Just wondering what the difference is in the Vortec Castings. One is '906' casting and one is '062' casting. Is there even a difference? As far as i can tell both are 64cc heads.

 

i believe the 062 casting is the one that is cast in mexico and is the current casting. as far as performance goes, there is no differance.

 

One is from heavy duty trucks (906 ?), and the other (062) is from light duty trucks. The difference is in the valve seats.

From what I have read, but not seen directly, the HD truck version uses a thicker seat on the exhaust and so in stock un-ported form does not flow as well as the 062 version. IIRC it can be corrected, to do as well as the 062, by the appropriate porting methods. That's the only difference that I am aware of, and performance-wise they are the same IF the lip is removed on the seat(s) of the 906 head. Many people suggest avoiding them because they take more work to get them flowing on-par with the 062s. HTH.

EDIT:
http://forums.s-series.org/viewtopic...966&highlight=

http://www.chevyhiperformance.com/ho...458/index.html

There are also many threads here on TGO discussing the differences.... but I haven't searched thru them to find anyone with specific firsthand knowledge.

 

I've heard stories about the exhaust seat or whatever, may be true but it definately is not going to hurt the performance of the head. I *think* (could be very wrong...) 906 vortecs came off factory trucks and 062 vortecs are ove-the-counter replacements for them?

The flow difference is so minimal that you'd never ever ever notice the difference. My heads are 906's, my friend's 11 sec motor runs 906's, and they're both unported and run pretty darn good...