big valve heads?

[devildogadam]

i was looking around online for some new heads (don't need them just looking), and was wondering about the late model 6.2 heads that came with bigger valves. Is this just a rumor or do they really exist. I do know that i helped my dad put some 1991 6.2na vin F heads on his 1994 6.5 turbo vin F truck and that it was a night and day difference in not only power but also fuel economy. So my question is, if they do exist where can one find them? can you buy new heads with the bigger valves? if so where?:dunno:

 

[scottm]

The big valve heads were the 82-83 6.2 engines. From what I understand, they had too many cracking problems between the valve seats. All 6.2/6.5 head cracking issues are because of gm's possibly cheesiest move ever - not putting normal valve seats in the heads, and instead induction-hardening THE BARE CAST IRON. If course they crack! But new GEP heads and, I have heard, new aftermarket (Chinese) heads have different metallurgy that supposedly doesn't crack as bad. The P400 engines have hardened inserts, but are much more expensive.

Anyway, I am planning to put the big valves into new cheap heads myself. It will require re-cutting the seats, which may or may not take out the hardening. If so, putting proper seats in is not too expensive. In fact it was commonly done in the 80's when leaded gas was phased out.

Here are the big valves on ebay:

http://www.ebay.com/itm/GM-Chevrole...Parts_Accessories&hash=item2c4a876330&vxp=mtr