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Dual Weber jetting ????


Tim240z

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Guest Anonymous

I dont know the correct #s for your set up,and if there is any other add ons (header/big exhaust/cam)to your car or the donor car,they probably wont help much.I have a 32/36 dgev on an L20,and other Webers on other cars as well.The first thing I would check is fuel pressure.Webers only like 2-3 lbs.Next,you need to determine where it is rich.Idle(air/fuel mixture screw,works like faucet.Remember you are adjusting the fuel supply.You want the leanest smoothest idle with the idle SPEED screw out as far as you can.This will help with the transition between idle and light throttle ). Off idle w/light throttle(idle jet on primary side.Its a brass screw on the primary side of the carb,about midway.The screw is the jet holder). Or medium throttle above about 2500rpm (main jet,primary side,in the bottom of the bowl) And then WFO (secondary main.bottom of bowl)The jets you can see from the top looking inside are the air correction jets/emulsion tubes.They determine how much air is emulsified/mixed in the main fuel circuit on its way through the passage.Most of the time the main jet change will get you close enough.

The way to find the fat spot is to grab a plug wrench and DRIVE the car in each of these positions for 10-15 seconds,and turn the car off.dont let it idle,just kill it in that position.Pull a plug and look at it.whichever position turns it black,thats the fat area.The lower rpm range will usually chug or blubber if its fat,or spit and hesitate if it is lean.I only move jet sizes up or down 1 size at a time.it costs more,but you can go from fat to lean real quick, and then your lost.Also,buy a good syncronizer. Hope that helps. 2thumbs.gif

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Guest Anonymous

Hey, been trying to make heads or tails of my webber book (webber carburetors, by Pat Branden) haven't been able to figure anything solid out. I did however mention your problem on the other Z forum I am in, keep you rfingers crossed maybe someone there will have some answers. I'll check in if I figure out something.

 

P.S. what do you know about the carbs, venturi size what jets are in it, their condition etc...

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I had the settings scribbled somewhere but dont see them right now...

 

What I do have though, is the jets for the 32/36 DGAV which I think will be the same, other than the automatic choke.

 

Primary/secondary idle jet .50mm/.50mm

Primary/secondary main jet 1.40mm/1.40mm

Primary/secondary emulsion tube F50/F50

Primary/secondary air corrector 1.70mm/1.60mm

 

I will try to find my other sheet.

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Guest Anonymous

Hey Mudge,

Here is what I've found so far. The 32/36 DGV 7A were a production carb for escort GT (somewhere) At any rate one was used for a 1298cc engine, so the production settings should be a good start point for you.

 

Pri/sec venturi 23/24

Aux venturi 3.50

Emulsion tube F50/F6

Main jet 1.25/1.30

Air corr 1.80/1.95

Idle jet 0.55/0.50

Pump jet 0.55

Needle valve 2.00

 

Also I would check the progresion circuit, that is the key to smooth transitions between idle and WOT (and everything in between). Unsure if these will help. Seems like it should but what I do know about webbers....nothing works in a logical way when it comes to jetting etc...

 

jeff

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One of the two books I got from Amazon is the Haynes TECHBOOK Weber Carburetor Manual

 

There are many DGAV listings for OEM setups, but only ONE DGV listings and it is a Capri 1600cc engine. There is listed a 32/36 DGV 5A/05A and DGAV 8A/08A, the jets are the nearly identical. So with a generic estimate we are looking at 30-35% too much fuel.

 

There is also a Weber jetting conversion chart, guess what, no DGV listings, almost all sidedrafts. :(

 

The 2 liter Capri is all DFAV/DGAV listings.

 

http://www.theape.com/jets.html

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Guest Anonymous

I found that the DGV came on a 2 liter off the internet somewhere so I wouldn't doubt that it could be wrong. Mudge, does that book that lists the DGV on the 1600cc give the main jets as 140/135. Or the same as what is under this link you provided http://www.efn.org/~msayer/weboem.html.

If so that wouldn't be two far off from what we are running with each carb feeding 1400cc (assuming we are running 140/135 jets). I know Pegasus Racing has DGV jets for a little over $4.50 a piece. As a test to drop down one jet (i.e. go leaner) could probably reverse the main and secondary jets and take the car for a drive to see how it runs. This should work since you don't get into the secondary jets in normal (non-aggressive) driving. If the plugs still look rich order a couple of 130 jets and see how that works. That other link you provided http://www.theape.com/jets.html provides a good rule for determing the right air corrector jets based on how you adjust your main jets.

Thats probably what I'll try once I get my floor welded in.

I tried posting this question for DGV jet values on the Internet Z car club mailing list (1000+) readers, only one bite and it was not helpful. :mad:

I got a fuel pressure gauge this weekend so I'm going to see what that is. Do you guys know what the recommended psi is for these DGVs? It seems like I heard 3 psi.

Later,

Chad

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I wont be feeding 1400cc for awhile, I'm still using the 2.4L engine F54 is awaiting a rebuild in a couple months.

 

The settings in the Haynes match those on the page below:

http://www.efn.org/~msayer/weboem.html

 

2.5-3.0 PSI is what these Webers like supposedly, Haynes and other sources say the same. I'm going to order about 3 different sets of main/secondary jets, since I'm running pretty darn rich with only a 2.4L setup. I am not sure how linear the changes are since I probably wont play with the emulsion/air stuff for awhile and just change the fuel jets. If I dont go FI sometime in the future then I imagine I will have to learn more to get the most out of the setup in terms of linearity and not having soft spots, since changing only one thing, and by such a drastic amount can screw up the balance of the carb.

 

The Haynes also lists DGAV stuff and they look pretty darn similar (no supprise), in terms of jetting/tubes used. However it looks like the DGAV was mostly used on larger cars, 2 liter, and still only a single carb. I find this for a Cortina (Toyota), and it wasn't just the fuel jets of course that were changed, since again the linearity of the carb would be hurt without changing everything that has anything to do with fuel metering. I will probably gain a massive improvement just playing with fuel jets for now, but since I have to wait a couple days to order probably anyway I may figure something else out better. Not sure if any places are going to be open tomorow.

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Guest Anonymous

Hey all

The only difference between 32/36 dgv/dgev/dgav is the choke.Dgv is manual,dgev is electric,dgav is water(aqua).I dont know why you guys are trying to find magic numbers in a book that has no idea what climate or altitude you live in,or other mods to the car.If one of you did a plug test and found the right combo,it would only apply to THAT car.There's only one way to get it right.Check the fuel presure,sync the carbs,and do a plug test.Sorry to sound like a d#%k,but if you read the jetting charts in any Weber book,at the top of the page it says THESE ARE BASELINE FIGURES ONLY.THE CALIBRATIONS SHOWN WILL ALLOW TO RUN THE CAR IN ORDER TO VERIFY JETTING.If your car already runs the jetting charts are worthless.Again,sorry to be a jerk.

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Here are my jetting specs:

Primary fuel:140

Secondary fuel: 135

Primary Emulsion tube: F50

Secondary Emulsion tube: F6

Primary Air: 160

Secondary Air: 165

pump jet: 50

Venturi 3.5

 

I have used an industrial (read very accurate) A/F ratio meter with wide band O2 sensor and it is running lean (about 17:1) while cruising. I did manage to get the idle A/F ratio perfect, but need to play with the jetting to richen up the primaries.

 

HTH.

Tim

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Originally posted by berZerker:

if you read the jetting charts in any Weber book,at the top of the page it says THESE ARE BASELINE FIGURES ONLY.THE CALIBRATIONS SHOWN WILL ALLOW TO RUN THE CAR IN ORDER TO VERIFY JETTING.

If I could even find one, it would give a baseline direction to go in, but I can't find one in the books I have. Sidedraft data is fairly plentiful and thats whats recommended on these cars, but thats not what I have, and I'm not going to spend $1400 to fix a jetting issue, I'd go EFI way before that.
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TZ, naw not painted yet, but I did shoot primer on the driver's side fender and headlight bucket (fender was black..new panel with factory primer, and headlight bucket was yellow), and where the side molding 'clips' were ground off (which made it look like I did a run through South Central LA at midnight and got sprayed with 9mm rounds) I taped off a 3 inch stripe and shot primer. Looks better now, but still like a project car. Not too worried though. This car drives like it has 30,000 miles on it, not 170,000 miles, and since I replaced the Clutch, it's smooth as silk!!

Now to install the IC, up the boost, do the 240sx tb conversion etc etc.....

 

I also found a brand new looking turbo at the JY and paid $90 for it. It was so clean, not even an oily fingerprint on it!!!! Owen helped me pull it...he was amazed too. I think I will do a blowthrough system on the 240/weber carbed motor, and really jack up the jetting.

Tim

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