Carb mod for better mileage?
 

Was trying to find the post by someone with an '82 Toyota 4x4 that had mpg issues....

"....also lower your floats to the lowest point possible without starving engine for fuel 1/4 to 3/8 of normal hight is a good start....carb manufacturers run 'just below flooding' fuel levels.

Try lowering your float in the carb to about 1/2 inch, as long as you don't keep your foot buried in the throttle you will see a major increse in MPG, my 73 f-100 (360 auto) went from grandma 6mpg to 2000
pound past capasity of 12.5 trip average from Washington state to Texas (2400 miles) and the truck burns(& leaks) 3 quarts of oil every 100 miles.

Your only limit is the floats hitting the bottom of the bowl. You may think 'The bowl will run out of fuel' if your that hard on the petal your not in the habit of getting good mpg anyway. Just use reason give your floats room to open the needle valve but not fill the bowl all the way up. The reason you get better mpg is greater levels of suction are needed to pull the fuel up the stem 'ripping' the fuel apart on the way up the high speed nozzle for more air contact (surface area)."

Is your Turkey carb'd? Maybe you could try it out?

tercel will take a weber...

...but that float level stuff..keep it as high as it will go. for every bottom out there is a lack of stoich, and it will dump it trying to gain it back. The goal is "float". :confused:

never ever drop the float.... EVER. :thumbup:

Moi...does not drive a Turkey...but a POS. :cool:

I am going to try this soon...since I need to take stuff off to fix a coolant leak....where I'll be installing a 192F thermostat. Will also put in a new float/valve while I'm at it.

If you read what he says...your limit is the float bottoming. This carb has a sight glass in front...last I looked the level ran slightly below the line...so it might not adjust any further down. Doubt if it's going to "dump" fuel at any point...if adjusted too low you simply won't get enough fuel because the valve won't open enough.

Not afraid to try it...just don't want to be taking the top off the carb when I can avoid it...which is why my carb rebuild kit has set in it's box for a few years.

i think i need pics. to see what you're doing.
i was messing with my carb before the cold weather set-in.

Took a look at the manual...says not to mess with the center tab that actually actuates the valve...says that this carb is set up for strict emissions....and since by the sight glass it runs a little low already...I might not mess with it.

I'd probably end up having it off there several times before it ran right again.

Changing the float level might more likely work on US carbs on the bigger engines?

LaPointe mentions soldering the power valve shut.

I've rebuilt carbs before...but it can be hit or miss at times.

By all means, do whatever La Pointy says!!!

I've brazed the power valve on quite a few carbs... on older 4 cylinder cars, it really doesn't affect anything unless you intend on floor it and go - type fuel delivery.

Several Kei-Hin carbs were known for their ability to randomly flood engines when you hit the gas too heavy, too quickly. The fix is to close the accelerator jets off, and use the throttle at bit more sparingly (or listen to a backfire every time you hit the pedal too quick).

The only way that you can run lean by moving the float in the bowl is if the bowl starts to get empty. I find it highly unlikely that you'd get better fuel economy by doing it, considering that no matter how many times I've adjusted the floats on any of my industrial engine carbs, they still run for the same amount of time on the gallon fuel tank they have.

Of course, they're steady state engines, too. Maybe something's different there.

When anyone is ready to get serious about adjusting the mixture leaner, they'll rejet it.

I thought this to myself, but didn't mention it, because "Frank-Lee", if you're not willing to take the carb apart to put a few gaskets in it, you're probably not going to be interested in re-jetting it, either.

Me, on the other hand, I'd be the one trying to make my own jets on a lathe. :)

Right on! Too many times (for too long) I have heard / seen people fiddle with the idle mixture screw(s) and expect miracles. The high speed jetting is built into the jets; don't think of drilling 'em out bigger, either. You'll only mess up the smooth bores.
Plugging the power valve(s) force the jet(s) to carry the full fuel load; power valves are a controlled leak....
Oh! One more "point": LaPoint isn't God. He & I have gone 'round & 'round before ... I'm not sure where he learned his flame front terms, but when it comes to gasoline chemistry, he is "old school". Pump gas is garbage. Not the same as yesteryear. There is wiggle room here, too. Lots.

...Chrysler and Honda learned a "lot" about LEAN-BURN techiques...both electronic and mechanical.

Have y'all tried the 'Carburetor Enhancer' from Eagle-Research? I heard it works...

I've heard of the carb enhancer...but will be testing a FA2000 clone this summer.

This is basically an gas supply teed from after the fuel pump, that is run thru a sensitive valve so that just a trickle is allowed to get into a 3 foot long extended part of the PCV circuit...causing an amount of fuel vapor to be fed into the engine.

Along with adjusting the slight fuel flow thru this valve...they recommend adjusting the float level using this method:

* adjust the float level 1/16" lower...then take the car out on the highway at 60-65 mph and step on the pedal...if it bogs down...it is adjusted too low...if not...drop it another 1/16". Keep doing this till it bogs. Then with the TC2000...you are supposed to be able to turn it on and the "bog" effect will go away.

This same method could be used without the TC2000...adjust till it is CLOSE to bogging down.

is bogging the same as chugging?
i have an auto transmission. i have yet to look for my float.

Can't wait to see the result...

what's a TC200?

Got that wrong...FA2000...they don't sell them anymore...you could easily make the equiv for not too much.

http://www.nonags.org/members/nijqk/FA2000.jpg

Had a recent tank come in at 36 mpg...which is a good gain...but this was mostly before the FA2000 was operational...seemed like a legit fill...but hard to say due to ahole issues...aholes that interfere with a fuel refill.

What are aholes? I can think of one meaning but i don;t think it pertains to this thread. Did you notice a difference with the fa2000?

Fuel is not sucked up the jet nozzle,it is pushed by the atmospheric pressure above the fuel level in the float bowl.By lowering the fuel level you have reduced the volume and wieght of the fuel which is being acted on by the atmospheric pressure.So you have leaned out the a/f.Same affect as reducing the jet size or reducing the atmospheric pressure.

You don't have to take the carb apart to lean it out under high manifold vacuum conditions.You can just run an adjustable manifold vacuum source to the float bowl vent and regulate the amount of atmospheric pressure in the bowl with the amount of vacuum you administer.

Sounds like the "carb enhancer" to me.

Put a vac source on this tube...run the looped line inside to a sensitive needle valve...adjust the float bowl pressure manually from inside as you drive?

Here is my ahole story....

Maybe 10 yrs or so ago (in winter)....I was parked along a road in some woods taking a break when a couple of guys came along in a pickup nodding and smiling. A couple minutes later they come by again...this time lookin' mean. I think...hmmm...and head home.

Got maybe 50 miles or so to the NW and stopped at a gas station to refill...but the pump didn't shut off...spilling maybe a quart of gas on the ground. It was enough that I was afraid to start the car up...so I pushed it away from the pump and went inside...asking the Middle Eastern type guy at the counter WTF...he said that 2 guys did it...sitting nearby looked like the same pickup...probably driven by 2 aholes.

So what were the aholes up to? Probably some kind of ahole test to see if I was paying attention....there is a sign on the pumps saying that you are responsible for the pump shutting off. No matter if there is a fire at the pumps and people get burned...the aholes wouldn't know anything about that. If there was a fire...you'd just read in the paper about some irresponsible driver who caused the fire....aholes can do no wrong.

They can also cause the pump to run slow.

Can't say why I got the 36 mpg...unless the aholes have found a way to give me some free gas. :thumbup: The car was definitely full....previous tank was avg.

As far as the FA2000...testing will be slow...but I do intend to do a thorough test if possible....things been sitting in a box for 5 yrs or so.

subaru was there too...pulling more than a honda and outlasting the chrysler.


There is other means to gain lean burn, outside air has to be correct. The winter mode on my carbed sube went away today, it needs nearly 80 degrees to click out of it (audibly so). Now in 40s mpg mode, in the winter, it loses ten mpg...(6 months for me)
I do not know what does it, but do know what I had to keep hooked up for it to function. My carb is not in the books, it took a small boost (a blo through hitachi).

if the plans worked in america for feedback, we would not be killing ourselves over the retards that could not make it work. *cough*holley*cough*

I mean 175 billion gallons of gas a year with not nearly enough more cars on the road to justify a doubling in consumption kills all arguments about injections winning. Good luck with your carbs, they are the winner. :thumbup:

I am pondering a 32/34 weber next, it is not a master, but I can preserve the genius I am running now if I swap.(I am restoring)


progressive 2 brrl, feedback, thermal monitoring of vacuum actuation.. it is a genius. No ECU necessary.

BGD - Also keep in mind that most people drive more now than they used to. So, even with the same cars on the road, fuel consumption would be higher.