2004+ Vortec heads

[HotRodV6]

Ok, i just bought a set of Brand New 2004+ vortec heads from a fellow board member and i want to find out what all the changes are to these heads. I thought all the 98+ heads had 8mm rocker stud holes but these are bigger, maybe 10mm and i know they have a hardened exhasut seat, which i thought all heads from the mid 70's and up had those for unleaded gas, but are these different. Also on some of the rocker stud holes they are threaded all the way thru to the intake runner, so i guess they did that to elimnate that bump some of the older heads had so you can get more flow.

My plans are to put in Manley race flow 2.055/1.60 valves and comp 987 springs and matching retainers and locks, and i want to do some minor port work and will be running a 422 cam.

Thanks for the help and info.

 

[jwaller]

Re: 2004+ Vortec heads

if they are 04+ they most definatly should have 8mm studs and shaft mount rockers with alum tie bars. if they dont have that I seriously suspect they are not 04+'s. they do have have the stud bump.

 

[HotRodV6]

Re: 2004+ Vortec heads

if they are 04+ they most definatly should have 8mm studs and shaft mount rockers with alum tie bars. if they dont have that I seriously suspect they are not 04+'s. they do have have the stud bump.

Well i have a set of LS1 rocker studs that are 8mm on the bottom and 3/8 on top and they are to small to fit the rocker stud holes. And the holes go sratight thru to the intake ports, and there is no bump on the roof of the intake runner, i had a set of 99 vortecs before and they had the bump and 8mm rocker stud holes.

These are the same heads Mike@RPM is selling, the boeard member i bought them from bought them from Mike.


The casting number on them is 12557107

 

[HotRodV6]

Re: 2004+ Vortec heads

Well im not sure what all is different about these, maybe there are marine heads or something, but i bought the ARP 60 degree rocker stud kit that it 10mm on the bottom and 3/8 on top and they fit just fine and screwed all the way in.

Now its off to the machine shop to have all the machine work done for the bigger springs and bigger valves and i will have them flowed after all the work is done.

 

[jwaller]

Re: 2004+ Vortec heads

if you use the LS1 springs you wont need any machine work for th elarger springs/retainers.

 

[HotRodV6]

Re: 2004+ Vortec heads

if you use the LS1 springs you wont need any machine work for th elarger springs/retainers.

Yeah i know that, but i already sent back the LS1 springs i bought a went ahead and got the parts recommended for the V6, the 987 dual springs, and 740 steel retainers and the 611 super 7 degree locks.

I also got the 7940 pushrods and 3136 timing set, and will be running the 875 lifters and 422 cam and 1318-12 pro mag rockers.


Thanks for the heads up thought.