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 (http://www.holley.com/0-80670.asp) 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 :P

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?

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? :P

PICTURE OF MY DISTRIBUTOR (http://i137.photobucket.com/albums/q226/Midnight_Fenrir/Car/IM000326.jpg?t=1208131994)

Wow, 17 mpg? That would be awesome :D 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...

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....

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.

8O Well..... that's an interesting bit of info....

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?

Something like.... THIS (http://cgi.ebay.com/ebaymotors/ROCHESTER-QUADRAJET-CARB-17059206-REBUILT_W0QQcmdZViewItemQQcategoryZ33550QQihZ002QQ itemZ120251566495QQrdZ1QQsspagenameZWDVW), perhaps?

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.

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.

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.

:D
:D

Here is a link to a post that has a link to a qjet info site I found a few weeks ago.

Here (http://elcaminocentral.com/ftopict-25093-quadrajet.html)

From that pic, looks to me like the #1 and#8 wires are backwards.

Good call Kyle. I missed that one. Those wires are definatley not in the normal position on the cap.

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..

*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

Richard, now you know why we love pictures. We can just scare people to death and pick it apart. LOL Nothing serious with the distributor but I can see where you might get a little concerned. Anybody that would leave the distributor that way would make me wonder too. :-P

Okay... I don't get it... the Distributer is a very important part of a car... how can it being that messed up not be a problem? 8O I don't really know that much about the workings of engines, beyond the basic concepts... but doesn't timing being off mess with proper ignition? Couldn't this be causing catastrophic damage to the inside of my cylinders?


Another quick question about carbs... getting one that lets in more air than I need isn't a bad thing right? It's the engine itself that actually draws in the air, so it won't get anymore than it needs, right?

It's possible to have the wires be one off and still start the car. Usually the distributor timing will be set extremely retarded or advanced. It depends on whether the wire position is off clockwise or counter-clockwise.

With #1 and #8 being so close in the Chevy Firing order: 1 8 4 3 6 5 7 2 with the #1 and #8 positions being right next to eachother on the cap. THey have Distributor caps that can reorder the wires so that 1357 and 2468 exit on the side of the engine they correspond to instead of having all that crossover stuff going on.

Anyway it's possible to have a running engine (not running well, mind you) that is set up completely wrong.

As for the bigger carb (CFM) question. While the CFM rating is based on airflow through the carb and into the intake manifold more is not necessarily better.

Most stock and mildly modified Small block chevy's will do just fine in daily driving with less than 700CFM. With stock engine components a bigger carb (750 where a 600 used to live) will actually run worse than the smaller one it replaced.

That's because an engine is an air pump but is restricted by things like airflow through the intake, the size of the intake and exhuast valves, the size of the combustion chamber in the cylinder heads and the type of exhuast system (manifolds or headers)

Think of it like a dam on a lake with spillways for releasing water when the water level behind the dam gets too high. The bigger the dam the bigger the lake is behind it. Now imagine that there's two dams with the same sized lake behind them. They are identical except that one has two spillways and one has only one spillway.

Now imagine a big thunderstorm has come along and made the water level behind the dams very high. We're going to have to get rid of the water fast or it will spill over the top of the dam and flood the El Camino store and we won't be able to get parts anymore :)

The dam with two spillways can release more water more quickly because it has the ability to get rid of water faster than the dam with one spillway. You could say this is a high performance dam.

The dam with one spillway has the same amount of water but only one spillway. So the guys who work in the dam are sweating pretty badly because they can't get rid of the water as quickly as they'd like to. In a normal thunderstorm the dam with one spillway would work out just fine but this is a BIG thunderstorm so no matter how much the guys who work there would like to get rid of the extra water they can't because they don't have adequate spillways to release it to.

Think of the lake as the air, the dam as the carb and the spillways as the engine and exhaust components. You can put on a big carb but if theres not enough capacity to get the air out of the engine will run poorly because of the bottleneck caused by the restrictions in the downstream engine components.

I know it's an imperfect analogy but I felt like telling a story....'
:D

Hahaha, imperfect or not, it was kinda unnecessarily complicated too :P But I do understand what you are saying. I was thinking of upgrading the exhaust at some point as well... But I don't know if that's something I can afford at the moment.


So, I'll set up an appointment to get that Distributer looked at... I don't have the proper tools for tinkering with it at this point, nor the knowledge base...

But on to some Carbs I'm finding on eBay...

HERE (http://cgi.ebay.com/ebaymotors/ROCHESTER-QUADRAJET-CARBURETOR-ELECTRIC-CHOKE-305-ENG_W0QQitemZ370046680005QQcmdZViewItem) is an electric choke for a 305... but it doesn't say what year it is, or weather it is CC, though if the immage matches the unit as it says, it doesn't see to have the connection points...

HERE (http://cgi.ebay.com/ebaymotors/REBUILT-CARBURETOR-1973-PONTIAC-ROCHESTER-QUADRAJET_W0QQitemZ310044664265QQcmdZViewItem) is an early 70's, with all the bits and pieces I need... but I think it is a mech. choke by the picture... Can an expert help me with that? Also, it may let in too much air, since it is for a 400-455 engine...

But THIS (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140228264075&_trksid=p2759.l1259) seems to be the best choice I see, again built for a 305/350, and has an electric choke. Already rebuilt and nice and spiffy. With no computer ports to be seen :D

The first one looks like it is probably what you need. It seems a little high priced because they are charging you for all the "make it pretty" stuff.
The second one is not what you are looking for. The choke uses a heat pipe which your engine doesn't have. It could be changed to electric but you also have to watch the bases on going from Buick Olds Pontiac to Chevy as they treat the manifold heat differently and therefore use different base gaskets.
Keep looking is my opinion.
Here is a link to a page with them in stock for a little less money. the bottom item in the top table I think is what you are looking for.

Here (http://www.guaranteedcarbs.com/cgi-bin/shopper.cgi?search=action&category=CH48&keywords=all)

Well, the $280 is just the buy-it-now price on that first one... Depending on what their reserve is, I could probably get it for significantly less... And, if it is what I am looking for, it might not hurt to bid and play it out to see if I can get it for less than on that site :P

But looking on that site you provided.... there's a +$78 fee if I don't send in my old carb... which I have no problem doing, but they want the same model they ship me?? I sent them an e-mail to ask about it...

You might consider the 650 holly spreadbore as they are a bolt on replacecent for the Q-Jet.

You might want to look into the Holly 650 spreadbore carb. It is a non computer controlled direct replacement for the Q-Jet. The 650 cfm carb migtht be a better match for his eng.

While we are on this thread, ( the Q-Jet link was awesome, thanks !) does anyone know if there might be a way to "cheat" a comp. controlled Q-jet by jumping any of those terminal wires/connections going into it ? Maybe re rout some vacuum lines ? Like to make run normal (lean it out) ALL the time ? Hmm. :cool:

You might consider the 650 holly spreadbore as they are a bolt on replacecent for the Q-Jet.

That's what I was originally looking to get actually... but in my thread, " Questions on a non-stock 305.... (http://elcaminocentral.com/ftopict-25021.html)" I was told: Stay away from the Holley Q-Jet replacement. Its a POS. >.> And, as it turns out, more expensive than a rebuilt Rochester.



Okay, I got some important questions that need answering... on these mechanical carbs... there doesn't seem to be an electrical hookup for the AC cutoff switch... (I don't remember exactly what it's called anymore x.x) Does this mean, that by going back, I'm loosing my AC? Or is there a way around this?


When i go to take the carb off... how do I keep stuff from falling into the engine? I dont know, but it seems like parts and bits of the gasket might fall in if it's worn out... or is that something I shouldn't need to worry about, and be able to just put a lint-free cloth over the manifold.

I had one of those Holley Q-jet replacements once. Did not have good luck with it. I would not recommend one. As for the junk in the motor. If any gasket material falls in, use a shop vac and clean it out. Then use some clean rags to stuff in the manifold till your ready to mount the new carb. Dont think you can cheat the on the carb connections. As for the A/C switch. The only one I can think of is a selinoid(?) that kicks up the idle a bit when the A/C is on. Should not be an issue with the R-4 compressor.

Yeah, that sounds right... both the name of the connection, and the compressor type.... I'm 98% sure R-4 is what I installed. So, the system should still work?

Heh, shop-vac... an obviously simple solution XD I was kinda worried about something falling right into one of the cylinders, but it isn't a straight shot from there, is it...

The high idle switch gets a signal from the hot wire to the A/C system. It wont change how or if the A/C system works. The only thing it does is kick up the idle speed when it gets 12 volts. If you disconnect it the A/C will still function as it should. Just tape off the end of the wire so it doesnt ground out when the A/C is on.

The high idle switch gets a signal from the hot wire to the A/C system. It wont change how or if the A/C system works. The only thing it does is kick up the idle speed when it gets 12 volts. If you disconnect it the A/C will still function as it should. Just tape off the end of the wire so it doesnt ground out when the A/C is on.

Huh.... alright, good to know... at least I don't have to worry about that little detail anymore :D

Grrr... They still haven't responded to my e-mail about the core return policy... Guess I have to start looking elsewhere....

...while this thread is still living, no carb Einsteins anywhere out there that can suggest any ideas on how to hot-wire an EEC QJet in order to lean out the bastard ? - just trying to help a kid on a low budget - :(