Would there be any interest in an UNBIASED carb shootout? (1 Viewer)

[msapers]

how about if he repeated the test for each combo on three different days

That's doable.

 

[msapers]

they obviously don't know webers with that comment...weber are very easy...they just don't know them

most euro cars are converted to them because of their low maitnance and tuneability per application...most webers are techincally sold here as one size fits all (speaking of the jetting) but just as any carb it needs to be jetted correctly

Exactly. This will only be a fair test if each of the carbs is tuned properly.

 

[msapers]

This sounds like a great project. It will take a lot of time and tracking but I say go for it. I am up in Fresno so if I can help just let me know.

Will do, thank you!

 

[msapers]

What is your elevation?

seems like you may need a supply of various jets to get the job done.

I use a buddy's innovate lm2 wideband o2 sensor to read Air fuel ratio's/.
LM-2 Wideband O2 Digital Air/fuel Ratio Meter

I'm at sea level here in Los Angeles. For the higher altitude portion, I plan to go to Big Bear which is around 8000 feet. I know it's not comparable to those of you that live high in the Colorado rockies, but it's the best that I can do. I'll include GPS altitude readings for each portion of the tests.

I don't have the funds for an O2 meter.

 

[msapers]

An ubiased carb shootout? Did that about 20 years ago.
Here's some dimensional data (as opposed to statistically insignificant opinions) from an old post:

The Holley is a little larger CFM (350 vs 300) than the weber 38/38, therefore more power potential, if it is ever tuned to operate correctly with the engine. I think the holley is more reliable than the weber because it has a much more reliable adapter thingey. The fuel economy is pretty bad with either carb because they are shipped w/ fat jets and have unnecessarily large accel pump capacity. Off road, they are both pretty bad as shipped, but both can be tuned and tricked to work better.

That being said, the stock Aisan 38/40 spanks them both.
Power: Aisan is 425 CFM, plenty of capacity for a 4.2 or 4.3L engine.
Reliability: Aisan is very reliable for two reasons.
One, it is designed to be reliable. Not designed to be cheap to produce and fit any engine.
Second, it fits the vehicle with no troublesome manifold adaptors, cheapo open element air cleaner, rigged bicycle throttle cable or other half-#ssed coversion parts.
Economy: carb is the right size for the engine, has economical vacuum secondary design.
Off-road: it is designed for Land Cruiser off road use.

There are some folks who report that the (insert cheap aftermarket carb name here) carb worked wonders on their truck, improving starting, power and fuel economy. They went from 10 MPG to 15. That doesn't mean the (insert cheap aftermarket carb name here) carb is better than a properly set up Aisan, it just means that the original carb they had was not operating correctly. My own DD FJ60 gets 16.5MPG at a steady 100KPH, which is pretty good for a '60 w/ stock exhaust.

More from another thread:
Stock FJ60 carb is almost the biggest that is readily available. 75-76 USA carb is biggest CFM available, around 425.

The weber 38/38 that is commonly sold as an upgrade has 38/38 throttles and 26/26 venturis.

By comparison Aisan 38/40 has 31/35 venturis.

Aisan throttle area: 23.90cm^2
Weber throttle area: 22.68cm^2
Aisan is 5% bigger.

The limiting factor to airflow through a carb has to be the venturi. For the carb to work right, there must be a significant delta P right at the venturi, a greater change than anywhere else in the induction system.

Cross sectional flow area at the venturi:
Aisan: 17.17cm^2
Weber: 10.62cm^2
Aisan has 61% more CSA in the critical venturi area.

I'll stop carrying on now. I hear the attendant is bringing my meds...

I don't think CFM will be the deciding factor at the RPM that these engines see in regular driving. Rather, I believe that the percieved power increase of the aftermarket carbs is due to both barrels opening simultaneously instead of the stock primary/secondary setup.

I agree that comparing a worn and improperly adjusted Asain to a new Weber/Holley/Rochester/Motorcraft carb is pointless and will not produce any useful data. Trollhole has graciously offered to provide a carb for testing as well as tech support that should give the Asain carb it's fair shot.

Whether a carb was "designed for the Land Cruiser" or not is, in my opinion, not at all relevant to non-purists. I (and many others), want to run the best carb possible on my Land Cruiser for the type of driving that I do. If this turns out to be the Asain, then so much the better. but if it turns out to be the Holley, Weber, Motorcraft, or the Rochester, you'd better believe that that's the carb I'll run.

I'm not a Cruiser god like you, Mark, and Trollhole. I'm just an EMT who works weird hours, has a couple of Cruisers, some tools and a few carbs. I will be happy to take suggestions from anyone on how to make this test as valuable as possible.

I certainly don't mean anyone any disrespect. I do not doubt your experience and you may very well be right about stock being best. Perhaps I'm doing nothing more than wasting my time. But when I'm through wasting my time, I will know for myself what's best rather than having to base my decision on someone else's subjective opinion or what others have heard from their cousin's brother-in-law's former roomate's 2nd grade teacher who knew a guy that used to live next to somebody that had a ______carb on his 'Cruiser.

 

['69 Yota]

Any updates on this?

 

[Trollhole]

Yeah. It wasn't going to be unbiased. Look at his sig. That being said I was looking forward to someone doing this. But to be honest I really don't think you could ever find someone who isn't going to be unbiased and be able to keep the tests consistent. I think the best carb shootout has already been done. In the hundreds of post done on mud already.

 

['69 Yota]

Yeah. It wasn't going to be unbiased. Look at his sig. That being said I was looking forward to someone doing this. But to be honest I really don't think you could ever find someone who isn't going to be unbiased and be able to keep the tests consistent. I think the best carb shootout has already been done. In the hundreds of post done on mud already.

I just watched that little vid this morning. I thought it was humorous, but definitely takes the "un" out of unbiased. Do you have any carbs available?

 

[Mark W]

Can't say that i see much point in this "comparison".

At first glance it seems like a fun project that might provide meaningful info... but looking closer:

The premise that "these represent what most of us are driving" is a stretch right at the start. I doubt that stockish FJ40s on smallish tires represent the majority of F series powered Cruisers out there. If you accept that, then there is the question of how the engines themselves are set up and tuned... as well as overall condition of the engines and any ancillary systems that can affect performance.
There is also the considerations of what non-engine mods have been done to the rigs, what type of driving will be done... what type of terrain... what sort of driving style, vehicle load, temperature, altitude and who knows how many other variables that will not be applicable to all of the other people driving Cruisers in different places under different conditions with different needs.

Then there is the question of the condition and tuning of each carb.... there was mention of picking up a motorcraft from the junkyard???. All units new out of the box, or tuned by an expert in each model of carb would be a lot more likely to eliminate a LOT of uncontrollable variables.

Now if you were to conduct this test with the aim and the claim to determine which of the individual carbs that you use on your vehicle worked the best for your uses under your conditions... then that would be a bit more meaningful, and would provide a relevant data point for those considering and comparing carbs... but not really any more so than the reported info and opinions that are already floating around here and other places based on others experiences.

No reason not to do it. but be cautious about reading too much into the results.


Mark...

 

[lcwizard]

I've always felt my favorite carb was the one in a box on the shelf after it had been replaced with injection

 

[Mark W]

I've always felt my favorite carb was the one in a box on the shelf after it had been replaced with injection

^^ ditto.

In my world one of the biggest pluses of injection over carbs is that EFI will take a little water and keep running. I have been amazed at the quantity of water that an EFI system will eat and keep running. Where as it only takes a few drops to put a stop to carburetor action. An injected engine may not run great as it runs through some contamination, but at least I am not tearing it down on the trail to clean and drain. And if you do get more water in an EFI system than it can handle, it is still just a matter of draining and purging. you do not have to disassemble to wipe and dry by hand.

Between water that finds its way in through the intake tract, and water that finds it's way into the tank somehow, water from 55 gallon drums cached out in the back country for weeks, water from who knows where, this is always a consideration for us.


Mark...