Advancing Cam Timing

[Joe Prochazka]

I am advancing the cam timing on my 390 to pick up a little more bottom end. I have pulled the water pump, pulleys, timing cover, chain and cam/crank sprockets.
All has gone well as I have reinstalled the crank sprocket with the "A" tooth aligned with the cam timing mark (6 0'clock position).
I getting ready to seal everything back up..........
What bothers me is...........this is an Edelbrock timing set and on the crank sprocket, besides having the "A" and the "R" on the teeth......it also has "2 deg" stamped on the sprocket.
Would this mean that this sprocket will only advance 2 degrees and not 4 degrees as advertised?
It seems wierd that Edelbrock would make a 3 keyway crank sprocket and then only give you a 2 degree movement.
Has anyone seen this on their Edelbrock timing set?
Thanks in advance.

[Rick Parker]

The 4 degrees you speak of may is probably the total swing available IE: from 2 degrees retarded to 2 degrees advanced. 1 position is 2 degrees retarded, 1 is "0" or "straight up" and lastly 2 degrees retarded.

Rick

[Joe Prochazka]

Summit catalog says normal, 4 degrees advance, 4 degrees retard. Edelbrock website says multiple keyways........no other details.

[HighPlainsDrifter]

Joe,
The crank has to turn 2 times for 1 cam revolution, so 2 degrees at the crank are 4 degrees of cam timing.
Perry.

[Joe Prochazka]

Perry,
That sounds reasonable........so it sounds like I'll be safe to go ahead and put everything back together and see if the car picks up some bottom end. Maybe I can be back on the road tomorrow.
Thanks
Joe