Uni-Syn carb synchronizer #2

Tom's36coupe

Tom's36coupe

Well-known member
Was playing around with this Uni-syn thing today and noticed when I put it on top of the front carb , closest to the radiator it did not do anything, then I put it on the back carb and the engine slowed down and quit. Restarted and noticed the back carb is pulling much more air than the front, put my hand over the front and hardly made a rpm change, on the back it sucked my hand down. Have the idle screws adjusted the same, where do I go from here to make them the same?:confused:
 
Also having trouble keeping my idle speed the same. Have it around 700 and then drive the car and it creeps up to about 1200, adjust the idle screws and its back then go for another drive and back up it goes. Could it be a vacuum leak somewhere?
 
OK , let me try to explain .......... without seeing your linkage makes it a lil harder .Disconect linkage between the 2 carbs , be sure that there is a return spring holding both carbs closed , start angine , (I dont use a unisinc , I used a piece of heater hose & listen to the cab thru the choke horn) works just as good as a unisinc, now using unisinc set both carbs so they are pulling the same & your idle is set at the speed you like .Fine tune idle mixture screws at the same time , they should be around 3/4 to 1 !/4 turns out , NO more ! Once you get this set , now reconnect carbe together making sure both carbs are still pulling equal , the linkage should be very neutral .It the carbs change , "DONT" addust carbs adjust linkage connectint them together ! Its realy very easy & quick . I hope this helps
Cheers
Tony
ps I would block off all vacume ports & then after carbs are set reconect them & make sure you have no leaks!
 
Thanks Tony for the advice, will give it a try today. The back carb is connected to the gas pedal and I have a spring pulling on it for tension. The front carb is just connected to the back by way of a link, if I start the engine how will that work on the front with no spring.
 

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Tom like I said be sure to have a spring hooked to both carbs ! Just hook a temporary spring to the front carb & turn engine off when you hook up the linkage .re-adjusting the linkage as a very importantant part of this process so that both carbs open at the exact same time , but if you do it as I sugest & make the linkage on the tight side but both carbs still pulling the same amount of air you should get it perfect !
Cheers
Tony
 
Any suggestions on how or where to hook a spring to the front carb? As you can see in the picture I have the carbs hooked together on the driver side and the spring on the passenger side. Sorry to be a dummy on this!:o
 
just hook it to the carb ball where you take the linkage to the rear carb off . Any light spring will work , u may need to use a peice of wire to connect to the spring 7 attach temporarily to something on the engine .Be sure you are pulling it closed not open .
 
Tom the idle stop screws are what will change the idle speed & the air flow on the inisinc get the speed where you want it with the same fow on the unisinc on both , then slowly 1 by 1 turn in idle mixture till engine runs a lil rough & back out about a 1/4 turn or till engine is smooth . Now if this has sped your idle up thats good but reset idle speed recheck unisinc. keep going thru this proceedure until you get it as good as you can & then reconnect carbs .
If you get in any trouble it may be easier to call me . But once you get going I think you will find it very easy .
Cheers
Tony
to answer your Q dont udjust screws untill you start it & set unisinc
 
If it's not a progressive linkage setup, only one idle speed screw is necessary. The other can be backed out or removed. Adjust the conmnection linkage. Theoretically, the rod should be adjusted to hold both carbs wide open with no bind or slop, then adjust idle speed and fine tune idle mix. JMO
 
Just a quick "plug" for the Uni-Syn.....I used one with great results setting up my son's mechanical Hilborn for the street. The Hilborn is modified quite a bit, but the Uni-Syn was an invaluable tool to get each cylinder in balance. I agrre with KiWi that a tube can be used to hear the flow differentials, but since you have the tool it will be very reliable.......
 
Did some playing today with the carbs and linkage, the back carb that was pulling more air had the idle screw turned in almost 2 more turns than the front. Adjusted both the same and started over, it was close but then the front carb was pulling more air, did some more and they are both real close now. Interesting now with them about the same my motor seems much stronger, really was reving good. Must have been way off before, can't believe I did not notice before, dumb me!:o
 
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