Just the Tip

EDITOR NOTE: This is a reprint of a series entitled Just the Tip authored by Thomas Brobst. His ‘make-do-with-what-you-got’ and ingenuity makes for interesting reading and maybe help a poor soul out of a perplexing repair. See if you agree with me this is fun reading.

Just the Tip
Tip #13

Greetings, mates! And welcome to the next regular installment of
JUST….THE….TIP….TIP….TIP….TIP….TIP. (That was an echo, in typeface, in case you missed it.)

Uni-Syn carburetor synchronizer.

This tip involves synchronizing the carbs on my MGA.
Now, I suspect most of you LBC owners know all about carburetor sync’ing so that’s not what I’m planning on discussing. For those of you who aren’t well versed in the subject all you need to know is that it’s important that the airflow thru each of the dual carburetors is the same...balanced, if you will. Synchronized!

Although this can be done by listening to the air flow at the carb intake throat thru a rubber hose a more accurate method involves using a tool appropriately called a carburetor synchronizer. It’s based on the manometric principle invented (discovered?) by the German scientist and inventor Otto von Guericke in 1661 and/or the Bernoulli principle developed by Swiss physicist Daniel Bernoulli in 1738 (Thank you Google).

There are several types, I happen to have two. The British kind and the German kind. The British kind, called a Uni-Syn, (I actually have no idea where it was made, I only know of it because of my British car) sports a flat disc with a rubber seal that fits on top of the intake throat of the carb and indicates the air flow rate by how far a little red ball levitates up a graduated glass tube. The German kind (actually made in Germany) has a tapered rubber proboscis that actually fits into the intake throat of the carb and indicates the air flow rate via a moving indicator on a cylindrical graduated scale. Both do the same thing but the latter style doesn’t restrict the airflow as much so I prefer it.

German carburetor synchronizer.

You see, my MGA has a larger MGB motor but still uses the smaller MGA carbs. Hence, it seems to be more sensitive to airflow restriction. The British style tool has a little wheel with nubs on it that you turn to bias it’s venturi to bias the levitating ball to a nominal center position. When I adjust the wheel for optimum ball height the RPMs of the engine drop. If I open the wheel up enough to not lower the engine speed then the ball doesn’t float. Bollocks!!

No such problem with the German type. However...and here’s the nut of this article…. I can’t fit the German tool between the carb and the bonnet cowl on my car! So, I have two tools and can’t use either! What to do? I guess I could resort to the rubber hose method, but that’s too easy, not to mention inaccurate.

So ...I made a remote adapter out of some PVC pipe I had laying around the garage. Just a short length of tube and an elbow and, Voila!, remote carb sync’ing nirvana. (Or is it quantum entanglement? I always get those confused). I stick the elbow on the carb and the synchronizer on the other end. The tool fits into the congested space and allows me to angle it so I have the best view of the scale on the tool not to mention it’s easier on my back. haha! I applied a thin bead of RTV silicone around the edge of the elbow so it seals better on the face of the carb throat. With sync’d carbs my little baby idles more smoothly and has more get-up and go!

(Continued on page 19)