Hot Rods Using a Uni-syn carb. syncronizer

I have a pair of Speedway super 97's on my flathead. they seem to run OK but I want to syncronize them. When I put the uni-syn on one of the carb with the center part screwed wide open the motor starts to choke and stall. It sounds like I'm choking off all the air. Do I need to open the throttle plates more or turn the idle adjustment screws in to lean the idle mixture down. I've read the instructions but they don't seem to help

 

Does it do that on both carburetors?

 

That's baffling. I just pulled out the ol' Uni-syn and opened it up as you say you did. There is clearly more airflow capability than what a carb with closed throttle blades would require. It made me wonder if setting the Uni-syn in place covered an air bleed or bowl vent causing it to stop the fuel flow. But looking at the pictures of your carb, there doesn't seem to be anything that the Uni-syn would cover. Are the mixture adjustment screws on that carb adjusted in or out a lot more than the other carb?
P.S. I'm no Stromberg expert but I love a good automotive mystery

 

Does not take much to choke out a 97, speedway or stomberg. Running 3 on a 355" mild built sbc. Took a re-jetting on main and idle, as well as stacked air filters to keep it idling proper. One air cleaner limits the flow enough, she won't idle right, no air cleaner it was lean, two seem to work well.
I gave up on the sync tool on my son's triple webbers, we use a laser thermometer on the header pipes to get them right.

 

My experiences with a uni-syn has been that you only put it over the carburetor for a 1/2 to 1 second.
You adjust it to show some flow, [if you leave it on any longer it can choke the carb down] then work back and forth on the carburetors to dial them in.

 

Sounds odd to me. I've used them a fair amount over many years, and yes, even on 97's (original ones), Rochester's also tuning a Man-a-Fre.
You can leave them as long as you like as long as you are just testing at or near idle speed.

See bchctybob's comments.

Mike

 

This is the only type I use anymore. My uni sync collects dust.

 

Oh joy, post it and don’t tell anyone what it is or how it works.

 

I use one on my dual quads and it's been perfect for yrs. A friend uses his on 97's and doesn't have your problem..

 

I used my Uni-syn on my roadster (292 sbc w/3 Strombergs) with good results and no problems. Lately, I use it on my wife's Corvair with mixed results. Several of the Corvair club guys recommended the type of synchronizer shown above and one uses a Magnehelic differential gauge hooked to the vacuum port. Both are available on epay, prices vary. Used properly, the Uni-syn shouldn't cause it to die during adjustments unless your engine has a really big cam, heads, etc. There's something else going on there. We need some wisdom from Carbking and Squirrel.


Sent from my iPhone using The H.A.M.B. mobile app

 

I got a guy that can fix carbs!

 

I agree with Mike. You simply adjust the flow rate on synchronizer.
Another note.
You must unhook the linkages to both carbs. Set them evenly pulling the same amount of air, then adjust the linkage to keep the carbs pulling the same. Fuel/air adjustment screws are used only for fine adjustment.
They will not allow you to get the carbs close initially.

 

I will be watching this one. I just boought a Uni Syn for my 348 three deuce. Never had a need before.

 

The throttle linkage on your 348 is not progressive?

 

Ok, adjust the intake a 1/4 turn to the right, then open the jets a tad and we’re good.


Sent from my iPhone using The H.A.M.B. mobile app

 

This is the one I also use when I set up my flatty ,
Just to Balance Carbs , then I use a wide band 02 for all other turning, plug reading is long gone with gas off pump ,( modern gas )
Another note on 2 or 3 97s /stombergs carb set up ,
Motor that makes 300hp & up , they are just for looks ,not enough CFMs , switch to R2Gs , you will be much happer

 

I even modified a velocity stack with a lid that has a hole and an adjustable"vent" so I can use it on most carbs, even 4 barrels.

 

Some carbs require a spacer to get Uni-syn above carb body. Example

 

My ear is my Unisyn.

 

It works just like a uni sync, only better. Figured with the thread being what it is, most could figure it out.

Basically goes on top of your carb and as air flow goes through it, the needle moves to tell you how much. I bought mine 20-25 years ago at Karls VW in Mesa, AZ. Just google uni sync or carburetor synchronizing tool, and the world is yours