Why everyone carb swapping?

[L31MaxExpress]

And therein lies the rub. Tune your carb to run good at your present elevation and it all goes to ***** when you go up a mountain or down to sea level. Down here the highest elevation is about 90' above sea level,but if I were to go to someplace like, say Denver with my sea level tune I'd be fuel fouling plugs.

I went over 12,000 ft this past spring in Colorado in the Pathfinder with its factory EFI and it cared less. I saw an older IDI era Ford diesel trying to get a smaller trailer rolling at altitude and it was a smoke show just like a carburetor would be. In the thin air it was down on power but it also managed the best mileage I have ever seen it get climbing out of Denver on my way to Pagosa Springs across the high plains. My brother in law was in his 2019 Duramax 2500 and it ran well at altitude too. EFI for the win in both cases.

 

[Supercharged111]

I went over 12,000 ft this past spring in Colorado in the Pathfinder with its factory EFI and it cared less. I saw an older IDI era Ford diesel trying to get a smaller trailer rolling at altitude and it was a smoke show just like a carburetor would be. In the thin air it was down on power but it also managed the best mileage I have ever seen it get climbing out of Denver on my way to Pagosa Springs across the high plains. My brother in law was in his 2019 Duramax 2500 and it ran well at altitude too. EFI for the win in both cases.

And IDI Ford FTL in any case.

 

[L31MaxExpress]

And IDI Ford FTL in any case.

My uncle owned one years ago here at ~600 ft elevation and had to max out the fuel adjustment just to pull a fairly light trailer with any kind of reasonable power. His was a non turbo 7.3L as well not even the 6.9L DOG.

 

[Schurkey]

Some (early) Thermoquads were "solid fuel" carburetors. In this case, "solid" fuel meant "no air bleeds".

Must not have worked out very well, I guess the later Thermoquads had at least some air bleeds.

Single biggest problems with Thermoquads were the screws that folks didn't see when trying to take them apart, so when the prybar came out the plastic center-section was destroyed; and the expensive and fancy rubber "X" rings that would get replaced with common "O" rings from cheap rebuild kits.

 

[L31MaxExpress]

Some (early) Thermoquads were "solid fuel" carburetors. In this case, "solid" fuel meant "no air bleeds".

Must not have worked out very well, I guess the later Thermoquads had at least some air bleeds.

Single biggest problems with Thermoquads were the screws that folks didn't see when trying to take them apart, so when the prybar came out the plastic center-section was destroyed; and the expensive and fancy rubber "X" rings that would get replaced with common "O" rings from cheap rebuild kits.

I still like the Q-Jet design, especially the later Mod Quads a lot better. After ~1975 they were modified by GM, got the 3rd fuel bowl screw up front, the externally adjustable APT and the larger fuel inlet nut. Much better design than the earlier ones. I have never seen the welch plugs leak on the later model ones either and I have probably built 100 of the Q-Jets and DualJets using the later style castings. I had a strong dislike for the electronic ones but that was mostly because owners and prior shops had hacked up the systems so badly that they would not run right without a lot of work putting things back like they should have been.

 

[TonyM]

The only reason people carb swap is lack of computer tuning knowledge and skill. Besides being easier to "tune", there is no advantage at all to running a carb over a proper efi set up for the application. None.

What I meant was, there is no efficiency or reliability advantage to running a carb over computer controlled efi. An ecu can make thousands of decisions a second to keep an engine running smoother/cleaner/efficiently. Can a carb make more power on a drag car (which is irrelevant here cause 99% of us don't have a drag car), possibly. Can a carb make more power on a street vehicle, not if the efi system is built, set up and tuned right.

There's a reason why you can't buy a vehicle built in the last 20-30 years that has a carb. Even honda quads are finally getting away from carbs lol

 

[L31MaxExpress]

What I meant was, there is no efficiency or reliability advantage to running a carb over computer controlled efi. An ecu can make thousands of decisions a second to keep an engine running smoother/cleaner/efficiently. Can a carb make more power on a drag car (which is irrelevant here cause 99% of us don't have a drag car), possibly. Can a carb make more power on a street vehicle, not if the efi system is built, set up and tuned right.

There's a reason why you can't buy a vehicle built in the last 20-30 years that has a carb. Even honda quads are finally getting away from carbs lol

Even small engines are getting away from carbs. Generators especially are now coming with EFI on them. Small engine + carb + ethanol = trouble.

The old flathead briggs on my rotortiller is getting tired and I am actually considering putting a Yanmar diesel clone on it. I briefly looked at and considered a new tiller, the newer ones are thinly constructed lightweight JUNK that cost 2-3x what they should. Even if that Yanmar clone only last 3-4 years it would be worth it. The diesel would rectify several problems at once. The fresh engine, the storage issue with ethanol fuel, and would likely generate some additional soil turning low speed torque compared to the 5 hp briggs I bet a 3.5 hp Yanmar clone would work just as effectively.

 

[Scooterwrench]

What I meant was, there is no efficiency or reliability advantage to running a carb over computer controlled efi. An ecu can make thousands of decisions a second to keep an engine running smoother/cleaner/efficiently. Can a carb make more power on a street vehicle, not if the efi system is built, set up and tuned right.

Oh contrare Mon Capiton. A well setup Q-jet can run circles around EFI and get very good efficiency and economy on a street vehicle. What it can't do is automatically adjust for barometric pressure,it's only downfall. If they were only race carbs Detroit wouldn't have put them on just about every V-8 that rolled off the line.

There's a reason why you can't buy a vehicle built in the last 20-30 years that has a carb.

That was the EPA's doing,not the auto makers. It's the EPA that is forcing fuel injection on small engines. It costs a lot of money the design and manufacture parts for EFI and your the one having to pay for it.

 

[L31MaxExpress]

Oh contrare Mon Capiton. A well setup Q-jet can run circles around EFI and get very good efficiency and economy on a street vehicle. What it can't do is automatically adjust for barometric pressure,it's only downfall. If they were only race carbs Detroit wouldn't have put them on just about every V-8 that rolled off the line.

That was the EPA's doing,not the auto makers. It's the EPA that is forcing fuel injection on small engines. It costs a lot of money the design and manufacture parts for EFI and your the one having to pay for it.

Q-Jet runs good, but it is definitely not running circles around EFI. I have a dual plane MPFI manifold with a 1,000 cfm throttle body on it. It would give a Q-Jet a run for its money for peak power and likely win out on average torque and a 1/4 mile run. Just controlling the ignition timing via computer can add a good bit of torque throughout the curve. That is ignoring the EFIs fueling advantage of being able to optimize the AFR in every cylinder. Another big advantage at idle and low loads is being able to delay the injection of fuel until the exhaust valve is either closed or close to closed on split overlap. This greatly reduces the amount of fuel wasted that would otherwise be pulled into the exhaust.

 

[PlayingWithTBI]

I don't think any carbed engine could pass Commiefornicate's emissions standards for HC and NOx and still beat an EFI in every day driving.