Are there any differences between 862 and 706 heads besides the notch? Do 706s flow slightly better? why did GM change the casting # if there the same head? Which heads would you buy?

If I buy 862 heads and they have the notch, how much milling is needed to remove the notch? If I can be removed!

I run 87 octane with all boltons dyno tuned

If no notch I plan on milling the heads .01 and getting .04 cosmetic gaskets

COMPRESSION
stock 9.5

.01 milled 9.7

.04 cosmetic 9.96

.035 cosmetic 10.05

I know more compression and low grade 87 will mean timing will have to be reduced. So how would 9.7 compression run with 87 tune? If I go with cosmetic gaskets I will run 93 octane tune even know I dont want to add another $5-10 on top of $70-80 it cost to fill up now.

What would yall do?

 

Not all 862's have the notch.

 

I have read that late 2000 through 2002 didn't have the notch

I believe they switched to 706s in 2002 < not 100% on the history

 

706's were out from the beginning. Not all the 706 castings are bad. 706's were used all the way up till 2007 Classic. I bought an 4.8 with 706 heads that came from an 07 Classic.

The heads were cast using a different casting process. The 706 has a more consistent casting with less core shift. Once you start porting them there really no different.

If your looking to have work done, I would get a set from one of our sponsors. Both SDPC and WCCH have ported 5.3L heads starting at $899.

Hell the last set of heads I had redone cost me $300 in machine work and I supplied all the parts. If you price in the parts these guys use, Like new valves, springs, and seals, the porting is so cheap why not spend the money...

 

Got a set of 862s with no notch last night for $80 with 55K on them

I'm a broke college kid that's why I can afford to get them professionally cnc

I plan on taking out the rocker lumps and blending with 140 grit. Take a lil of the exhaust side but not much

What do yall pay for milling? I dont have money for a valve job so I'm going to just lap them. They already come 3 angle from factory.