[khall]

Ted,

I second the idea of checking your total advance. We can actually handle a couple of extra degrees of advance here at altitude. I run my 393 at 36 deg total with alu heads - iron should be happy with 34 total. Perhaps you could consider a bit of port work on the iron heads before you invest in new aluminum heads. Also your Holley is probably a bit too big for the 351 at altitude. I reduced my 750cfm to a 650cfm and picked up a noticable increase in mid range (3000 to 5000 rpm) response. An hour on a local dyno with a skilled tuner would probably wake up your 351 and give you a good base line to start from. Give Walt Hane a call at EPS in Evergreen.