Vortec Head Casting #'s:|
I am using stock vortec heads, casting # 12557113. These are not the more popular/better known 772's, but they are from the same genre (1996 and newer heads from Vortec engines).
Vortec Head Fitment:
As most people know, there are a couple of ways to get these newer style vortec heads to work.
The problem is that the heads do not bolt up directly to the lower intake of the syclones/typhoons. In my opinion, there is a good way and a bad way to make it line up.
The bad way, or less desireable anyway, ends up lifting the lower intake up off of the heads using spacers (or two sets of gaskets: the stock syclone/typhoon gasket and the stock vortec gasket stacked together). I do not like this method, but it is the cheaper/easier solution.
The better way, or the way I chose, it to machine the lower intake to line up with the heads properly, and then drill/tap the heads so you can then bolt the intake to the heads.
Step 1: Clean the lower intake
I had my lower intake jet washed and glass beaded. As you can tell in the following pictures, it makes a HUGE difference. This process turned my 100,000 mile, never-been-cleaned, lower intake into a brand new looking piece. I was extremely happy with the results, especially since it only cost $35 at the machine shop.
Step 2: Weld Lower intake
After my lower intake was nice and clean, i had the machine shop add material to the edge of the intake runners. This is necessary to make the lower intake match up to the intake ports of the vortec heads. If you didn't do this, you would have a fairly large gap between the heads and intake, making the combination unusable.
Step 3: Drill and tap Vortec Heads
With the intake ready to bolt up to the vortec heads, the head must be drilled and tapped to match up with the bolt holes of the intake. Also, I opted to use Fel-pro gaskets rather than the stock plastic gaskets. The stock plastic gaskets are neat because they snap onto the heads. I personally don't like the design of these gaskets for our setup,
becuase to get the lower intake to bolt to the heads, you have to drill directly through the gasket at a point of its rubber seal, which I think is just asking to leak on you. This is why i prefer the regular flat Fel-Pro gasket.
Step 4: Ready to bolt on!
Everything has been done to make the heads and intake bolt up, so its time to assemble. Here are pictures of how my intake lines up pretty much perfectly with the heads. You can also get a better look of the nice welds the machine shop did for me.