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Posted: Sun Apr 27, 2008 1:23 pm Post subject: How do I know which carberetor is good for me?
As I've stated in another thread, I have an '82 Elk with a 305 from an '87 Firebird. It currently has a computer controlled Rochester Quadrajet, but I do not have the computer to control it.... I've heard both ways as to weather I should replace it or not, as I am only getting 11-12mpg, when I /should/ be getting closer to 15... And if replacing the carb will make up that 3mpg difference (as well as giving me a few more ponies under the hood) then I would say that getting a new one would be well worth it, and pay for itself in just a year or two...
I've tried looking around, trying to find what type of carb I should get, what I need... but really, there are so many options out there, with so many different specs and details, I have no idea what I should be looking for...
THIS Holley had caught my eye... but the Emission thing says it's illegal except for off-road applications? I'm looking for my elk to be a daily-driver during the summer... (A very pretty, nice running daily eventually)
I tried looking through the Edelbrock website, but they were woefully uninformative, and seem to be under the assumption that you already know what you are looking for...
I KNOW I want an Electric choke... And a 4-barrel, likely in the mid to upper 600 CFM... And I would like something that would add power, as well as efficiency if at all possible... though in the end, efficiency is what I'm going to have to lean to in these times...
And, one last part, I have also been considering putting in a turbo or supercharger, which would of course affect the carb decision... but I would like to know, do these technologies help with economy as well? Or are they purely for power?
Oh, and for the record, I do not want to upgrade to a 350, so don't say it
The computer controlled carb with no computer just runs full rich all the time ala poor mileage. You need to get a non- computer controlled from a chevy engine prior to the CCC stuff. 600 cfm Holley or Edelbrock on a 305 that is stock otherwise would be about max for it. They are usually set-up toward the rich side out of the box.
The Edelbrocks are easy to tune and the kit to do it with is not tooooooo bad.
Your best bet, in my opinion - they are like a-holes you know, everybody has one - is to find an early quadrajet. It is probably going to give you the best mileage and overall performance for the buck. Just find a good used one at the wrecking yard or off cough-cough ebay and have a good rebuilder go thru it for you. A properly set-up quadrajet driven normally on the highway should yield you 17 or better with a 305.
Try a private message to lkmeanobiker aka Tony he found a good source for qjets a while back.
Is your distributor still computer controlled with no computer to control it? _________________ 84 Elky with 455 Buick, Tremec TKO600 5 speed, 8.5 3:42 posi -
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Another 3 to 9 years should finish it.
I.... don't really know what the setup on my distributor is.... it works, so I haven't touched it... It does have wires going into it, besides the obvious sparkplug cables... so I'm assuming it is computer controlled, and if it works... well, it has to have the computer, right?
Wow, 17 mpg? That would be awesome Almost as good as my Oldsmobile... One question I have though, do non-computer carbs still have a connection point for the AC wire? I spent alot of time and money rounding up the parts to rebuild the AC system that was stripped from the car, and I'd like to still be able to use that...
Necoa #: 10934
Location: 15(AZ,NM)
Joined: Feb 03, 2008
Posts: 455
Year: 1981
Model: El Camino
Posted: Sun Apr 27, 2008 7:50 pm Post subject:
Dist. looks to be the non-CCC with vacuum advance so you should be good there. Although I would throw a timing light on it. Its either way out of time or off a tooth when it was installed. As for the carb. I agree with 464elky that a good running Q-jet is hard to beat. But....finding someone who can work on one is getting harder and harder. My prefrence is toward Holleys. I have the tools and parts to work on them and its easy for me. But anything in the 600-650 CFM range with vacuum secondaries should be fine for your application.
Although I would throw a timing light on it. Its either way out of time or off a tooth when it was installed.
Huh? Why? O.o Is there something you see that tells you that?? I brought it in for a tune-up the day after I bought it... and they checked the timing... though that was almost 2 years ago now....
Necoa #: 10934
Location: 15(AZ,NM)
Joined: Feb 03, 2008
Posts: 455
Year: 1981
Model: El Camino
Posted: Sun Apr 27, 2008 8:29 pm Post subject:
Your distributor is rotated so far clockwise the vacuum canister is hitting the transmission dip stick tube. You have no more adjustment that way, which should be for retarding the timing.
But, if the timing is off... shouldn't the engine be running horribly?
Back on the main topic for just a second.... Older rochester... what sort of timeline should I be looking for? 70's? 60's? Is there a particular car that had better ones than others?
Necoa #: 10934
Location: 15(AZ,NM)
Joined: Feb 03, 2008
Posts: 455
Year: 1981
Model: El Camino
Posted: Sun Apr 27, 2008 10:03 pm Post subject:
Looking at the pic I'm guessing the timing was too advanced and they retarded it as far as they could, that is when the canister hit the dip stick tube. They may have gotten the timing set. I'm just saying to check it. But, they may also have gotten it just to run. And if it has too much timing(cause there is no more to be taken out cause of interference), the distributor may need to be re-installed to get the timing set to specs. Too much or too little timing will make the engine run rough, but in different ways. Like I said, get a light on it and check it. Cant help you on the Q-jet, dont know much about them.
Necoa #: 7515
Location: 13(TX)
Joined: May 20, 2006
Posts: 117
Year: 1981
Model: El Camino
Posted: Sun Apr 27, 2008 10:27 pm Post subject:
I'd look for an early 70's Qjet if possible. I can't remember which years came with the hot air choke, but they're kind of a pain and I'd recommend making the switch to an electric choke.
They aren't really car specific, but I think that the BBC carbs were made to flow up to 850CFM whereas the SBC carbs were made to run at 750CFM.
Necoa #: 2321
Location: 15(AZ,NM)
Joined: Jan 30, 2004
Posts: 1169
Year: 1974
Model: El Camino
Posted: Mon Apr 28, 2008 3:03 am Post subject:
conquista90 wrote:
I'd look for an early 70's Qjet if possible. I can't remember which years came with the hot air choke, but they're kind of a pain and I'd recommend making the switch to an electric choke.
They aren't really car specific, but I think that the BBC carbs were made to flow up to 850CFM whereas the SBC carbs were made to run at 750CFM.
Other than measuring primaries there's no way to know how big a Q-Jet was without the carb number. It's usually stamped on the front of the bowl on the linkage side of the carb on the models I've seen. I still have my Q-Jet that came factory with my 74 and it was actually 795 CFM. I've seen numbers like 705, 750, 795, 805 and 850 CFM depending on application.
The sizing on mine might be due to the 400 SBC that came with the Elky.
_________________ 74 El Camino Classic - project car #1
96 Camaro - RIP, Traded 10-16-2007
2008 Mustang GT, It ain't a Chevy but at least it's American!
looks to me like he could move all the wires one position clockwise, move the distributor counter clockwise and be able to set the timing.. _________________ 84 Elky with 455 Buick, Tremec TKO600 5 speed, 8.5 3:42 posi -
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Another 3 to 9 years should finish it.
*headdesks* Oh lord... I was hoping the mechanic who put my car together knew what they were doing.... The main fan on the front of the engine was on backwards when I bought it... but that seemed like a simple mistake... now this too? Urgh, I wonder what else is wrong x.x
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Almost as good as my Oldsmobile... One question I have though, do non-computer carbs still have a connection point for the AC wire? I spent alot of time and money rounding up the parts to rebuild the AC system that was stripped from the car, and I'd like to still be able to use that...
Well..... that's an interesting bit of info....
