help with 2.0 weber carb jets, I'm soooo confused!! Options

[BK911]

I have two different charts that give two different settings:

28 vents, 1.35 main and .55 idle or
32 vents, 1.45 main and .60 idle.


Bought a set of EMPIs for a 2.0 which came with:

28 vents, 1.25 main and .52 idle


Read MANY threads here, samba and type4forum on proper jetting and vents and they are all over the place.

Would like to get these together and installed asap.

Is the current set up good enough for daily driving to/from work?
No track, no AX, just cruising around TN back roads.

[amfab]

I have two different charts that give two different settings:

28 vents, 1.35 main and .55 idle or
32 vents, 1.45 main and .60 idle.

Here is a thread on this topic:

http://www.914world.com/bbs2/index.php?showtopic=89838

I am definitely no expert, but I too was looking for an easy answer for my 2.0.

After lots of searching I came up with some info from Solex and Mark Harney to add to your confusion.

What I gleaned was that jetting for a particular set up can vary and you need to mess around with your particular motor and driving style and power band desires.

But:

Solex has a formula for carb barrel sizing that says the barrel size should be .82 times the square root of the of the size of the cylinder in Cubic centimeters (2.0L divded by 4 cylndars=500cc) times the max RPM of the motor (5600 for a stock 2.0) divided by 1000—so 5.6.

I will show the work:

500cc x 5.6=2800
Square root of 2800 is 52.92
52.92 x .82 (the Solex coefficient) is 43.39

So Solex is saying that a 40–44 diameter bore is a good size.

Then Mark Harney’s formula says:
Idle jet-1.6 x venturi
Venturi-3-5 less than intake valve diameter (42 on a 2.0)
Main Jet-4.2 x venturi size
Air Corrector-200 as a starting point

Based upon the above information for 40idf a good starting point is:
Idle jet-54.40 (round to 55)
Venturi-34.00
Main Jet-168
Air Corrector-200.00

These are just the best generic formulae I could find. Many people around here have A LOT of empirical experience with this so read their feedback.

According to these formulae I should run in a 36idf (rounded):
Idle jet-55
Venturi-34.00
Main Jet-150
Air Corrector-200.00

But I can't get a 34 venturi in a 36IDF like the Solex formula suggests so with the 32 venturis, using the Harney formula I should run:

Idle jet-50
Venturi-32
Main Jet-150
Air Corrector-200.00

I never got to do this because I pulled the car off the road due to rust issues, but the formulae seemed to reflect the problems I was having with my car.

The car popped a bit on deceleration—lean—indicating the idle jet is too small.
Power got a little flat toward the top indicating a little bigger min jet may have helped
My set up was
Idle jet-47.00
Venturi-32.00
Main Jet-145.00
Air Corrector-220.00

So my symptoms are exactly what the formulae would have predicted.

Of the two options you suggested, I think the 32 vents, 1.45 main and .60 idle would be the closest to what the above formulae suggest. I don't know if you can get 34 venturis.
I think that the suggestions about the smaller venturis are probably better suited to the smaller valve heads of a 1.7 or 1.8 or type I motors. The 2.0 heads have a big intake valve.

I would probably start with:
Idle jet-50 or 55
Venturi-32.00
Main Jet-155–165
Air Corrector-200

Again, there are many here with a lot of experience with this—way more than I have. This is just some info I researched that I hope adds to the conversation.

-Andrew