Hi everyone i have a stock 1986 iroc z 305 . 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.

 

And the headers are ceramic coated as well

 

headers are fab'd to fit the body, not just the engine unless you want to do some cutting and fabrication

sometimes free really is worthless. Why do you want to remove the factory carb? What losses are you willing to accept by going to the edelbrock (did i really ask what losses are you willing to accept.....)


your question is a horse which has been dead for more than 20 years and has been beaten well (use the search under trying to make 305s perform)

open air element air cleaner, headers and free flowwing exhaust. Good luck trying to fit duals. It can be done but it's not worth it vs the dual out muffler

then, change your rear gears.

you will come to the same conclusion about the 305, it's just not cost effective to try and convert to performance. It has to do with the small bore and then by the time you fix everything else which makes the 305 a dog, why do all that when you could be doing it to 45 cid more?

 

How is doing that going to make it pass emissions? Tell us how yours failed, and we can probobly get you back on track.

 

Okay thanks, well the reason for switching the carb is because when I was trying to smog it it wouldn't pass because it was running rich. So I took it to get tuned and he made it worse.. So I took it again and it was the same problem.. I needed to use the car to get to school and I didn't have the time or money to get it rebuilt so I just bootlegged the smog, I know its bad but I was getting desperate. The emissions passed with flying colors just not the gas. So now my bro is giving away his alum intake and carb so instead of getting a rebuilt q-jet i'm getting a better carb? As for the msd distributer, he's giving that away as well so might as well kill 2 birds with one stone? As for the exhaust system that's just an extra. But yeah i'm not looking to build my little 305 to a race motor.. Just to make it a little bit more efficient for the little money that i'm putting in?

 

If you passed, then you are good for what at least a year? The reason you were advised away from some of the free parts is that your carb is computer controlled, and those have worked quite well in the 305's. Switching could make it better, but most oversize the carb and end up running worse than before. Also, careful on the MSD distributor. I take it thats one that runs off of a box and is stand alone? I run a 6-al with a pro billet, but my timing is locked out and not controlled by the CPU. If you switch all of that stuff out, you may run into a few problems. Its typically way worse if you had FI, but don't be shocked if it never really runs the same again.

By the way, you said emissions passed with flying colors, but not the gas...what does that mean?

 

If I passed it would be good for 2 years. Yeah because my q jet has been running really rich lately. Like I could smell the gas from the inside while i'm driving. I also have the option of usinge the new intake manifold and keeping my q jet while using an adapter for the carb. And the MSD distributed that I will be receiving is not the box.. It is actually a distributer itself with the MSD system built in.

Okay, on the smog test I took there were a few categories the car had to pass. One was how many bad air and emissions were coming out of the car itself and the other was how much gas it was letting in to the engine and actually using, since it was running way to rich it failed.

 

I'm not sure we're on the same page. MSD stands for multiple spark discharge. Its also their brand name, but all other companies that have distibutors with "the box" are running msd style, meaning not the same as points, or HEI. This set up uses a stand alone distributor connected to separate "box" connected to the distributor, battery, and keyed 12+ ignition source 12- being used for tachometer readings. It sounds like you have a MSD brand distributor that is a direct aftermarket replacement for a standard chevy HEI distributor. If so, it is important that all connectors are correct, or the car may not run correctly. The CPU adjusts timing according to signals being received from various sensors. Meaning you could be at say 5* advance at idle, but under load the timing could be corrected to 0* based on conditions.....that is a good thing. People with non stock motors typically have locked out timing, or set a base timing that is advanced by either vacuum or mechanical weights. If yours is indeed a stock style distributor and you just have the need to change it out...then you should be fine, if it doesn't appear like the one you have in there now....leave it be.

I am in a very strict state (AZ) for emissions...almost as strict as CA and the only things checked are fuel cap venting, Carbon monoxide in parts per mile, and hydrocarbons in parts per mile as well as all stock emission equipment being present. They typically put the car on a wheel dyno with sniffers in the tail pipe and check both idle readings and loaded (40ish MPH). At no time can they check how much gas is getting in the in motor, since that is effectively what the CO and HC readings will tell you. It sounds as if your Qjet needs to at least have the floats checked to be sure you aren't allowing fuel in faster than it can be burned...causing a rich scenario and a bad read.

 

Yeah it's a MSD brand distributer itself with the actual "multiple spark discharge" built into the distributer itself, so it eliminates the need for the seperate MSD "box" it's like a 2 in 1 distributer? How would I be able to know my motor can handle it or not?


Yeah in ca it's the same thing but that's what I failed, the smog guy even said its letting in too much gas for the motor to burn, causing extra harmful fumes. So I guess I can get it rebuilt and see how that works out, but can I still put on the intake manifold? And use my q jet with an adapter?

 

Do they do physical inspection of emission equipment, if so that settle the intake question? Unless that new intake has a provision for and EGR valve and solonoid, you won't pass.