GM847 valvetrain?
Originally Posted by TurboZ28
What all am I gonna need valvetrain wise to make a GM847 cam function nicely. Car is a stock 97 Z28 M6.
I would also like to know this as this is the setup I plan to go with in the near future.....
you WILL need to upgrade your Valve springs atleast. Something good to .600 lift will work. The 847 specs are on a 1.5 rocker. you could go up more with a 1.6 I got cranes double valve springs for mine.
A good Spring, like a crane 1.45" dual coil will do the trick but requires enlarging the seats and an ID spring locator pad, also ti-retainers and a good set of rockers wouldnt be a bad idea either
Lifters, Springs, Retainers, Pushrods basically a new entire valve train.... i used the k motion k-800 springs good to .600 lift from summit for like $80 bucks no machining work required. i also used comp cam 1.6 RR, lifters and there harden pushrods. also went with k motions retainers and valve locks everything is working out great.
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Verdad Gallardo Yeah I didnt think you had to replace the lifters...I was told 1994's came stock with hardened push rods? Is this true? If so I guess that is one less thing I need to buy along with the cam,springs, and rr's...
Originally Posted by z28boysteve
actually the stock lifters are pretty tuff and can take any cam you wanna throw at them almost.
Originally Posted by jninan2k2
Yeah I didnt think you had to replace the lifters...I was told 1994's came stock with hardened push rods?
I had 117K on my lifters so I went ahead and got some low millage lifters from my friends ls1.
TECH Resident
Joined: Jun 2002
Posts: 943
Likes: 2
From: Houston
stock lifters are perfectly fine, comp dual valve springs work great with the cam and the dampener reduces vibration nicely as welll. pushrods need to be hardened. Roller rockers can stay stock or upgrade, doesnt matter to be honest, just have to decide if its worth it to you. Should upgrade rocker studs to be safe. ARP has 1.89" long studs that work great and dont flex.
Originally Posted by Fade2blk500
I'd definitely upgrade the stock ones. The stock stamped steel rockers are weak and will flex and you'll lose lift because of it. 1.6 full roller rockers would do just fine 
Of course...I am in the process of ordering some crane gold 1.6 rr's...they should be here by the end of the week hopefully. I think the rockers will get here before tom
