affect an engine. Set at the stock 6BTDC it feels like it needs an engine rebuild, compared to 15BTDC.
In December 2005 I replaced the timing set and the water pump... the timing gear I used was spec'd for a 1970 Lincoln 460, and is thus "straight up," versus the 8deg retarded original timing set. Because of this, I had to adjust the ignition timing, since after the timing set install, the ignition was advanced 8deg over its pre-install setting.
Anyway, here are my findings (all numbers are BTDC):
30 - Hard to start, pings a lot even with premium fuel
25 - Not as hard to start, not as much pinging, almost liveable, good power & mpg
15 - No hard starting, no pinging on premium, excellent power, best mpg (almost 11 mpg!
6 - Easy starting, no pinging with any gas, gutless, 2mpg less than 15BTDC
I keep it at 15BTDC now, all the time. Even on regular fuel, it very seldom pings.
It's amazing how ignition timing can affect an engine. Set at the stock 6BTDC it feels like it needs an engine rebuild, compared to 15BTDC.