Lets look at the different options out there :
2F stock
250 duration
Int 17-53
ex 55-15
lift ?
3F stock : ( and Melling MC803 ) Jim40's choice
250
INt 22-48
EX 60-10
lift ?
Isky Z99+E3 grind
258
INT 21-57
ex 57-21
lift 425
Isky z99-005 grind
260
Int 25-55
ex 55-25
lift 406
In another thread the following Delta grind gets mentioned: ( this is so close to stock 2F - I do not see the sense )
Perf 250 S grind
Duration intake 250
Duration exhaust 254
Intakes opens 17, closes 58
Exhaust opens 60 closes 14
cam rise .255 L/C 108 degrees
Lash intake .014 exhaust .014
KC 859 - MarkW's choice
262
INt 24-59
ex 62-34
lift 440 (?)
I am trying to make sense of these figures . ( the following info taken from other threads )
Lower duration cams produce the power in the lower RPM range. Larger duration cams operate at higher RPM, but you will lose bottom end power to gain top end power as the duration is increased. (For each ten degree change in the duration at .050", the power band moves up or down in RPM range by approximately 500 RPM.)
Advancing the cam will shift the basic RPM range downward.
Too little compression ratio (or too much duration) will cause the cylinder pressure to drop. This will lower the power output of the engine.
So to apply to my situation :
I am raising compression and overbore ( 8.8-9 :1 ) = more power
If I fit the longer duration KC 262 cam , it may counter the higher compression but will also move the powerband up by 500rpm . The same KC grind is advanced in timing and will move the powerband down = back to where I started
The Isky 258 grind is similar in timing than the 3F but longer duration . So the engine will be very much the same but rev more comfortably at above 2000rpm (?)
Help me make sense of this