I have been using the STE SK flow meter for balancing my carbs like most of us. The Jalpa uses 42 DCNF's and that little SK craps out at anything off-idle, making the flow measurement nearly impossible. I bought a four-column manometer and was measuring vacuum below the throttle plates, but that is a chore, the unit is finicky and not good for "pull over and make adjustments" tuning. At Concorso another Lambo owner showed me his Uni-Syn carb sync tool, which is adjustable for different flow rates. I bought one, its on its way, just curious if anyone has an experience with them? On the surface seems like a better tool than the STE SK and cost effective too. Edelbrock Part No. 4025 - Balancing Instrument Kits
Geno, I used one for all the SU and Stromberg carbs on the British cars. Always easy to use and to read. You just spin that inner piece to open and close the orifice to adjust for the volume of air. I hadn't thought about using one on the Webers, though. Hopefully you can get a good seal. Jeff
I have 1 and it works well, but unless u have full bell air horn it's not going to seal. This may work Image Unavailable, Please Login
The unisyn takes away most of the air and really becomes a vacuum gauge effectively killing the cylinder being measured. It also needs a flat surface to seal against. Most of us thought they really outlived their usefulness in the 60's. The STE on the other hand measures air flow and does not disrupt running. It can be left in place as long as you like. I have even seen shops that have 12 and just put them on and leave them while the entire carb tune is done. No way that can be done with a Unisyn. I have had an STE SK since the 70's and in all that time I have almost never seen a Ferrari mechanic use anything else except in a rare case when we went to the trouble of hooking up the 12 column manometer. What kind of trouble are you having with the STE SK? I haven't used it on a Lambo but I have tuned a lot of Ferrari's with it. Come to think of it, it has been used on several Lambos. I have never felt the need for one with greater air flow but for big displacement motors they make the STE BK. If you really need something different I have a 12 column mercury manometer I never use and would sell.
Thanks Brian. on the Jalpa its fine at idle, measuring around 3.5-4 kg, but when i get off idle, it almost pegs up in the upper ranges, where its difficult to discern how much air is flowing. I am doing my best, I but its hard to get a good reading due to the diminishing increments as the flow reaches the upper levels of the gage. If you try and sync it at 3k rpms forget about it, its pegged out. The only way you can do it is to sync with the plates tipped just a little forward (less than 2k rpm), and even then its hard to get a good reading.
i am curious about the manometers. I bought one (non mercury, some wheat-grass eco crap in the columns), and it gives very uneven readings bouncing all over the place. I would suspect the mercury unit doesn't being a heavier fluid. But i have no experience. I would love the give the mercury unit a shot.
I have used them a lot. Any fluid, including mercury bounces a lot and you get a headache watching 8 or 12 columns bouncing like that. Also I doubt you could rev it to 3000 without sucking the mercury into the motor. Seen that done a bunch. A million little tiny mercury balls get spit out the exhaust. When I am tuning one all I really do is set up the idle resting on the stop screws and raise the rpm via cable adjuster enough to get 8 or 9 kg on the scale to be sure the carbs flow the same on the linkage rather than just the stops. Your situation doesn't sound any different that what we faced doing 308's or Daytonas.
If you already got testports to connect to -maybe this tool could be helpful ? Manifold Pressure Tool - YouTube Harald
That looks promising Hoverland, is this your baby? Is it available yet? A "special" package w/ the exhaust gas analyzer tool for us guys would be sweet! If they could be run at the same time tuning would get a whole lot quicker...
For 3.5L displacement, that doesn't seem right (like your real problem is that you have some cylinders that aren't contributing useful work at idle). Can you be more specific about what conditions you do have at warm idle: displacement = 3.5L? warm idle RPM = ? warm idle ignition timing = ? average airflow per barrel at warm idle as measured by SK (in Kg/hr) = ?
As DIY I used that Uni-Syn tool on all my carb cars including the 308. I took a piece of large rubber hose and cut off a 2 inch piece of it. I used it between the carb throat and the tool to eliminate the sealing issue. Set my carbs up 27 years ago with that tool and haven't seen the need to do it again.
The Uni-Syn works fine, but you need the right size- they're not all the same. I have several, including one shaped like a racetrack. The surface that fits to the intake is thick sponge rubber, which if in good shape seals nicely. The real work is to make sure the carbs are correctly set up, meaning floats properly adjusted, butterflies correctly adjusted so all are completely closed at zero throttle, also no air leaks, especially at the ends of the throttle shafts. Of course all the bits (Webers) have to be the same- emulsion tubes, air & fuel jets, pump jet and so on. If someone's messed with these you're in trouble. All the Uni-Syn can do is tell you that the amount of air being drawn into each cylinder is the same- or not. If it's the same- that is, the ball floats at the same spot around the middle of the tube- you can then balance everything. I used to set up my Lotus twincams all the time this way, ditto the triple SU's on my E-Types, no real problem other than the lengthy process involved, especially on SU's. But it works. Overall a PIA which is why I love FI; the same goes for electronic ignition. I hate setting points. Good luck, and remember when tuning a car- "omit no tests". Cheers, Rich
For what it's worth, I use at least two of these things to tune engines, one always on the other bank. This has made it tons easier to see what the other is doing at part throttle to 1500rpm. A person is only ever going to get 90-95% there with these carbs anyway so there no sense beating yourself over the head once you get it close, not that you're doing that by the sound of things.
I saw this... "Salesprice will be NOK 5.500,- (approx EUR700,- GBP600,- USD900,-) ex VAT and ex freight. Boxed content is "Manifold Pressure Tool", software/drivers, Shielded USB cable, sensor hoses, see picture." Sure would make things simpler wouldn't it!!
Thanks for all the comments guys. When i get back into the country I will post a video showing the flow rate at idle and off-idle, and will also have the Uni-Syn tool by then and will report those results. The timing is set the factory marks, warm idle around 900rpm, and flow characteristics are the same (as close as I can get them) between all barrels (i.e. one isnt flowing much higher than the others). The distributor has a vacuum retard at idle drawing vacuum from below the throttle plates.
When Honda 750's first came out the Honda manometer was a set of 4 vacuum gauges with a little petcock in each hose to dampen the vacuum pulses. The manometer I have has little restrictors that look like plastic carb jets. It is a mercury unit but there is no appreciable bouncing. Years ago, not wanting to spend the money on a Honda gauge set, I bought 4 vacuum gauges and 4 radiator petcocks, mounted them on an ali plate, and it worked fine. I could close the petcocks just enough to dampen the pulses being careful not to close off the line. Tom
There was a fellow fchatter that put together a digital carb synchronizer. It was very well done and worked with a laptop. I think he planned on marketing it. When I get a chance I will look it up and post a link to the thread. Good for 2-12 cylinders and neat bar graph display.
I don't think the EPA liked THAT! Dad found me playing with mercury pirated from school, and packed it in sulfur to throw away...I think that's how he did it...
