I know I've changed my mind a million times on heads, but I found a set of 906 casting Vortecs from a 1996 350 locally. They've been decked, guides milled, screw in studs and guide plates installed, and assembled with Comp Cam springs, retainers, and locks. He wants $250 for them.

Now I already know the 906 castings have the hardened exhaust seats that supposedly kill low and mid lift flow. How much of a difference is there really?

My biggest concern is that the cam I bought is a Crane Blue Racer 1064. .488"/.510" lift/304 duration. I have 1.6 ratio roller rockers for the intake side, which puts the gross lift in the .520/.510 range. Will that cam outflow these heads? Can I make up for it with a little P&P (or a lot of P&P, I've got time, lol.)

I'm shooting for 350hp at the wheels. Are these heads capable of getting me there?

 

Only a million? The Vortecs are great flowing and performing heads right from the factory, and they can be made even better. When you say guides milled, were the spring pockets machined larger and the seal height lowered for more lift? Considering the work that's been done to them, at a price of $250, how can you not buy them? Just don't forget the issue of needing to buy a Vortec specific intake manifold. Whatever you have now isn't going to work.
Have you read these articles yet?
http://www.chevyhiperformance.com/ho...458/index.html
http://www.chevymania.com/tech/vortec.htm

 

I'm not 100%. The guy bought a Comp Cams complete kit with a .480" lift cam and had the heads professionally rebuilt with the new springs from the kit installed. I showed him that first article you have listed and he said everything required to run larger lift cams has been done.

I emailed Comp to see if the springs in that kit will work with my cam.

 

My machinist has a few sets of Vortec heads. I might buy a set from him. What casting number should I be looking for?

 

062's are the sought after castings. As I said in my original post, 906's have the pressed in hardened exhaust seats that supposedly restrict flow. From what I've read, the difference is little, and you can make up for it by blending the seat into the bowl better.

The pressed in seats were used in 3/4 and 1 ton trucks, so the exhaust valves would cool better under heavy loads. I personally see this as a plus...

 

In my opinion, you're better off with the 906's. The 062's can and have cracked the exhaust seat down the runner. The pressed in exhaust seats on the 906's was a fix for that problem. And since you plan on doing some massaging on the heads anyway, you can blend any step you may have between the seat and the runner. Go get 'em!!!

 

This is what I'm thinking. If I could get ahold of the guy again to see how much lift the guides and machine pockets were machined for, I would ****** them up!

 

Thanks guys!

 

Well I got them!! For $250 I feel like I got a pretty good deal. The heads seem nice, no major defects that I can find, deck surfaces seem nice and true, and overall they're very clean. Already have a coat of black paint on them, although that will get changed to Chevy Orange.

Still my biggest concern is that he is unsure of how much the guides were milled down, and if the spring pockets were made larger. I think what I'm going to do is install the cam, then install one head with an old head gasket and a pushrod length checker and see what kind of clearances I have.