Hey Guys, I just my Uni-Syn syncho tool for setting the dual carbs on my 50 Chevy, I got it off ebay for a whopping 5 bucks shipped-problem is there are no instructions for it. I was wondering if anybody has a manual, or instructions on how to use one. I looked around the internet with no luck, but might have not been looking in the right places, so any help would be greatly appreciated!!!!
And another http://www.jalopyjournal.com/forum/showthread.php?t=412106&highlight=uni+syn Use the search criteria I used and there are many more, including one by Ryan.
Disconnect the throttle linkage from the carbs. Start the engine, and run until the engine is at normal operating temperature, and that the chokes are completely off on the carburetors. Set the throttle positioner screws approximately an 1/8 of a turn at a time on each carb until the idle approximates desired RPM. Open the center adjustment (the little thumbwheel) on the Uni-Syn to the wide open position, and set the Uni-syn on the carburetor of your choice (it makes no difference). Adjust the control knob such that the plastic bobber is directly in the center of the column. Remove and replace the Uni-syn and verify that the engine does NOT change RPM with the addition/subtraction of the Uni-syn. Move the Uni-syn to the other carburetor. Adjust the throttle positioner screw of the second carburetor such that the plastic bobber is directly in the center of the column. When the carbs are synchronized, one should be able to move the Uni-syn from carb to carb with no change in RPM and no deflection in the position of the plastic bobber. If the idle is too high, again adjust the throttle positioner screws on both carbs to the desired RPM, and repeat the synchronization process. Install the linkage between the two carburetors. Make certain there is NO movement of the throttles. With the throttle linkage installed, verify the synchronization. If adjustment is needed, remove the linkage, and try again.
There is a thumb wheel on top that moves a cone in and out of the bore. Start with it out a ways and place the unit over a carb inlet. Screw the cone down untill you get the ball floating about half way in its tube. Check the other carb. Adjust the carb to get the ball in the same place. Go back and forth between carbs untill you get the air flow the same and the engine idling where you want it.
Not much to know really. The plate in the center is for calibration. The clear tube should have a small plastic piece that moves upwards with vacuum. Place the Uni-Syn over your primary carb ( or whichever one you wish to call primary) when the motor is fully warmed up and adjust the plate until you get a good baseline number. I always shot for around dead center. Then move it to the secondary carb. Adjust the idle on the scond carb until it comes in close. go back to the first since changing the second can affect the other. And check again for equal numbers between the two. If it is off, go again. Of course you want to idle to remain correct for the engine so a small tach of some sort in the engine bay to monitor is a good idea. I have grabbed cheap Sun tach or dwell meters to keep an eye. But if you don't have access to one, try your best to listen and keep it right. You may have to go back and forth a few times to get it right off idle. Some people will check again around 1 or 2 grand to see how much difference there is at higher ranges also. The concept is the same as a basic pair of vacuum gauges for motorcycles. Basically you want them to pull equally at all ranges, or at least as close as possible. Sloppy linkages, or leaky carbs will cause issues of course, but this should go without saying. And if you have more than two carbs the concept is the same, except you want to make changes along all three. Only re-adjust the baseline at the primary carb though. You want to be certain that you work off one for a baseline.
Thanks Guys, I ahev something close to this from the Carshop, but I thought it might be more complex. I was wondering if anybody has the issue of the va*** being dramatically different in the carbs due to the va*** adavnce. Mind you the car has not been tuned yet, we are planning on trying to tune it monday, but just placing the palm of my hand by the throats of the carbs they are a night & day difference in va*** pull. primarily the carb that is in front has little va***, while the back or primary(I guess) carb will try to **** the skin right off yer hand. I know that this should be better with the use on of the Uni-Syn, but should I notice that much of a difference??? Thanks again for the help, I would be screwed without all the help!!!!
No, not related. Not surprised there is a big difference before using the Unisyn. Your carbs right now have one carb ****erfly open more at idle than the other...that's all. Dail it in at idle, chasing both idle STOP screws while trying to get at the correct idle speed. It takes a bit of trial and error to have the same Unisyn float level, and still be at perfect idle speed. This is done with linkage off. Then set your high speed Unisyn with linkage on. Reset the Unisyn adjuster to allow that higher flow. Try to get it right at normal cruise speed. Quite simple to do all this, but takes some time.
I scanned the instructions and posted them here http://www.jalopyjournal.com/forum/showthread.php?t=3448&highlight=uni+syn
when i used mine, it choked off the carbs even with the thumbwheel open all the way. Even tried it on a stock 125 honda motorcycle and it tried killing that motor too. It does say Heco en China on it, so that might be the problem
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