Mixture and Idle adjustment for Weber 38 Carb (1 Viewer)

[FZJ80ismybaby]

Hey y'all, looking for some answers here. titled it to help others in the future searching for this material..

i dont know what to do with the weber. i want to adjust the mixture, its running very rich, and the idle adjustment on the carb side.

Q: does it have an idle adjustment screw?

Q: How do you adjust the choke at idle, and does it ever stick open like in the pic below?

Q: How do you adjust the Mixture?

this picture is at idle? stuck?

 

[JohnnyC]

Q: does it have an idle adjustment screw?
A: the idle screw is on the throttle linkage side...the linkage rests on it

Q: How do you adjust the choke at idle, and does it ever stick open like in the pic below?

A: it looks like that when its warm and at idle

Q: How do you adjust the Mixture?

A: the mixture is adjusted on the valve cover side as well as the fender side of the carb

this picture is at idle? stuck?

A: looks like its all warmed up and ready to go

do you know what size jets you have in there?

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

 

[65swb45]

Just because it's a Weber,...

and just because it's a 38mm Weber, which is NOTORIOUS for running rich...

and just because your TRUCK is running rich...

doesn't necessarily mean it's a carburetor issue. A weak spark will cause a truck to run rich as well. What dizzy are you running? If it's a points-type, what's your dwell and static timing?

I don't like assuming things.

Best

Mark A.

 

[FZJ80ismybaby]

H E I dizzy, gaps and timing set correctly. i apologize for not mentioning all this. the valve timing was all set as well.

i dont however know the jet size.. where can i find info on that? i've looked in the manual, but its all jibberish to me.

 

[FZJ80ismybaby]

i was doing a little test drive today, up to a certain RPM. it tops out and doesnt stop accelerating, but there is sudden power loss.

i wish i had a tach so i could know where exactly it tops out at. by the sound i'm going to guess 3,500 or 4,000 revs

 

[SUMMIT CRUISERS]

I had a similar situation on a weber a few years back. I contacted Reline Weber and they helped with jet size and I purchased a rejet kit from them (about 60 bucks). It runs much better and not as rich. If you go this route, you need to remove and disassemble the carb to get the jets sizes and then give them a call.

 

[FZJ80ismybaby]

i read somewhere on another thread it could possibly be the accelerator pump.... any insight on that?

 

[65swb45]

i was doing a little test drive today, up to a certain RPM. it tops out and doesnt stop accelerating, but there is sudden power loss.

i wish i had a tach so i could know where exactly it tops out at. by the sound i'm going to guess 3,500 or 4,000 revs

So, it could be runing rich at lower RPMs AND lean at the upper end. That is ONE of the reasons why it is preferable to have a carb where the barrels open individually: you can adjust jetting across a broader powerband than you can with one where the barrels open together.

Best

Mark A.

 

[FZJ80ismybaby]

hey mark, i actually had a notion today and i had thought about that possibility, wonder what to do with the 38 to fix it... hmmm

 

[JohnnyC]

have you adjusted the idle mixture screws? had you gone thru and adjusted the carb to see if the idle jets are not too big?

 

[FZJ80ismybaby]

thats a big negative good buddy, i looked in the manual but it wasnt much help

 

[FZJ80ismybaby]

im thinking that taking it to a specialist might be the best way to do this

 

[fj404life]

Id put a Toyota Carb on there before you pay someone else to futz with your Weber. Youll probably save $$ if you shop around.

 

[FZJ80ismybaby]

i was contemplating it