062 vs 906 Vortec Heads

[CORE402]

Hey guys. I had another thread up the other day and a little bit of an argument insued over 062 and 906 castings of vortec heads. I was wondering what the differences are and if one was better then the other. Any info would be nice. Thanks.

[68chevelle]

well i dont remember all the differences anymore but this will sum it up...
906------BAD
062------GOOD

ill try to see if i cant find some old articles about it.

k, i found the info. "For you junkyard hunters, be forewarned that some ¾- and 1-ton trucks came with Vortec heads equipped with a specially hardened exhaust seat that kills low- and mid-lift flow. Casting number 10239906 should be avoided."
got it off CHP's web sight. hers the link if you would like to read it for yourself. http://www.chevyhiperformance.com/ho...458/index.html
its at the bottem of the seconds paragraph.

[CORE402]

Hey man thanks a ton!!

[89IROC&RS]

do a search on threads in this forum, this has been explained many times.

the shorthand, is that the 906 castings were used on box trucks and work trucks, that would be under lots of high heat and load, so the exhaust ports use pressed in iron seats, that cannot be enlarged. unmodded the two heads are almost identical, but its this limitation for modification that makes the 906 heads less appealing.

the 062's can be ported polished, set up for 2.02 and 1.60 valves, and angle milled down to 54cc's. they flow better on the exhaust side, better scavanging the cylenders, therefore you want the 062 castings. you can get them off 96-99 tahoes, suburbans, silverados, and the GMC equivilents with 350 engines.