weber 32/36 dgv, selecting jets, air correctors?

[recordsj]

1500 MG midget, weber 32/36 dgv tuning question

I understand the process of tuning for best lean operation with the idle mixture screw and idle speed screw. Then if these are not in the correct range to adjust the primary idle jet. What is the process to select the secondary idle jet, main jets and air correctors?

I just went through the process of needing to increase the primary idle jet size, but now I am wondering what I need to do to select the correct size for the secondary and the other jets?

 

[regularman]

I have not worked with the DGV on the 1500. I have one on a 1275 and I have worked with them as the Holley 5200 on small fords. The only way I found is trial and error. You got to put in the jets and run them and see how they do. You need a set of jets to do it proper, or a set of drills if you can find one. You got to get the car hot and then see how it all works. Not just idling to get hot. Take out and run it hard then come back with it really hot under the hood and see how it idles.

 

[recordsj]

One of the things that I am trying to do is increase the MPG (currently before the change I was getting around 22 mpg).

 

[regularman]

Yeah, you are off somewhere. I was getting 30 back and forth to work and 37 highway with the 3.9 and 4 speed and the weber. Now I have a 3.55 and 5 speed and it was too rich so I went down 3 main jets. A bit too lean now, so back up one when I get the chance. Best mileage so far is 43 just putting around on back roads, and 33 when driving it hard in town. 38 at lake of the Ozarks gathering running here and there and a few sight seeing trips. Have not checked a straight hiway mileage trip yet but, I am guessing high 40s if I run just 60.

 

[recordsj]

what do you mean "if I run just 60"?

 

[regularman]

Re: weber 32/36 dgv, selecting jets, air corrector

what do you mean "if I run just 60"?

Oh, just 60mph. 60-65 is around 3000 rpms for me.

 

[tosoutherncars]

Re: weber 32/36 dgv, selecting jets, air corrector

Hi... err... J?

Paul T.'s page lists the benchmark jets for the DGV / 1500. It's what my 32/36 came with as stock, and works fine.

https://www.teglerizer.com/dcoe/index.html#The DGV numbers

So that's primary idle 55, primary main 140, secondary idle 50, secondary main 135. If you started with that, and were getting 22 mpg, there must be something else at play here... You do have either a fuel pressure regulator, or a high-volume, low-pressure pump?

*edit* I misread, you meant you were getting 22 MPG with the old Z-S? What is your current jetting on the DGV? And what are the results of your 'best lean' setting? You're not battling with the (very common) manifold leaks throwing everything off, are you?

 

[recordsj]

Re: weber 32/36 dgv, selecting jets, air corrector

22 mpg on the weber 32/36.


i have tested for the manifold leaks by spraying carb cleaner around the carb and manifold when it is running and didn't experience any engine revving up.

 

[tosoutherncars]

Re: weber 32/36 dgv, selecting jets, air corrector

- Current jets?

- How many turns from bottom is your mixture screw?

- FPR / low-pressure fuel pump?

- Did you advance your timing to compensate for the DGV? (They require more advance)

- Other driveability issues? Heavy stumble on accelleration, etc?

 

[recordsj]

Re: weber 32/36 dgv, selecting jets, air corrector

car: 1500 mg midget, weber 32/36 dgv

-current jets
prim idle 60 (just put in the 60, before it was 55 which I was getting 22 mpg, don't know new mpg yet)
sec idle 50

- FPR/ low-pressure fuel pump
what is FPR?
haven't deadheaded the fuel line to check pressure yet

- timing
my timing is set to 10deg BTDC, how much more advance do they need?
I noticed that for a california s/n engine (which mine is), but has the smog control components removed with the engine in a 1974 car. the timing spec is supposed to be 2deg ATDC, why the difference?

- driveability issues
don't notice any other issues

 

[regularman]

Re: weber 32/36 dgv, selecting jets, air corrector

car: 1500 mg midget, weber 32/36 dgv

-current jets
prim idle 60 (just put in the 60, before it was 55 which I was getting 22 mpg, don't know new mpg yet)
sec idle 50

- FPR/ low-pressure fuel pump
what is FPR?
haven't deadheaded the fuel line to check pressure yet

- timing
my timing is set to 10deg BTDC, how much more advance do they need?
I noticed that for a california s/n engine (which mine is), but has the smog control components removed with the engine in a 1974 car. the timing spec is supposed to be 2deg ATDC, why the difference?

- driveability issues
don't notice any other issues

Does it smell rich with the top down? The only time you should smell richness is when you depress the pedal and the force pump shoots an extra squirt of fuel in, then the smell should go away.

 

[recordsj]

Re: weber 32/36 dgv, selecting jets, air corrector

what would you recommend to advance the timing to compensate for the DGV?

 

[tosoutherncars]

Re: weber 32/36 dgv, selecting jets, air corrector

OK, timing aside for the moment...

If you're still running the stock mechanical fan, you're overwhelming the carb with fuel. The stock pump puts out something in the neighbourhood of 6-7 psi, the DGV requires something like 1.5 - 2.

IMHO, trying to tune it without first addressing fuel supply is really tilting at windmills.

If you bought the kit new, the instructions should have mentioned fuel pressure, you can either put on a Fuel Pressure Regulator (FPR) or a low-pressure fuel pump. Avoid the little cube pumps... Carter makes a nice low-pressure pump (part# 4070) as do others.

 

[recordsj]

Re: weber 32/36 dgv, selecting jets, air corrector

I have one of those electric "cube pumps" you talk about, so I guess it is putting out too much pressure. Would having this type of pump have an affect on low MPG?

 

[jlaird]

Re: weber 32/36 dgv, selecting jets, air corrector

Cube pumps come in two styles low and high pressure. Get the model number off of it and google it to find out what you have. Lo is the key.

 

[tosoutherncars]

Re: weber 32/36 dgv, selecting jets, air corrector

Certainly, if it's high-volume. It would affect mixture control, as well... Check the specs on your pump. If it's the type to normally feed Zenith or SUs, it's much too high-pressure for Webers.

A quick search (top right-hand corner) of the Spridgets forum, using "Weber DGV" as keywords will pull up a number of related threads.