I want to get rid of all smog and crappy lookin/performing carb and swap in a holley or eldebrock. I know i will have to disable the ecu and maybe buy and msd ignition and stuff. my bud says its real easy but hes super busy. I have the smog pump belt off, dont have money for headers so when i remove the air lines that feed the exhaust manifold i will need to plug them with hardened bolts im assuming?? if anyones does this procedure before i would appreciate any tips. thx. 1984 Z28 305ho

 

Okay, you're going to get a very biased opinion here. So, you have been forewarned.

In my opinion, this is not "easy", let alone "real easy", nor is it smart. Having run the stock q-jet system for over 10 years, in various stages of modifications, and having had both non-computer, non-emissions q-jet and Holley experience in the past, coupled with all of the information available through various publications and the internet, I have come to the conclusion that the factory computer q-jet system is the BEST street performance system available. Whether or not it is "ugly" is a matter of taste, but again, I'm biased, and I am unashamedly a function-over-form guy (and personally think Holleys are pretty ugly).

Now, let's get to the nitty gritty. Neither an Edlebrock nor a Holley will bolt to your stock intake manifold. So, you'll either need an adapter, which will reduce carb-to-hood clearance; or you're going to need an aftermarket intake manifold. Yes, there are better intake manifolds from the aftermarket than the factory intake, but the gains without any other engine upgrades will be minimal, if any. So, just the fact that you're either using an adapter or changing the intake, in my view, already takes you out of the "real easy" world.

Next, the factory distributor won't operate properly without the computer, so you'll need a distributor with vacuum and mechanical advance. Not a biggie, as you'll be removing the distributor anyway if you replace the intake manifold, and they are readily available - but it is an extra expense. So, don't assume that the only cost will be the replacement carb.

Now, you didn't say what transmission you have, but if you have an automatic, the "throttle valve" cable, commonly referred to as the "TV" cable, needs a bracket attached to the throttle arm of the new carb to properly set up the geometry for the TV cable operation. Failure to do this will keep the transmission from shifting properly, and may even lead to transmission failure due to improper pressures inside the transmission.

In addition, if you have an automatic transmission, the computer will no longer have the input it needs to lock up the torque converter clutch when it should be. Stories abound of TH700's burning up the 3-4 clutch pack when the TCC isn't being locked up as it should be (as I discovered the hard way). So, you'll need to rig up some means to accomplish TCC lockup. Kits are available, but that's also an additional expense.

If you have a manual transmission, the above 2 paragraphs are moot.

You haven't yet said exactly which carb you would go with. This, to me, is just important as whether or not to change it out. Once again, in my opinion, the Edelbrock offerings are a downgrade from the stock q-jet. Without exception. There is nothing Edelbrock offers in their carburetor line that is better than the stock computer Quadrajet. Zilch. Nada. You won't be able to talk me out of that opinion. However, if all you care about is whether or not the carb looks shiny, then that is one advantage the Edelbrock does have.

Now, a Holley is a good choice for certain usages. Such as a car that is trailered to the track and only used for drag racing. I don't see that in what you've posted, but maybe that is your ultimate goal. Yes, you can drive a Holley carb equipped vehicle on the street, but for that application, it has zero advantages over the q-jet. If, however, you have a manual transmission, the Holley double pumper type carbs do have the advantage of helping your T5 live (speed shifting a T5 is a sure path to transmission death). Regardless of your transmission type, though, I have as much respect for Holley vacuum secondary type carbs as I do for Edelbrocks - they don't, in my opinion, belong on a performance car, regardless of its use (with the possible exception of a high-power, tire-limited class race-only car, where you need to bring power on slowly in order to maintain traction off the line). So, unless you are considering a double pumper carb, in my opinion, you're better off with the q-jet. And, unless this is a race-dedicated car, I would say anyway that you're better off with the q-jet.

Assuming you're still set on going down this path, you still have tuning ahead of you. Regardless of what anyone says, no carb is tuned correctly out of the box. Yes, they come with instructions, but "How do I get my Edlebrock carb to run right?" and "How do I get my Holley carb to run right?" topic threads litter this forum. There are some people who are very good at doing this (and I don't consider myself among them), but to really do it right takes equipment the typical do-it-yourselfer doesn't have. You can get it so it runs acceptably without it, but you won't be able to match the stock q-jet performance without it.

Did I mention the stock air cleaner won't fit a Holley or Edelbrock without modification?

Okay, that's a lot of words, and a lot of opinion. But, other than "crappy lookin/performing", we don't really know what you're trying to fix. If it's looks, then go get a 600 CFM Edelbrock and have at it. If it's performance, then more details are required. Basically, though, the stock q-jet can be rebuilt to perform quite well, and look good as well. Quality rebuilds are available, and although some problems with rebuilds are reported here, I'm suspicious that most of the problems were caused by the installer (typically the owner), rather than a problem with the rebuilt hardware itself.

To get a stock q-jet to run properly requires a clean, properly adjusted carb, a means to set timing and the MCS dwell (a dwell meter, or the ability to monitor the data from the ALDL connector), and all the input sensors operating properly (O2 and coolant temperature sensors primarily - the throttle position sensor is built into the carb). The factory specs will do just fine. Changing the secondary hanger and rods will typically improve WOT performance (changing the secondary hanger and rods is easier than tuning an Edelbrock, often touted as the easiest non-computer carb to tune). The real kicker is that you should be able to accomplish this for less money than swapping to an Edelbrock or Holley (assuming you buy new parts for the swap - if you get stuff free or through sweetheart deals, that doesn't count).

I'll give you a little bit of my own experience with the computer q-jet, then I'll shut up. I started with a stock '86 LG4, swapped into my '82 Berlinetta. All of the equipment was swapped over from the donor car, including the exhaust. It passed emissions with no issues. After a couple of years, I added aftermarket heads, intake, cam, headers and exhaust to the 305, it still passed emissions. After the car was exempted from further emissions testing, I swapped in a 350 shortblock with ZZ4 crate engine cam, keeping the heads and rest of the q-jet operating system. I occasionally took it to the drag strip, where, with insufficient stall and highway-oriented gears, it would run 13.4's in the quarter (at sea level - most of the track time was at higher elevation, where it ran low-14's) - it wasn't optimized for the track, but it was still respectable. I did try a Holley q-jet replacement double pumper carb on it, which I found did not improve drag strip performance (unlike my non-computer q-jet to Holley, and vacuum secondary to double pumper Holley experience), and wasn't as good on the street.

So, now you have my opinion. While I'm not saying you're on your own if you continue with the carb swap, I think I have a good case for saying you'd be better off if you stuck with what you have, based on the limited information you've provided.

 

i can see the value of fixing what you have but, screwing with the pcm and messing with the timing with a dwell meter and keeping o2's working and old wiring. its endless.

its a pain to change over but after that its so much easier to set timing and make adjustments to the carb without having the pcm fighting you. you can get the 70's style hei complete with a decent cap and coil for a few bucks from the jy and putting a non emissions intake on it is easy. the 700 is a little bit of a pain, but there are kits

 

All I can say to that is, during the 10 years I ran the CC q-jet, I did not have one single item die or go out of adjustment. Except the choke pull-off, which is NOT specific to the CC part.

On the other hand, in the car with the Holley, I was constantly fussing with something or another on it at the track between rounds. Constantly.

 

WOW!!! +1 for 5.7kid!! So true!

Seriously.

 

the first time or two you run it, it requires tuning but not really that much besides that. unless you change something with the car and need to retune

 

wow thx five7kid tons of info. i had no idea about the tranny/distributor/ecm thing but I get it. i havent really done much to it in years, as i just got the car return to me after being in someone else possesion for the last 13 years. Quite a story actualy. Anyways im just gettin back into it so theres some things i forgot haha. Sounds like its just going to run with the stock gear till i get all the body work done. Thx for the help man. Btw its got the 700r4

 

Yep. His info is the only reason I've kept my QuadraJet on my L-69, but it has not been maintenance free.

In NY and TX I had dealer mechanics tweak it, and they swear up and down the choke is good, etc. (choke light sometimes flickers while idling), but the check engine line always comes on/off while cruising on the highway, cold starts suck and the gas pedal usually has to be held for a while to keep it running until the temp goes above 100 degrees. Vapor Lock sucks after I stop for 20 minutes and go to fire it back up.

I could go on and on, but the dealer mechanics say it's normal. I'm about to chuck it across the street and install a F.A.S.T. TBI kit.

Maybe if there was an actual Q-Jet expert around to check the dealer's work or someone to educate me on what the real problem is, I'd be less frustrated, but right now I hate carbs. So I agree with Five7Kid, but I see your point on wanting to go with a simpler carb. Because I'm cheap and refuse to let this car win I'm sticking with my Q-Jet - for now.

An LSX is in my distant future.

 

Since the OP isn't paying much attention to this thread...

I'm curious, did you check out your alternator? The choke light shouldnt come on at all.

 

I haven't replaced it recently. While it's driving there isn't an issue, but because I'd occasionally have the battery tested and it came back as having "bad cells" then I'd swap the battery for a new one. This last time I went with an Optima red top. I used a harbor freight cigarette tester and the alternator checked ok. I know, real scientific. I'll try replacing the alternator. The issue started about a year after the alternator and a battery were swapped, so I assumed the alternator was good. Thanks.