This may not be apparent if you use the older Unisyn flow gauge which has coarse readings. This is because the plenum type manifold that they are on distributes fuel unevenly. The hesitation wasn't nearly as bad as stock, but still wasn't smooth. The dreaded flat spot from idle to 3K rpm is gone! I thought your float might need some adjustment. But once I got everything dialed in correctly things really began to shine. Look closely at the lower half of the butterfly.
Light throttle under load is lean but not too bad, maybe 15. Unfortunately, we don't do so many race engines anymore. I would not worry too much about it as it should never occur when out on the stages. Along with leaner fuels, any modifications to an engine to improve performance can compound the lean effect and require more mixed fuel volume. Since the fuel level in the emulsion well can vary dramatically compared to that in the fuel bowl proper fuel pressure is required to properly supply fuel demand in the well. The Synch tool will also alert you to other problems in the system like Bent throttle shafts, etc.
Repair or replace the linkage as needed to make them work together properly. If there are more holes at the top then the air fuel ratio will be weak at low rpms. Those values are not valid for high-revving 6-cylinders. After several runs with all the usual suspects F2, F9, F11 we looked at the results in the same way Vizard describes and I changed to another 'family' and things improved. Assuming you have no vacuum leaks this is a very simple process. That said this is the real Cliff Notes version of tuning the power circuit of these carbs.
The bigger the Idle jet number the richer the jet. If you want hard numbers, the factory default values of 30mm choke, 115 main, 200 air, F11 emulsion, 45F9 idle on my L28 gave surprisingly drivable and torquey results. Start with the F11 tube or even better the F15 a bit richer on topend and see how it goes. Once I got past the fear of taking apart the carb, and realized it was only 6 screws and a tiny tiny clip, I realized it is super easy. No idea it is working. Wish I knew this trick years ago! Or maybe the opposite is true. Its features include: ball bearing throttle shafts, piston type accelerators pump circuits, a wide variety of throttle bore sizes.
If he does have more, from what I've been testing. So it looks so far like the carb came stock with the following jets: Primary barrel air correction jet: 170 Primary barrel main jet: 140 Secondary barrel air correction jet: 160 Secondary barrel main jet: 140 Haven't had a chance to see what the idle jets are or which emulsion tubes are installed. I think that you van run modern ignotion without anyone noticing. As you may know both Aux. This overlap allows an exhaust pulse to feedback and disrupt the fuel mixture coming down the intake runner from the carb.
They look scary at first but once you put a couple back together you'll find them easy from that point on, really. If this does not work, depress the accelerator fully and hold it open while turning the engine over for 5 to 15 seconds, then close the accelerator and try again. Turn the mixture screws in until the idle starts to stumble and get rough. Once the unit is synchronized and the idle mixtures are dialed in to give you the smoothest possible idle, you can hang up your Unisyn and screwdriver til' next spring, because now it's set! F2 and F7 are recommended when using alcohol fuel. This circuit has three primary elements you should concern yourself with - the main jet itself, the emulsion tube and the air corrector. It's done the same way you do a single four barrel, except in this case, you can listen to each cylinder separately.
All products purchased should be inspected, measured, cleaned and properly assembled prior to installation. The mild acceleration allows a rush of air through the main venturi in the attempt to satisfy the low pressure intake vacuum below the throttle plate. While it is possible to achieve improvement in two of these criteria, it is not possible to simultaneously satisfy all three. Interchangeable venturi and accelerator pump cams add to the versatility of these units, which are particularly useful in applications where engine compartment limitations dictate a compact-size carburetor. Replace Idle Jets with half-size larger. If the progression is weak then the engine will nosedive when moving the accelerator from smaller to larger throttle openings. I have an earlier version of the e-tubes that still need some work, going lean at full throttle at low rpm.
You cannot make jet decisions unless you kow what you are starting with. It wasn't perfect though and idle was still slightly choppy. This is all just a base line to get you started. But on the road the instant-torque feel was reduced, less snappy when I punched the throttle. Available Options: Emulsion Tube: This product was added to our catalog on Tuesday 23 February, 2010. This is the function of the emulsion tube.
It is much more important therefore to select the main venturi for best driveability, once the venturi size has been selected, then the appropriate carburettor size can be arrived at. I will be tuning a 2 litre pinto tarmac rally engine soon with twin 50 webers which have a unique set of high velocity chokes, I have a number of different emulsion tubes, F7, F11, F16 and one or two more, can someone tell me what the differences will be on the fuel map vs rpm? I'm not saying Dave Vizard his test work is fake. It may take you four times longer, but it's no more difficult at all. Under wide-open throttle acceleration the emulsion tube plays little part since the overriding effect is that of the main and air correction jet. So I graph across a shorter section of the same run and selected a portion where I was not idling the rpm and tps data allowed me to do this.