I have a 1991 305 V8 automatic firebird what is the biggest cam swap that I can put in that motor without blowing it up I'm going for mad Max here trying to make the 305 as mean as I can get it need tips please and thank you

 

It all depends on your ability to DIY tune the EPROM. Veering from stock will require a new EPROM tune. Without it, you'll have a stumbling, gas eating mess. I would spend some time reading in the TBI/TPI (not sure which one you have) and star to arm yourself with info.

 

Welcome aboard Hopper.

Assuming you are set on running the 305....and assuming you want a fairly max effort engine, you can use the forum search tool for "334", which is a stroker 305. There are several good threads by a member or two who have built them, complete with dyno results. Lots of good reading on this forum.

 

Why do you want "the biggest" cam that you can put in that motor? Do you want it to run like crap and have no low-RPM power? Do you want to remove the ECM and install lower gears along with a higher stall-speed torque converter? Do you plan to spin it to 6500 or more RPM?
A sensible cam swap for that engine would be one with a higher lift than the stock cam, SLIGHTLY more duration, and a lobe separation angle that will produce enough vacuum for power brakes (basically a mild "RV" cam)...

 

I’m not going to say anything that hasn’t already been said but I hope that the more people that tell you this, the more you’ll see the wisdom in what you’re being told. Unless you’re willing to dive deep, bigger stall, steeper gears, high quality lifters, new pushrods and new valve springs, new double roller timing set, likely machine the heads for valve guide clearance and possibly more, the car will only sound cool at idle. Everything else about it will suffer. It will be slower. It will get worse mileage. It will have worse manners at low speeds and highway cruising unless you just want to stick it in drive and forget you have an overdrive transmission. Get too big with excessive overlap because of high duration and narrow separation angle, which is what gives it that nice chop, and you’ll need compression to retain any driveability. Those 305’s all came in under 9:1 which is LOW, if they still retain the factory .015” shim. Even lower if someone replaced it with an MLS gasket as happened with my old 305. If you do it right and address everything you need to get the big bad cam you desire simply to make a cool sound at idle, then you’ll still be stuck with a small displacement V8 and small heads that flow miserably with a factory induction that chokes off all power where your big nasty cam can make it and you’ll be slower in the end… all because you want it to sound nasty at idle. I said all this to simply tell you the only way to get a nasty sounding engine that you won’t hate to drive is to build a nasty engine and the driveline to handle it and that’s expensive.

 

Should we point him to the BIG ***** THUMPR ?

 

Based strictly on OP's posted requirements, that cam is exactly what the doctor ordered, and should work extremely well with the stock engine and ECM.