What I've got:
89 Firebird, 305 TPI, 700R4. Wimpy "peanut" cam.

What has been done to it:
3 inch mandrel bent cat back system. "Unrestricted" cat.
3.23 rear gears
Torsen posi unit.

Additional relevant info:
About six years, during a coolant flush, a thermostat housing bolt broke off in the manifold. It was helicoiled, but not helicoiled well...bolt ended up a little off center. Seeps a tiny bit of coolant from time to time. I'm afraid to touch that bolt again, for fear of making tiny seep into big leak.

The objective:
Get some more power from the motor. I'm not looking for a tremendous amount. This engine is not an ongoing project. This plan is probably the only modifications in this engines future. 350 swap talk is not helpful. There is a 350 (or larger) in this car's future...just not it's NEAR future. Replace lower manifold.

The plan:
The obvious place to look first is the garbage cam in this thing. I have a homeless ZZ4 cam at the moment. Using parts I already have on hand is always preferred, when it is possible, and does not compromise the quality of the job.
Replace lower intake manifold with aftermarket manifold. Possibly also runners to go with it.

The restrictions:
The zz4 cam has too much lift for the stock heads.
Heads are not to be pulled, and headers are not to be installed.

The actual questions:
How much lift can be run on the stock heads as they are (stock)?
How much can that be increased, without machine work (offset locks, and the like)?
If it cannot be increased enough to clear the ZZ4 cam, alternative cam recommendations are welcome.

 

get some retainer and locks along with springs and measure

make sure the exhaust has over .510

you may be able to do it

dont listen to anything but the measurement

and dont do anything without the measurement