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I thought this would be a fun topic to discuss so here it goes. First I will admit I have a bias towards carbs but I have my reasons. The way I see it, this is how they stack up:
Carburetor Pros:
1. Adjustable
2. Can make more power than EFI
3. Cheaper
4. Highly modifiable
5. Simple
6. Can use a mechanical fuel pump or electric fuel pump
7. Can be rebuiltCarb Cons:
1. Harder cold weather starting
2. Typically will get less fuel economy than an equivalent EFI setup(though this is not always the case)
3. More parts to go wrong
4. Some cylinder wash can occur when choked
5. Requires more maintenance
6. Can muck up emissions controls if car is equipped with them(one of the reasons carbs and leaded fuel went away)EFI Pros:
1. Better fuel economy in most cases
2. Better atomization of fuel leading to better cold starting
3. Stochiometric ratio is much closer to 14.7:1
4. Requires little to no maintenance
5. Play better with emissions controls such as catsEFI Cons:
1. Not adjustable without programming and not to the same extent as carb
2. Requires a higher fuel pressure hence needs an electric pump
3. More costly
4. Hardware cannot really be modified
5. Less power than a carb(as long as the carb is tuned correctly and everything is functioning as it should, ignition timing must also be in the right spot for the carb to make the power)These are just some basic pros and cons that I could think of off the top of my head. I think carbs are superior as long as they ain’t strangled with emissions controls. A carb allows you more tuning freedom and is fun to rebuild(at least for someone like me!)
What do y’all think?
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I just finished up a mechanical rehab on a very low mileage but very neglected 50s gm vintage car for a customer. When I was done with, and I took it on it’s final test drive, the purring the 371 engine, the solid Thunk of the door, the chromed plated dash cluster, the 360 degree visibilty, and the way it glided down the road in all its ancient glory made me realize the same thing you just said, these things, they were far superior to anything made today.
[quote=”andrewbutton442″ post=124883]I just finished up a mechanical rehab on a very low mileage but very neglected 50s gm vintage car for a customer. When I was done with, and I took it on it’s final test drive, the purring the 371 engine, the solid Thunk of the door, the chromed plated dash cluster, the 360 degree visibilty, and the way it glided down the road in all its ancient glory made me realize the same thing you just said, these things, they were far superior to anything made today.[/quote] Thats really cool! Ya not to turn this into an old vs new thread(which we already have one going on the forum) but you are right, visibility is also better on older vehicles because the A pillars and such didn’t have to be just so for safety. More glass was used(however, on the pacer this was overdone) and it was easier to see what was around you as a result. I also had mentioned in another thread that the steel used was also better and thicker. It wasn’t just better because it was thicker, it was chemically more stable and pure/resistant. In any case to bring this back on topic, I looked at the price of injectors for a friends vehicle for shits and giggles and I saw about $900 for 6 injectors OEM for parts alone. This price plus the cost of a fuel pump sending unit($400) alone without labor puts the fuel system at $1,300. By comparison, a carb will cost anywhere from $70-$500 as a rough range of numbers depending on what type of carb, new or used, and what source you get it from and a mechanical fuel pump will only set you back $60 or less again depending on a few factors. Carbs are FAR cheaper.
I dunno about you guys singing the praises of the Qjet. For a long time I had two cars with that carb and while I could make them work, a month or two later I was always into them again. It was either an air motor or the choke had to be reset. The carbs on the cars I owned had bimetallic springs in the choke and they had to be adjusted for every season. Once all that was working the secondaries would either refuse to open or open too soon and bog the car. It was always something.
The day I bought my ’78 Trans Am I was so proud. I was moving up from a 170 cubic inch Ford Maverick. My wife needed to go to her place of business so I offered to drive. One the way home the Qjet dropped the float. It would still run if you kept it floored. So stop for a light in neutral and then yank it into gear – fun trip. The first day I owned this new car I had the carb apart.
[quote=”barneyb” post=125026]I dunno about you guys singing the praises of the Qjet. For a long time I had two cars with that carb and while I could make them work, a month or two later I was always into them again. It was either an air motor or the choke had to be reset. The carbs on the cars I owned had bimetallic springs in the choke and they had to be adjusted for every season. Once all that was working the secondaries would either refuse to open or open too soon and bog the car. It was always something.[/quote] I’ve never had a problem with the secondaries on mine. It’s all about the adjustment. Keep in mind, the Q-Jets secondaries are part mechanical. How much air the secondaries get is also load/vacuum based. The vacuum diaphragm is supposed to keep the air flap for the secondaries closed until the vacuum drops when the engine is loaded and the throttle is at a certain point in it’s travel. Andrew maybe you can explain it better to him, I ain’t the best at explaining things unless I am holding the carb right in front you and able to show you how it works firsthand B)
Here is my quadrajet in all its black magical glory. Notice the vacuum can near the choke? Thats what I’m refering to. If it’s busted you will bog.
Well, that is old history. I even had a book on Qjet tuning and fooled around with various metering rods and things. The point is, in the years of cars I owned with Qjets they seemed to be pretty much junk. Like everything else they may have had good years and bad years. Catalytic convertors and other emission equipment was required in 1976 so a lot of things under the hood were in flux. The cars had an amazing amount of vacuum hose.
[quote=”barneyb” post=125031]Well, that is old history. I even had a book on Qjet tuning and fooled around with various metering rods and things. The point is, in the years of cars I owned with Qjets they seem to be pretty much junk. Like everything else they may have had good years and bad years. Catalytic convertors and other emission equipment was required in 1976 so a lot of things under the hood were in flux. The cars had an amazing amount of vacuum hose.[/quote] Possibly your bad experience was due to the emissions controls, I don’t have to deal with that junk and the carb itself is presmog(1970). Emissions controls ruined the Q-Jet and many other good factory carbs.
Once set up correctly, Quadrajets have always worked well for me and the gas mileage (unless the foot is buried) will often be better with a QJ than a 2 barrel.
Regarding secondaries not operating, there’s a tiny pin that can sometimes get dislodged a tiny bit. If the choke is not operating properly that pin will lock the secondaries out.On Qjs that used the exhaust crossover to heat the choke spring, a lot of problems there were due to a sooted up passage in the carburetor. Exhaust gas could reach the choke housing but unless manifold vacuum was able to suck that gas through the choke housing and into the intake via the carb body the choke would not heat up as it should and choke operation could be very, very erratic.
People rip on contact point distributors. I’ve heard countless times that “points have to be replaced every 3 to 5 thousand miles”.
Only if the job is not done right. If the ballast is correct, dwell is right, and distributor cam lube is used on the dist. cam lobes a set of points should last 25 to 30k miles.As to GM’s HEI distributor; the best electronic ignition ever I think. Compact, simple, and near bulletproof. 🙂
[quote=”Bluesnut” post=125040]Once set up correctly, Quadrajets have always worked well for me and the gas mileage (unless the foot is buried) will often be better with a QJ than a 2 barrel.
Regarding secondaries not operating, there’s a tiny pin that can sometimes get dislodged a tiny bit. If the choke is not operating properly that pin will lock the secondaries out.On Qjs that used the exhaust crossover to heat the choke spring, a lot of problems there were due to a sooted up passage in the carburetor. Exhaust gas could reach the choke housing but unless manifold vacuum was able to suck that gas through the choke housing and into the intake via the carb body the choke would not heat up as it should and choke operation could be very, very erratic.
People rip on contact point distributors. I’ve heard countless times that “points have to be replaced every 3 to 5 thousand miles”.
Only if the job is not done right. If the ballast is correct, dwell is right, and distributor cam lube is used on the dist. cam lobes a set of points should last 25 to 30k miles.As to GM’s HEI distributor; the best electronic ignition ever I think. Compact, simple, and near bulletproof. :-)[/quote] Ah yes, the choke lockout pin. It is there to prevent the secondaries from opening when cold. It can get stuck as you said and prevent them from opening all the time.
My setup uses that line that you see to heat the spring without exhaust gases..it simply acts as a conduit for the heat from the exhaust to travel. Works for me!
As you can see I have an HEI dizzy…they are amazing, however I do still like points systems and can tune them as well.I prefer GM points distributors over HEI stuff. Hei can be made better, with a remote coil, better module, recurving, but its work to do it.
One of my sons owned a 1988 Camaro with the 305 and TBI. We bought that as a college car for him and it was such a good car and so reliable he kept it and drove it for years after graduation. Almost 300 thousand engine and trans never touched with no oil consumption miles later it was wiped out when some idiot made a left turn across 5 lanes of traffic on a 6 lane highway. No one hurt.
One good point about that TBI car is that it consistently got 28 MPG at a highway cruise. Pretty decent when a lot of 4 and 6 bangers won’t even get that.
My shop truck is an old GMC with a 454 and a TBI. Never had any major issues with. Good gas mileage for a 1 ton dually as well. No compalints there. Nice thing about is that I don’t think it has a body computer, so no external garbage to fail like on stuff now.
[quote=”andrewbutton442″ post=125106]My shop truck is an old GMC with a 454 and a TBI. Never had any major issues with. Good gas mileage for a 1 ton dually as well. No compalints there. Nice thing about is that I don’t think it has a body computer, so no external garbage to fail like on stuff now.[/quote] A BCM in any vehicle is totally unnecessary in my opinion.
You know, I agree with you. I actually got into a discussion with a tech who has to fix all this late model stuff..and his answer was this.. you wouldn’t even be able have things like Rain sensor wipers without body computers. I really didn’t know what to say, other than, well, it controls a bunch of unneccessary things then….sorta like having a toilet with rhinestones… BCMs and the likes are meant to shut the indenpendants out and keep Stealerships in business…. count me out of that scam.
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