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Any idea how this thing works?

https://www.ebay.com/itm/Vintage-NOS-uni-syn-Carburetor-tool-synchronizer-gm-ford-chevy-rat-rod-pontiac/192885055777?hash=item2ce8d86121:g:~mYAAOSwJcdcq-8y

Measure Vacuum ???????????

How did they work, you ask?

Not very well would be my answer! Used them without much noteworthy success many times as a kid.

What was it designed to do ?

I still have one. Bought it when I had an old MG-A and had to sync the carbs. A bit tricky but once you get the hang of it, they work pretty good. It is nothing but a basic device to make sure you have equal air flow through the carbs.

I had an old MG-A and had to sync the carbs.

WOW !!!!!!!!!!! U sync the carbs on a MGA. YOUR GOOD !!!!

Barry (Packardbarry), to return to the main street, please find attached the ->operating instructions.


Copied from the web: "This carb synchronizer works on downdraft or side-draft carbs with neck sizes as small as 1-3/8" to as large as 3". Edelbrock sells a smaller "motorcycle" version for smaller carb necks."

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I had one and used it to balance the carbs on my '73 Datsun 240Z. Simple way to balance the air flow. One would place the device over the throat of the carb and note the location of the indicator while adjusting the idle mixture and speed. Then do the same on the other carb. Repeat until all carbs are the same. I guess it could be used in a single carb engine, adjusting for the best reading.

Wow, seems like everyone else had good experiences with it.

These are only needed if you have a multi carb setup, AND each carb fuels different cylinders. My porsche has 2 two bbl carbs, and each barrel feeds 1 cylinder. You have to balance airflow to each cyl so that each cyl is making the same amount of power. If the carbs are not in sync, the engine runs poorly and will vibrate and rock alot.
I can't imagine a need for this on any packard, unless it is a hotrod with multi carbs. Muti carbs are a big pain in the "you know what" but if synced properly very nice. Syncing is a lot of work. Tuning a 2bbl or even bbl on a packard with a vacuum gauge is much easier.

I have an inches of water gauge which can be lowered into the throat of each barrel to compare airflow.

However, to get things right first do a compression test, then a running compression test, and then check valve lash.

After that pieces of brazing rod can be used to set the throttles to exactly the same setting. Once that is done and the idle screws are set to the same setting the gauge can be used.

On the SU (Skinner Union) and Zenith side draft carbs the main jets can be sychronized using a dial indicator.

The last step is to find well to do customers who like to spend money. I found most people with money treated mechanics the same way they treat people at work - rotten.

It's so much nicer working in the professional environment. I see our clients closing down plants and it makes me sad because they are good people