Kornis

Hello Everyone, New to these forums and wanted to introduce myself as well my question.
I recently purchased a 1986 IROC Z28 that is for the most part in great consition for a 26 year old lady that has been riden hard. It has a 305 4BBL engine with a 5 speed manual, 373 limited slip rear. Everything is completely original. I purchased this as weekend runner, not an every day car, but would like to be able to drive it if needed. I tagged the car as a CLASSIC so I do not need to ever get the emmissions tested, just yearly safety inspections.
My question is as follows, If I change the intake and carburator to a non CPU controlled carb, and put a good vacum advance distributor in it. Do I still need to keep the computer in the car. I also plan on changing the exhaust to something a little more deep sounding and louder. I plan on upgrading the engine later on but it only has 100k miles on and runs great except it needs a new carb.

With these minor changes, would I see any improvemnt in it, or should save up for ayear or two and just get a new engine alltogether.

Damon

Welcome to the board!

You can certainly do that- many have. I personally leave the computer and it's wiring harness in place in case I want to change it back, but others have removed it for underhood cleanliness reasons.

You can also remove the underhood air pump (smog pump) system and all the lines that go to the exhaust manifolds and cat converter (and plug them so you don't have an exhaust leak). That cleans up the look underhood WAY more by itself than removing the various computer-controlled stuff and related wiring.

If you're going to do the exhaust you might as well do it all. 3rd gens had some pretty bad exhaust on them from the factory. Everything has to go from the manifolds to the tailpipes. A set of shorty headers, matching 3" y-pipe, aftermarket 3" cat and 3" cat-back system is the most common upgrade path and it works. They all run better with the exhaust uncorked, even the L69 HO cars that came with the bigger 2-3/4" exhaust from the factory (the low output LG4 used a little pea-shooter 2-1/4" exhaust system). Just look at the factory y-pipe (or, as I call it, the 'T' pipe) and you'll see what I mean. I like the Hooker shorty setup with 1-5/8" primaries and matching y-pipe, personally (reliable, good ground clearance, easy to assemble ball-type unions to the y-pipe that don't have gaskets to blow out, etc.), but there are many choices out there. Since you'll be ditching the smog pump you don't need to buy the more expensive set that's got the air tubes built into it.

I suspect your engine is the L69 HO motor because I think they were the only ones that could be had with the 3.73 rear gears from the factory in those years, but don't quote me on that. Regardless, the exhaust is still pretty bad, even on the L69 cars. Exhaust upgrades will pay even bigger dividends when you put a stronger motor in it later.

five7kid

iTrader: (14)

For the carb/distributor/computer part, you would see zero improvement over the factory system that's operating properly. It's probably the most common question on this Carburetor forum, and it seems to be nearly impossible to convince people that the factory system works better than the non-computer systems, providing all of the power of the older non-computer systems.

As for exhaust, I agree with the Hooker shorty recommendation, but the ones with the A.I.R. tubes, 2055HKR, are the only ones that come with (or have available) a good Y-pipe. Nobody else's shorty/Y-pipe combo comes close to the 2055's.

Cam and exhaust (and air cleaner if LG4 - since yours is an '86, I seriously doubt it's an L69) are what are really needed to wake up a 305.

The '86 computer q-jet system is fine with a 350. Ask me how I know (or, cheat and look at my vBGarage...).

Kornis

Everyone is recommending the Hooker 2055HKR for the headers because of the Y-PIPE. I am doing away with the single exhaust altogether. Can you buy these headers without the Y-PIPE. No sense in buying the Y-PIPE if I am not going to use it. I am not going to be putting the A.I.R. tubes back on either

Ozz1967

iTrader: (4)

Since you don't need them, have the air pipes ground off and welded shut before coating/painting your headers. Sadly, the 2055's don't come without the AIR tubes, not that I know of anyway. This will make it much, much easier to work with your spark plugs.

five7kid

iTrader: (14)

If you aren't planning to use a Y-pipe (which you didn't happen to mention in your original post), then either the Hooker 2460HKR or Hedman (several Hedman choices - 68470, 68474, 68479) will do. You'll be fabricating all the pipes from the collectors.

Or, since you aren't going with a legal system anyway, might as well go with Hedman long tubes, 68460. Ground clearance will suffer, but that would be the case with duals from shorties as well.