90 firebird formula,stock motor except for intake,cat and flowmaster crossflow.not sure if its a roller motor or not.but whats the largest cam I can run in it with out changing the springs/heads?

 

If its the original motor then yes its a roller motor. I really suggest if you plan on doing a cam you get a cam/lifter/spring set, and change the timing chain. I spent about $220 for a cam/lifter/spring kit and double roller timing chain. I went with a summit (crane) cam 204/214 @.50, 420/442 lift. Its really good for low end torque which is a good match for TPI and its still compatible with the computer because of the 112 degree LSA. I believe your running speed density so a tune is a must otherwise you wont notice to much at all. But back to the point you could go a little bigger than what I'm running but deffinatly change the springs.

 

i cant find a cam for less then $260 and the cam i was gonna go with was crane energizer .447 lift

 

Your 1990 has a roller cam, and you'll want to keep it for all the benefits such as more power, lower emissions, and better gas mileage.

The largest cam would be the Crane Compucam 2032. However since your stock springs are almost 20 years old it would be a very good idea to change them too. And change the valve stem seals too so you dont get the puff of smoke on startup. I can recommend the Manley 22410-16 springs and 23652-16 retainers. That'll let you run up to .525" lift on stock heads. Then you could use the ZZ4 camshaft, which is a little cheaper and easier to find. The stock computer should be able to handle either one of these cams, especially the ZZ4. Any engine will benefit from a custom chip tune.

However, changing the camshaft is a HUGE project, and not recommended unless you're also changing the timing chain as said above, as well as the intake manifold. Why put the stock intake back on when you can put an aftermarket one in that flows better? In the end this ends up being a huge cost project and is why I dont recommend a cam swap for a stock engine.