Weber 38 DGAS : info + settings + tuning

[Weber Sarge]

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

 

[ErikinSC]

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.

 

[ErikinSC]

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.

Mark and tighten 1/8" additional turn.

Now run engine - check fast idle speed.

 

[ErikinSC]

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'

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.

 

[ErikinSC]

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.

 

[ErikinSC]

Remove the top assembly - I'm getting really good at NOT loosing that E-clip that holds the choke linkage.

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

 

[ErikinSC]

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

Just as @Weber Sarge expected. F50s.

 

[ErikinSC]

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.

 

[ErikinSC]

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 :

* once were back to full temp :

 

[ErikinSC]

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.

 

[ErikinSC]

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?

 

[ErikinSC]

Going to swap back to the 150 mains and try the 55 idle jets next.

 

[ErikinSC]

Double checked the float (plastic) and I'm at 38 and 46

Dropped

Weber says 35 and 51.... Adjusting.

And fixed. Damn that's aggravating.

 

[ErikinSC]

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.

 

[ErikinSC]

Grease pencil 'Note to Self' :

 

[ErikinSC]

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.

 

[Weber Sarge]

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

 

[ErikinSC]

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.

 

[JohnnyC]

i have heard good things about all those options for dizzys

I run the lesser known Crane Cams electronic ignition in my own dizzy

I also note to self on my hood... And it looks like I'm due for a tune up lol

 

[Weber Sarge]

More than likely you'll have to go down on main jets with those compression numbers - it's pretty low . Nice part of the Weber is it can be tuned to fit the engine , which is also part of the problem with Webers - lol .
Sarge