Originally Posted by brenx
14 initial with premium (95) or 98 octane. with the cast irons. Cam's got 248@50. It's not what I call a massive or big cam. Still sorting issues to make it faster. Probably will always be sorting something. It's the nature of the beast (cars). With the alloys heads the ball game changed. I can now run 91 octane if need be but I still prefer not to.
Anything with around 230@50 upwards should be able to cope with 12-14 initial and 32->38 total running cast iron heads.
For Jocks' benefit I am running AFD alloys with 11.4 : 1 compression and my dizzy has 20 deg mechanical advance only (no vacuum). Cam is 248 @ 50 and 605 lift and I only run 98 fuel
I can set it at up to 20 deg initial on the balancer - in fact the higher it is the happier it idles and it still pulls without pinging with 40 deg total,
any more than 30 deg total and the power falls away.
So I have to set initial at 10 plus 20 in the dizzy = 30 total to make max power
Therefore, what brenx says doesn't hold true for my engine probably due to the high comp.
Ideally, I would like to have 20 initial and 30 total so dizzy needs to be regraphed with 10 deg mech adv