Hi, I have a 1983 Z28 bone stock all original, has the 4 barrel 305. Over the winter I am putting a 650 holley on it, single feed, electric choke, vaccum secondaries, is this too big for my 305? Also what horsepower gains can I expect with this new carb, a new Edlebrock aluminum intake and a new 110 gph fuel pump? Thank you.

 

If your QJet is working correctly there is little or nothing to be gained. Also, if you ditch the computer controlled QJet you also have to ditch the computer controlled HEI distributor and replace it with an earlier non-computer controlled one.

 

thanks for the help, I'm going to summit racing to get all of these parts soon and was thinking about getting a non-computer HEI as well, if that will help the performance than thank you, I just don't wana go crazy with a new engine, just looking to get some more power from some bolt-ons.

 

If you don't replace the computer controlled distributor when swapping from a computer controlled carb to a non computer controlled, then your timing will no longer be able to advance. This means poor performance, gas mileage, and an absolute dog of a motor. If you're looking for easy and cheap bolt on upgrades to increase performance, stray away from upgrading your carb and intake, assuming there is nothing wrong with the qjet as Damon stated. You will not find a better carb and intake for your application than the qjet.

You're better off focusing on the weak areas or the bottle necks in performance. The main one being the exhaust. The money that would otherwise be spent on a new carb, intake, distributor, and miscellaneous will give you a good jump start at saving for a good flowing exhaust.

 

I agree with above. If things are working good for you with the original carb then don't change it. You can get better bang for your buck by doing the following.

Up grade your exhaust - This is highly restrictive and you will get better results just by doing this.
Get a good distributor cap, rotor and low resistance rotor button. Also the ignition modules on these HEI's can be problematic. Have yours checked for full functionality. My borthers 86 didn't set any CELs but his module had a bad channel causing spark scatter above 4K RPM's.
Get a good set of plug wires and plugs especially if the wires are older than 10 years old.

I love my aftermarket stuff but I had a bunch of stuff sitting around to start with like a manifold, Holley 600, old HEI dist. Crane Cam and a complete SLP Tri-Y exhaust sitting around. Also my Q-jet was not working right. For me I was only out my time and the price of a new complete engine gasket kit and a new harmonic balancer. I don't drive my car often and I get worse gas mileage with my upgrades than if it was still stock. Not complaining just stating fact. I also wanted to get my car into the 14's at the strip with what I had laying around

IF you are making any mods please check your balancer and replace it if the elastomer ring is cracked of damaged! I've seen harmonic balancers explode and they will leave nasty holes in body panels and or oil pans

 

The only reason I wanted to get a new carb is because I can tell the Q-jet is worn out, I mean it's 30 years old and the kid I got the car from busted the choke off the carb so it doesnt want to run right sometimes, the new carb distributor and intake are only going to run me about 600 at summit, which I can very well live with. So if I replace the distributor too along with the carb then everything will work out right?

 

Replacing the distributor with a non cc older style HEI will do the trick. But, before making a decision reconsider this: Is $600 verse the price of a qjet rebuild kit and a new electric choke housing/coil with no noticeable power gains and worse gas mileage worth it? That $600 will get you a decent set of headers, a y pipe, and maybe even a little extra to save toward a cat back exhaust and you will see a performance increase that you are looking for.The $ to performance ratio just isn't in favor, but if that is what you would like to do then by all means you will get a world of help from all of us if you need it.

 

Thank you, I should have mentioned before that the car already has a flowmaster exhaust on it with an a/c delete and smog delete so i'm really getting all the power gains that I already can without turning to more bolt-ons, I would go all out but last year I sunk a lot into a 383 stroker for another car and it didn't work out so I'm trying not to go down that road again, I just joined this website and this is the first camaro I've ever owned so I really appreciate all your guys input and advice.

 

I'd rebuild the Qjet, would be cheaper long run and you don't have to buy a new distributor which will save you money. Also, with the Holley, your gas mileage will get worse and you won't get much, if any of a "power" upgrade over the qjet.

 

Well I think everyone has covered keeping the Q-jet now so if you are set on swapping carbs do not get a 650cfm carb for that 305. Even a 600-570cfm is too much for a 305 but it will work. Personally, when it comes to aftermarket carbs, I prefer Edelbrock for street use and Holley for street/strip, racing use.

The biggest problems I see is that people don't know how to tune a carb and they get themselves into trouble thinking just slapping a carb on there thinking that will do the trick. Read up on the type of carb you would like to get first and know how it works and the tricks to get it running better.

Get a GM HEI from '79 or older car. These are non-computer controlled distributors and they have one hell of a coil for spark energy. Make sure you have a good cap, rotor and low resistance rotor button. You might even want to replace the ignition module in the dist as well.

At this point you can remove the ECM and ECM harness from the vehicle and remove the service engine soon bulb from the dash as they are no longer used.

Get a lower temperature fan control temp sensor switch for the passenger side head or install a switch in parallel with the temp sensor with the other side of the switch tied to ground to manually control the fan as well as automatic.

 

The carburetor is the last upgrade you make to a 305. You do that the same time you start trailering the car to the track because it is undriveable on the street.

Really, this is the wrong way to go. The reasons are numerous, most of which have been covered.

You have an automatic transmission, which has a lockup torque converter that is controlled by the computer. If you change the carb and distributor (obviously, as stated, you need to change the distributor if you go to a non-computer carb), the computer won't have the input it needs to operate the torque converter clutch. If you run the car at highway speeds without the lockup function, the 3-4 pack will overheat and eventually stop functioning. There are kits that will provide that function without the computer, or you can wire it up yourself, but don't leave out this part of downgrading to a non-computer carb. Lockup kits are about $75. Don't forget you also need a geometry corrector bracket on the throttle arm of the Holley for the TV cable (without it, same as results as no lockup).

Not sure what you mean by the choke was broken off, but even if the carb is FUBAR'd, you can get a rebuilt computer q-jet for less than the Holley/intake/distributor/lockup/corrector is going to cost you. And I'll come right out and say it - the Holley will NOT run better than a properly operating computer q-jet.

 

Well guys... even if the OP hasnt picked anything up out of this thread I certainly have. I have virtually the same exact car (minus the flowmaster) '83 Z28, all stock, and had virtually the same thought process with slight variations (Edlebrock vs Holley).

I had thought of the full list needing replacement (brackets, lock up switch, dist, etc etc) only mine seems like it would be even worse to tear it all down. My carbs only ailments are the choke not quite working 100% and occasionally the secondaries sticking shut first thing in the morning. In the summer the car runs great, in the "winter" (quotes for a Florida winter, not New England winter) it starts a little rough, but smooths out after 10 minutes or so. Basically, there really isnt much wrong with the car at all and I just got annoyed at having to baby the throttle in the morning.

After reading through this thread, Im convinced I was looking down the wrong road. I am now going to look into a local guy who came highly recommended at rebuilding and tuning carbs and then upgrade the ignition to help with the harder starts (coil, rotor, cap, wires)

I agree 100% that a rebuild of the carb and money spent in exhaust are much better than replacing everything. If the car already has a Flowmaster on it, how about the rest of the exhaust? Does it have headers? If not, the manifolds and the Y pipe are the 2 biggest restrictions on these cars, even more so than the catback portion. That will give you something you can feel even in the buttdyno.

 

QJet choke problems are very common. Probably one of the most common things that goes wrong with them. Unfortunately, not everyone knows how to fix them. Starting with..... is the wire plugged into it?? Does that wire have full 12V??

The choke element itself can go south over time. Just check resistance to ground between the electrical connector on the choke (wire unplugged from it) and a ground (body of the carb will do fine). Do this at "room temperature". A fresh choke element will have about 5-10 ohms resistance. A good used one about 10-15 ohms. Anything over 20 is shot.

And, of course, the vacuum break (pull-off), whether it's one or two, has to hold vacuum and move in and out like it's supposed to.

If you're messing with choke settings before you address those things, you're headed for trouble. There is very little that can go wrong with the choke system on a QJet by itself. To really botch one up almost always requires a "low-information mechanic".

 

Oh, I already have played the wire game with it. When I bought the car, the Choke light was on constant. Found it was a bad relay. So now its getting power and does open, I dont think it's quite shutting all the closed and thats my problem. I tried "adjusting" the connecting rod as per the QJet manual found here in the forums, but that didnt seem to help much. I think I need to replace the choke spring entirely. Anyhow, not trying to hijack the thread from the OP.

 

You really can't get anything "better" than GM's HEI coil and the only reason you would want to get a different one is if your coil is breaking down and not working properly. Your best ignition mod would be good cap and rotor, low resistance rotor button, and good wires. Not much else is needed.

 

Thanks for all the help guys, after listening to your inputs I think im going to rebuild my quadrajet if I would have to go through all that other trouble I appreciate the advice because as I said this is my first camaro.

 

Here is a good article to get you started

http://www.carcraft.com/techarticles...d/viewall.html