PabloCruise
SILVER Star
DPV7070 said:
Awesome!
Looking forward to a good read!
Would there be any interest in an UNBIASED carb shootout? (1 Viewer)
- Thread starter msapers
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Awesome!
Looking forward to a good read!
- Thread starter
- #42
Ok, that makes sense. I'll include this info too.
- Thread starter
- #43
Indeed. I plan to include all the variables for each carb as applicable, (jets, emulsifiers, power valves, accelerator pump cams, metering rods, etc..) I'd be interested in any recommendations you have on optimization of the stock F/2F carbs.
- Thread starter
- #44
Guys, keep in mind that it's just me. I don't have access to a dyno or a staff of test pilots!
The point of these specific tests is to determine which carb performs best under measureable, real-world circumstances.I should probably mention that I do not have a "favorite" in this test. I really don't know which carb will come out on top. My feeling is that different carbs will excel in different circumstances and people will be able to look at this data and choose which carb best suits their particular needs.
The genesis for this idea came from reading this board almost daily for many years and seeing the responses to new guys asking how to tune their Holley, Weber, Rochester, etc. Invariably, the response is "Junk it and go back to stock because Webers are untuneable, Holleys flood out if you go over a speed bump, Rochesters are doorstops, etc. Maybe they're right, but maybe they're wrong. I'm an "I want to see it for myself" kind of guy.
I've had great success running Holley and Rochester 4 bbl carbs on V8 4x4 trucks for years. I have never run the 2bbl versions on a Toyota six, but the principles are the same.
I will be as fair and objective as possible. I'm open to a volunteer observer to keep me honest if anyone feels it's neccessary. Must be willing to work for quesadillas and beer.
PabloCruise
SILVER Star
Yep, sounds like a food volunteer effort and also sounds like you will be keeping track of a lot of variables!
I look forward to following your posts!
One small request: after the carb comparisons, would you mind dropping in a 3FE and letting us know how that compares in your vehicles?
I look forward to following your posts!
One small request: after the carb comparisons, would you mind dropping in a 3FE and letting us know how that compares in your vehicles?
- Thread starter
- #46
I should also mention that in my opinion, it's unlikely that any one carburetor will win in every category. The beuty of this test is that people can reference it to see which carb was best in the type of driving that they do.
Here's how I THINK it will shake out:
The Weber will make the most power with the worst mpg.
The Holley will make more power than stock with slightly better MPG.
The Rochester and Motorcraft will be the same as the Holley.
The Trollhole carb is a wildcard, as I have no experience with them.
The stock carb will make the least power with middle of the field MPG, but best overall driveability.
Those are just opinions though. We've already got plenty of opinions here. I could be very wrong. I really want to give each of these carbs a chance to shine, so please feel free to share any tuning tips and tricks that you have. This test will only work if each carb is setup to be the best that it can possibly be.
Here's how I THINK it will shake out:
The Weber will make the most power with the worst mpg.
The Holley will make more power than stock with slightly better MPG.
The Rochester and Motorcraft will be the same as the Holley.
The Trollhole carb is a wildcard, as I have no experience with them.
The stock carb will make the least power with middle of the field MPG, but best overall driveability.
Those are just opinions though. We've already got plenty of opinions here. I could be very wrong. I really want to give each of these carbs a chance to shine, so please feel free to share any tuning tips and tricks that you have. This test will only work if each carb is setup to be the best that it can possibly be.
- Thread starter
- #47
One small request: after the carb comparisons, would you mind dropping in a 3FE and letting us know how that compares in your vehicles?
Sure, why not?
So would about 10,000 of us.
If we could only get Jim and Mark to let us in on all of their secrets! Great project. Thank you for the service you are providing for the 2F community. JD
So would about 10,000 of us.
Heck, I'd settle for 10% of their secrets.
JohnnyC
Long ago TLCA# 2231
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
My prediction is that other than running at a steep incline, it will be hard to see any significant difference in the carbs. It isn't easy to be sure any difference is true and significant and not just due to random variation without statistical analysis. It is much more work to make sure that any difference is statistically significant, so it would not be worth the effort in my view.
how about if he repeated the test for each combo on three different days
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.
Subscribed Can't decide on rebuilding my OEM 78 carb or going with a Trollhole carb. Leaning to Trolls.
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
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
Last edited:
77mustard40
SILVER Star
Pin_Head said:
Having just spending my first day on rocky steeps and off camber climbs and descents with an Aisin (after many years with both a Holley and a Weber) I will say that I was very pleased with the stock carb and that's with a manifold vacuum leak to boot. I found that I had full control of the motor when it was most needed and I'm not used to that. One day doesn't make an answer, but I have 26 years split between the other two in the same vehicle and I had more confidence with stock within minutes when the going got tough.
I'm interested in the study but doubt it will influence me away from the Aisin.
X2, to be honest.
My experiences with the Rochester 2-Jet and the Weber 32/36 were fairly positive but I love my rebuilt Aisan. Great fuel economy; good performance; and having the original pedal and linkage, and insulator, and hard fuel lines, and air filter housing all together again just feels inexplicably good.
I am very interested in seeing the results, but I think the only thing that would make me give up the Aisan is a 3B.
PabloCruise
SILVER Star
ToyCO said:
I'll take your old '78 if you are going to get rid of it?
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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...
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...
