38 DGAS emulsion tubes?

22982 Views 29 Replies 16 Participants Last post by First opel 1981, Aug 29, 2013

N61WP

Discussion Starter · Jul 4, 2003

Been having an e-mail discussion with Mach1Tom about tuning the 38. I have went up to 150 jets from 142 and the car seems to run well. From the plugs, it is just slightly rich, (I perfer it that way for safety with my 11:1 compression). It has idled fine from the begining. I have not touched the emulsion tubes. Tom has pointed out to me that the Guru's have recommended changing to F-66 tubes in several tuning posts.

Now, to show my ignorance to the whole group(again).....What exactly do the emulsion tubes do?

Happy 4th to all,
James

Thanks for the spell-check, Gary!

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Gary

· #2 · Jul 4, 2003 (Edited by Moderator)

From the 'net:
Emulsion Tubes

Emulsion tubes control the metered fuel and air introduced into the Carburetor. When air enters the emulsion tube through the air jet and fuel enters through the the main fuel jet this condition emulsifies the fuel delivered into the carburetor. The emulsion tube has a series of small holes from top to bottom which regulate the fuel mixture. These holes allow air and fuel to enter the main circuit and emulsify fuel. Low speed engine conditions or engines at idle do not require use of the emulsion tube or the main circuit. As engine speed increases the fuel level in the float bowl drops uncovering these holes and allowing air from the air jets to enter the main circuit resulting in a lean mixture. As the engine speed increases the fuel level in the float bowl continues to drop. This uncovers even more of the holes in the emulsion tube, which makes the air jet have a greater effect on the low to high rpm fuel delivery mixture.

When RallyBob jetted my 38DGAS There was a slight hesitation when you hit the throttle. (I barely noticed it) He said it was due to the E-tubes. I put the F-66's in and the flat spot went away.

Spell check... you noticed.

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N61WP

Discussion Starter · #3 · Jul 5, 2003 (Edited by Moderator)

Thanks for the good explanation, Gary. I'm saving it to my Opel Guru file...you are in good company! I guess I'll order a F66--sounds like a good rainy day project, and it doesn't seem to want to quit raining lately. I may have to give the GT up for an Ark.

James

Mach1Tom (R.I.P.)

· #4 · Jul 5, 2003

Yes Gary, thanks for the great explanation. I know I coundn't have explained it that good.

Tom C

RallyBob

· #5 · Jul 5, 2003

N61WP said:
I guess I'll order a F66--

You need two emulsion tubes....

Gary

· #6 · Jul 5, 2003

Mach1Tom said:
Yes Gary, thanks for the great explanation. I know I coundn't have explained it that good.

Tom C

Explanation courtesy of "Google". I just copied and pasted. We need to compile one complete article on the Weber.

sleeper

· #7 · Jul 5, 2003

I have a very similar situation with a 32/36, hesitation on acceleration from idle, primary jets a tad rich would the same emulsion tube, f66 be usefull or do they use different ones? TIA

Gary

· #8 · Jul 5, 2003 (Edited)

I used to believe that F-66's were also recommended for the 32/36. I got mine from Jam engineering. http://www.jameng.com/

Edited after reading RallyBob's post

RallyBob

· #9 · Jul 5, 2003

Personally, I've never felt the need to change the 32/36's emulsion tubes when rejetting them. Unless the 32/36 was originally from a non-Opel application.

sleeper

· #10 · Jul 6, 2003

I have no idea what the carb was previously on but odds are it wasn't an opel, however it seemed to have the stock jetting for similar engines listed in the haynes weber book, how do you tell which tubes you have? is it just stamped on them? thanks

N61WP

Discussion Starter · #11 · Jul 13, 2003

Just changed to the F-66 E-tubes on the Weber. I was skepticle when I compared the 50's I was removeing to the new F66's. The holes in the 66 are much smaller. Did it anyway, as the "Opel Gods" had spoken. Took the car out on the road for a 10 minute hard drive. Noticed no difference rowing through the gears. Still hit 90 pretty quick.

Retuning home, came through the neighborhood. First stop sign, something felt different. By the third stop sign, it hit me. I was taking off from the stop very easily. Since building this engine, I have always had trouble taking off easy from a stop without blipping the gas. I figured it was due to the light flywheel and non-slip clutch. I went back around and did more stops, just to be sure.

As usual, the Guru's were correct!
Thanks Guys, keep us wannabe's straight!
James

Rallye

· #12 · May 14, 2004

Weber setups....

It would be very nice if we could have a database of the different setups for the Webers that list the Engine size and modifications, the model of Weber and the jets and tubes that worked with it. Then when someone wanted to know, they would have a good starting point.

Just thinking out loud....
Elwood...

opelrun21

· #13 · Sep 28, 2004

finally got my jets and emulsion tubes in for the 38 DGES. How hard is the install for the tubes and do I need any rebuild pieces or gaskets? The carb is brand new I've statered it twice, and it was odvious it was running to rich.

thanks, Matt

she's about to hit the streets of Knoxville once again

nobody

· #14 · Sep 28, 2004

Ok this may or may not be that relevant to the current topic but I does have some interesting info about weber tuning. Not long ago I was informed of a car being parted out that was built to a 2.0 with twin sidedrafts in Germany before it was brought back some years ago by a member of our armed forces. This was or is a true German GT on US soil and some of the info of the weber jets had me very interested. I just got back and they were sitting at my door. Mains are F11 with 115 main and 170 airs idles are 45F9 and they have 30mm chokes. I didn't buy them just for a nice set of jets that are very close to the motor I have. I kinda liked the Irmscher pair they came with.

opelwasp

· #15 · Sep 29, 2004

opelrun21 said:
finally got my jets and emulsion tubes in for the 38 DGES. How hard is the install for the tubes and do I need any rebuild pieces or gaskets? The carb is brand new I've statered it twice, and it was odvious it was running to rich.

you will need a flathead screwdriver and thats it. just pop the top off and unscrew the mains and air correctors and slip in the new ones. too easy.

opelrun21

· #16 · Sep 29, 2004

got them in last night what a difference. fixed everything that was wrong, and it was to easy!

kwilford

· #17 · Sep 30, 2004

opelrun21 said:
got them in last night what a difference. fixed everything that was wrong, and it was to easy!

What sizes did you install, and what came out?

sawdust

· #18 · Jul 24, 2007

32/36 Dgv 05a

Someone have a picture of the emulsion tubes.
I got bad hesitation from stop to go.
Carb set up:

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RallyBob

· #19 · Jul 24, 2007 (Edited by Moderator)

sawdust said:
Someone have a picture of the emulsion tubes.
I got bad hesitation from stop to go.
Carb set up:

The numbers '160' and '170' are the air correctors. When you unscrew them, the emulsion tubes are below. They are a light press-fit, and can sometimes be a PITA to remove.

FWIW, the emulsion tubes are rarely (if ever) the culprit with a 32/36 Weber. I only change them out on the 38 DGAS models, since that carb was never designed for an inline 4-cylinder engine.

I'd look for other more obvious issues like vacuum leaks, ignition timing, bad accelerator pump diaphragm, etc.

jvandyke

· #20 · Aug 10, 2007

N61WP said:
Just changed to the F-66 E-tubes on the Weber. I was skepticle when I compared the 50's I was removeing to the new F66's. The holes in the 66 are much smaller.
James

Guess this tells me that higher tube numbers mean smaller holes? I was thinking of mess'n with my F50s to emulate F66 by making the holes a tad bigger, but making them smaller is a bit harder!

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