Weber carb adjustment questions (1 Viewer)

[offcamber40]

Is there a service manual out there specifically for Webers? Ive got my cruiser's timing dialed in to where it seems pretty good, and the idle mixture settings to where they seem good as well. I have no vacuum leaks, but I am still getting a flat spot/miss midway through the rpm band. If I depress the gas really hard It almost dies.. When the car is cold and the elctric choke is activated, I can rev it all day with no miss whatsoever.. is there a high speed circuit adjustment that I am missing somewhere? I know the idle mixture screws control the low speed circuit. My MAF instructions are useless..

Mike

 

[Poser]

Here ya go!

http://www.webercarburetors.com/

 

[Poser]

Assuming that this is a 38...

http://www.webercarburetors.com/ppw/html/tech/38_dgas_tunning.htm

 

[offcamber40]

Thanks Poser, it looks like I may need to re-jet this thing.

Mike

 

[toddslater]

There is a weber book..bible if you will that will assist in tuning your weber. When I return home I'll post that for you. I looked at the 38 post that poser sent...that is merely choosing the correct idle jetting. Your problem does not appear to be idle jet related. You may get by by increasing jet size and unfortunately I don't know off the top of my head what exactly the 38 has progression-wise from the loe speed to high speed circuits. I'll look at it when I return on Friday.

 

[Poser]

I would be very interested in seeing this info also.

Thanks!

-Steve

 

[toddslater]

I'm back and tired...my weber book is an old haynes book on webers circa 1979. It does cover the 38 dgas carbs if that is indeed what you have. Based on your description above, I would think it would either be an issue with the accelerator pump or the main jets. Seeing as it appears to operate normally when cold/full choke...it may be main jets are to small. The accelerator pump operation is easy enough to check...look down the barrels and see if you get a spray when you open up the throttle. If that spray is fine then I'd look at increasing the main jet size. One last thought...I might be inclined to put an inline fuel pressure gauge in between the fuel pressure reg and carb inlet to ensure 2.5 to 3 psi during operating conditions. If you want I can also fax you pages from the book for your use....that would be on Monday though.

 

[73lndcrsr]

I have seen the Weber Haynes book at several parts stores lately. It will walk you through the rebuild process, but jetting is another story. How do your plugs look? Can you drive it at all?

If you can drive it some you will be better informed about how rich or lean it is. If you are in the driveway you will never be able to get a load on the carb. You will be on the idle jets most of the time.

A mile or so will give you a decent picture of how the carb is performing. DRive it and check the color of your plugs.

 

[Hugh Heifer]

Bump - proof the search function works. Very helpful links guys

 

[bustanutley]

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

 

[JohnnyC]

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

this is the exact info i was looking for....i love the search

thank you for posting that information

 

[Richard R]

When all else is lost go to --
Weber Carburetors Carbs 40 DCOE 45 DCOE 32/36 32/34 Jeep
Then scroll down to help, then 38DGAS and follow the idle setting to the LETTER. Work hard to get the fixed size idle jets to the size so the adjustable jet is between 1/2 & 11/2 turns. Get these right as they control the mixture up to a fair amount of REVs not just the low idle. After this is dead on then go to bigger or smaller main jets as needed.
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