Hi everyone i have a stock 1986 iroc z 305 tbi. 5 speed. the engine and exhaust is completely stock, i tried smogging it and it couldnt pass so i just gave up on it. This is my everyday driver and im starting college this fall so i need a good dependable motor with okay gas mileage i need your opinions and scepticism, Im changing an all stock quadrajet to Edlelbrock 600 carb,a high rise holley contender intake manifold, new msd distributer, and mid lenght headers to straght pipes to dual thrush welded mufflers and removing all smog stuff. So how much of a hp boost will I get and will the gas mileage be affected substantially? I'm getting all these parts from my brothers 1976 camaro. He's upgrading his motor and getting new stuff. Thanks.

 

Conflicting information. Is it TBI or is it Qjet?
The only thing I see in your post that would be a good idea is the exhaust mods.

 

This looks like a serious contenda for the WORST PLAN EVAH.

Starting with

I fail to to how this

could POSSIBLY be the answer.

Since your motivation for doing all this is


it is not immediately obvious how glomming a bunch of random inappropriate used hot-rod crap on it is going to improve any of the above, LET ALONE get it through whatever smog inspection you have wherever you are.

Since you asked for

and I've given you plenty of the latter, now I'll give you my opinion...

Fix your stock carb and leave the motor alone, as-is. Rebuild your stock carb. Repair whatever else is broken about the car. Leave the stock exhaust system on it; repair it, or replace it with a good-quality boxed set cat-back, but DO NOT put on

as this hack job will not improve gas mileage, reliability, or anything else.

Yes I know. Yes I sound like your dad. Yes I have little kids of my own who already got the same talk.