VIPER RED Are the vortec heads you have factory castings or have they been reworked(valve guide clearance)? And what number casting are they? Is that a vortec air gap?

 

the heads are off a GM crate moter 330 horse ho thers aprrox 1000 miles on them the intake is never used vortec air gap the heads have never ben machined they came off a close freinds car he only drove for a month in a 85 montecarlo full inter it ran 13.1 107mph with a 600cfm holey and onewheel pel.on normaL STREET TIRESthen we pulled the heads and put a set pf pofted and polished ones that my dad had lying around insted of grinding on the new ones.l These heads with a roller cam on a 350 could get low 12s easy .

 

I like the vortec heads for a low cost build they are great the only problems with the stock ones is that you are limited in lift the stock vortec head will take anywhere from .450 to .460 in lift depending on the head. It is limited because of the valve guide height and the are limited to a single spring because of the guide diameter... its not a big deal to have them machined for clearance but just something to keep in mind. I cheated on the set I have and ground down the retainers for the necessary .060 inches of clearance beyond the cam lift., but I only ran a .470 lift cam. I reality though the unported vortec doesnt gain a whole lot with lifts beyond .500 anyhow. I am not real familiar with the Holley heads the dd dyno specs (if it is the correct holley head) puts them above the vortec not by alot mid range but at higher lift, I have to go back out today and I have some other computer stuff to do when I get back but I will try to research them more. Here is an artical I found that discusses them a little http://www.chevyhiperformance.com/te...est/index.html

 

Thats for the help guys. I decided to buy the lunati cam. I did not get the single plane manifold. hopefully the weather gets better so i can install everything