Weber 38 DGAS : info + settings + tuning (1 Viewer)

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Don't sweat the number of turns on the idle speed with Spanish 38mm models of the DGV class . It's not uncommon for casting differences to change the distance a bit . It is somewhat important to balance the number of turns out on the idle jets - that should be corrected . Once you equalize the idle mixture screws and set the correct idle speed it should run very smoothly , unless you have a weak cylinder or two . Small things show up running these carbs , they are not as forgiving as the stock units on any engine .

I'm curious - do you know what number is on the emulsion tubes below the air corrector jets ? I would assume it is an F50 , but one never knows ...

Remember , idle jet size is determined by driveability - if it wants to stumble a bit or cough just off idle , idle jet size should be increased . One key to know the jet size is correct is having a very sensitive throttle - input should produce very rapid changes in the engine , it will drive like fuel injection when it's right .

Sarge
 
I'll open it up again tomorrow mid-day. Will check the emulsion tube; i looked last time I cleaned everything, but didnt write the size down. F50 sounds - nevermid - I will check. No ASSumptions.
 
Electric choke adjustment - holding throttle 1/3 open, loosen the 3-7mm bolts on electric choke, turn round electric choke housing until choke butterflys close.

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Mark and tighten 1/8" additional turn.

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Now run engine - check fast idle speed.
 
After I ran engine, tried to reset fast idle -but it's already 81F so I'm not really sure how we look.

I turned off engine, pushed butterflys closed (softly) and this is approximately what I look like 'cold'

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Choke slightly open. When I started engine 'cold' she Idled without stalling after 3 engine revs today. Will check again in October when it gets cold again. LOL.
 
Time to open and check emulsion tube #s. Main jets should be OK at 150.....?

Then maybe consider going back to 55 idle jets. And retune idle again.
 
Remove the top assembly - I'm getting really good at NOT loosing that E-clip that holds the choke linkage.

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And let's check the Emulsion Tube #s. They are under the Air Corrector Jets (mine are 200).

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Without removing the carb base, you have the option to use a scribe to pull the emulsion tubes up.

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Just as @Weber Sarge expected. F50s.

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Trying a slight change.

upped the mains to 155
Air corrector to 170
Leaving idle jets as 50

Will retune and see how we do. I didn't feel that I had the top end with the 200 air correctors. I know, I'm changing 2 jet sets - not one set. It's still early today.
 
Baselines the carb: idle speed 1/2 in from contact. idle jets 2 full turns out.

I read somewhere that unspoiled re-install the air filter to get a true air flow scenario while adjusting..... So, time to tune :

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* once were back to full temp :

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So, with the 155 main, and 50 idle jet - when setting lean idle, turning fender side idle jet all way I did nothing.

I read 1 main jet change is equivalent to 3 idle jet size changes - is this correct? Going to change the idle jets (up to 60) and retry.
 
With 60 idle jets - all the way made an improvement. This time I will change to the 55 idle jets and see what gives.

Could I need to change the main jet back to 150 from 155? Or increase to the 160?
 
Going to swap back to the 150 mains and try the 55 idle jets next.
 
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Double checked the float (plastic) and I'm at 38 and 46

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Dropped

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Weber says 35 and 51.... Adjusting.

And fixed. Damn that's aggravating.
 
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Alright, timing is @ 10* BTDC (guesstimating my red dot is 1/4" slightly below Timing pointer.... But still bouncing around pretty significantly.

150 main jet.
170 air corrector
50 idle jets. Both turned 1 turn out (w-in 1/8 turn of on another.)

Button it up and going for a ride. Maybe I got it this time.
 
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Grease pencil 'Note to Self' :
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SUCCESS AGAIN ! My truck drove very good. Aside from finding a dyno shop (I Googled it - there are supposed to be 2 here in Charleston) to prove that I have a good tune, in going to leave the settings here.
 
Should be able to run 50 to 60 idle jets , 145-150 mains and 165-180 air correctors on most Cruisers . Compression checks help narrow that margin down as all engines are different .
As I said - throttle response should be very crisp and sensitive . Main circuit should be the same under a load - if seems to take a long time to accelerate , say from 35-55mph in 4th gear it's probably too rich . You can do a main circuit plug check at cruise speed by shutting the engine off without lifting off the gas pedal and hitting the clutch at the same time . Let it cool for awhile and pull #'s 2,4 & 5 . Color should be a very light tan , no ash , no black .

I set the float a bit different - I only use the top distance and allow for about 10mm of drop , it helps to limit the drop a bit more offroad .

Sounds like your distributor is worn or something is off - the timing should be rock steady at idle .

Sarge
 
thanks for the observations. 150 main is the smallest i have to work with (for now, will source 145's for testing). I'll try the 35 - 45 mph acceleration test and report back. I can try to check the plugs by driving to work, turning in and

March 22, 2015 Compression tests, warm and dry :
#1 - 109 #2 - 114
#3 - 111 #4 - 109
#5 - 105 #6 - 116 I did not do 'wet' test.

Im thinking the same thing on the Dizzy..... But it is a new(er) non-USA unit - 2 years old I think. It was suggested that I consider using a Toyota FJ60 dizzy, later model - small cap - electronic OEM instead of a Trollhole or Petronix option. Some reading to do, I have.
 

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