Weber Carb

[Joseph Siri]

I have seen the thread about webers here in tech, but, i dont see anywhere about making them have better fuel economy.

I am not planing on going to the oem carb, i just dont have the money for that.

My truck is a 1972 fj40

I am getting about 10 mpg with the weber 38dgas.

the Idle jet is at 50 AFAIK

the mains are at 150 and air correction is at 190.

I had an fj40 (also a 72) before this one, also with a weber 38dgas and i was getting about 14 mpg, th the same tire setup also 33" BFG's.

which would effect economy more the mains or idle?

i know the idle effects the lower RPM range...and the mains the upper from 1/3 throttle onward?

 

[SouthBostonFJ40]

Is your goal to get better than 10 MPG?

 

[Joseph Siri]

Is your goal to get better than 10 MPG?

would be nice to get 14 again.

I dont know what jets were in the 1st 38 i had.

do you know if there is anybody here really good with webers?

 

[kissmyaxle]

I will try and find the post I read about 2 weeks ago and post it for you about the weber jet tuning/ replacement. BTW, I talked to a specialist working for weber and he said the jet replacement theory is bogus....i dont know, just what he said. standby/.

 

[FJ40Jim]

I will try and find the post I read about 2 weeks ago and post it for you about the weber jet tuning/ replacement. BTW, I talked to a specialist working for weber and he said the jet replacement theory is bogus....i dont know, just what he said. standby/.

What is "the jet replacement theory"?

 

[kissmyaxle]

Not exactly what I saw but maybe will help on the settings. I will keep looking for you though.

Webers generally come with 155 mains, 60 idle, and 180 air correction, and is said to be correct for sea level.


Here is a thread where treeroot and I were trouble shooting the Weber dilemma

38/38 Weber on an F/2F - Pirate4x4.Com Bulletin Board

I think my final set up was 135 mains 45 idle and 180 or 190 air correction
I remember that my set up in that thread was a little lean

If you wheel make sure you lower the float bowl, the webers can run very well on a wheeling truck if you tune them right


__________________
FJ-40 on FO-DEEs
just a lil guy
HOMEGROWN

Jim as far as the "Theory" the guy told me about, He said...nutshelling here....The webers come with proper jets already installed. The only time you would need to adjust the jets would be due to elevation of where you live. Reason I was asking started with my weber not performing at peak. I was thinking of rejetting mine when he brought out the song and dance of "thats what everybody does and I dont know why they do that because it just adds to existing issues, and does nothing but hurt fuel economy and performance. Three things that need fine tuning for peak performance are air/fuel, choke, and idle." The guy deals exclusively with JTO. Called them about this choke problem I had and they sent me to him. I figure the guy knows, but everyone has an opinion about these sort of things.

 

[grant5127]

I had an fj40 (also a 72) before this one, also with a weber 38dgas and i was getting about 14 mpg, th the same tire setup also 33" BFG's.

It's possible the the over all health of the second cruiser engine is not as good as the first... have you given the engine in question a physical??

 

[kissmyaxle]

this is interesting as well. 4th page.

Jetting and Tuning Downdraft and Sidedraft Weber Carbs. An Overview and Short Course:

 

[Joseph Siri]

I think this is the thread that you are refering to?

https://forum.ih8mud.com/40-55-series-tech/213147-***weber-carb***-adjustment-thread.html

GREAT Information, I will need to look into some things

 

[Joseph Siri]

It's possible the the over all health of the second cruiser engine is not as good as the first... have you given the engine in question a physical??

My new rig has better compression and less miles.

Thats why i'm alil perplexed why i'm not getting as good of a MPG.

Runs like a champ otherwise.

 

[kissmyaxle]

Yep, thats the one. Good luck and hope that helps.

 

[bustanutley]

Remember that treeroot and I are at a mile high

 

[lehiguy]

I sent you a PM. I can almost gaurantee that your idle jets are going to need to be replaced with leaner ones, and possibly the mains as well, but I need to know where you live and a few other things too.

 

[AKcruiserfreak]

I'll have to check what jets I have in mine, but I get 15-16mpg with 33" tires at 400' above sea level.

TK

 

[Joseph Siri]

I am at sea level.

I was thinking when i first noticed the bad fuel economy I should tune it up. I replaced cap, rotor, NGK plugs, wires, and cleaned the K&N, cleaned the PCV, its got petronix ign.

There are no vacuum leaks anywhere carb/intake all checked out ok.

My timing is at 12 deg.

thanks in advance

would be cool to hear what sizes you guys have. My next step is to do a rebuild. I would like to order the correct jets.

a question I have is how do I remove the idle jet? the air and main are easy

 

[Joseph Siri]

ttt

a question I have is how do I remove the idle jet?