If its a true '97 Vortec motor (L31), its a great starting point for a build.
- Internal vs. external balance are based on the crankshaft installed. If its stock Vortec, it should use a stock SBC balancer, but will need a flywheel for a one piece rear main seal.
- Vortec iron heads seem to be prone to cracking, so make sure they have been checked before they are installed.
- Stock Vortec heads only support cams with limited lift (about .420) before the springs bind. The heads can be modified by grinding down the spring seats and providing more clearance, or you just have to choose the right cam. I think one manufacturer also sells a different set of springs that allow a little more lift.
- With dished pistons, I hope they kept compression to at least 9.5. You could use more, but 9.5 is very forgiving when you use cheap gas.
- Stock Vortec heads use pressed-in rocker arm studs. This works fine for most cams, but can be an issue with agressive cam profiles. Some folks pay to have the heads tapped for screw in studs. Probably not worth it for your application.
-The original L31 cam is about 191/196 @ .050 duration. For your truck I would just swap in an upgraded roller with about 214/218 duration, which would provide more power while keeping the low end torque. It will still idle well and be a very good street cam. Don't get carried away with rump-rump sounding cams that sound tough but are poorly matched to your truck.
I like the Howard's roller cams myself, but there are many other brands available.
- Use a good dual plane Vortec intake (Edelbrock, etc,), and at least a 650 CFM carburetor. Long tube headers and full duals are also best.
- You probably have a stock 700R4 with a fairly lame rear end ratio (3.08?). Swapping in a set of 3.73 axles would really wake the truck up, and with overdrive it would still be fine on the highway.
- If you go with a much more aggressive cam you may want a higher stall torque converter. However, I would leave that mod until much later, and its probably not even needed if you stick with a reasonable cam.
Bruce