synchronize carburetors

[red_dog007]

Well in my 240z, the biggest and most important thing that I gotta do under the hood is synchronize my carbs. The engine still runs, but of course doesnt run as good as it can.

Over at BlackDragonAuto I found a synchronizor tool for $30 I think. Is this a tool that I could use? I know nothing about how to do this and my brother who has even rebuilt his own carb doesnt know how to do this.

Is this a tool that basically dummies can use to get everything running correctly?

[MikeW]

The Uni-syn tool simply provides a way of making sure that the amount of air flowing into each carb is the same. It's got a little red float in a tube that rises and falls with the airflow. You adjust the tool to the point where the indicator is somewhere in the middle; it doesn't matter where. At that matters is that it's the same for each carb. You don't want to keep the tool in place for very long as it will affect the engine. Just hold it in place long enough to get a reading and alternate between the front and rear long enough to get them the same. There are plenty of online guides that explain how to tune SU carbs. There's more to it than just getting the airflow the same. One common mistake is to just jump in and start tweaking the carbs without making sure that everything else is in tune first or that you even have a problem to begin with. Bottom line: you can use the tool easily enough but be careful with what changes you actually make. Ask questions here if needed.

[John Coffey]

Forget the Uni-syn. It typically only flows enough to sync the carbs at idle. I've had great success using a Synchrometer (http://www.international-auto.com/index.cfm/fa/p/pid/2727/sc/8140) to sync the carbs at idle and at 2,500 rpm.

[ezzzzzzz]

The unisyn works fine at idle and cruising rpms. The button in the center is rotated in or out to allow for as little/much airflow as needed for adjustment at any rpm.

[SavannahZ]

Forget the Uni-syn. It typically only flows enough to sync the carbs at idle. I've had great success using a Synchrometer (http://www.international-auto.com/index.cfm/fa/p/pid/2727/sc/8140) to sync the carbs at idle and at 2,500 rpm.

I definately agree with using the synchrometer. It comes with a rubber piece that allows the tool to fit snuggly into the chamber and you can let go of the tool to make your adjustments. Works well at low and high idle. It's a little tight on the rear carb, but fits fine.

The price on that link might be daunting. I paid a couple years ago, I think, $35 for a new unit off ebay.

[Victor Laury]

One common mistake is to just jump in and start tweaking the carbs without making sure that everything else is in tune first or that you even have a problem to begin with.

Wiser advice can not be bought. Tuning the carbs is the LAST step of a complete tune up. Adjusting the carbs on a poorly adjusted engine will do very little besides just making things worse. Start at the points then timing, then plugs, then valve adjustment - Then Carbs.

My best advice?

Buy, rent, borrow or steal this video

http://www.ztherapy.com/products/videos/SUTuneUpVideo.htm