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MG MGA - P.S.W. Balancing tool for SU's

I'm not sure if this is the correct name for the tool, but has anyone had experience with the type of carb balancing tool that sits in the oil dashpots? I've heard they work well, and you don't need to remove the air cleaners, a big plus.

I checked the archives on this but didn't find anything.

- Ken
Ken Doris

Ken - The PSW tool works well for balancing the carbs if it is set up correctly. One has to put the tubes in the dash pots and get the rods set for equal heigth as well as close enough together (but not touching) to make a good comparison when the engine is running. Additionally, under certain conditions, the rods can vibrate considerably while the engine is running. I use them occasionally for a quick check, if I suspect the carbs are not right or the piston in one is sticking, but when I do a tune up I use a Unisyn for balancing the carbs. Cheers - Dave
David DuBois

Ken. I started out using a Unisyn device some 35 years ago and quickly abandoned it in favor of the German tool which consists of the tube to fit inside the piston and a wire for each tube to make a visual comparison of the rise of both pistons through.

One removes the hex nut and dampener from the carb. Installs the tube inside the hollow portion of the piston. Does the same to the other carb. Installs the wires into the hollow tubes and bends them so they are exactly the same height. I have found that this system works best for me, allowing easier set up, initial balance and a quick check to see if the carb linkage is adjusted so the carbs are synced together (you watch the wires rise at exactly the same time to exactly the same height--if not, there is an adjustment problem with the linkage).

I threw my Unisyn in the trash some 15 years ago as it was old and no longer worked properly (even though it had only been used a few times, many years ago). I still have the German SU kit that is working fine after something over 35 years. Yes, for my money, it is an excellent investment for both the short and long term. I keep a second kit in the car's tool box when travelling. Very rugged and, for me, it has worked well.

Les
Les Bengtson

If you have half a musical ear, the carbs are very easy to balance. Use a piece of plastic tubing with one end stuck into your ear and the other switching between the carb throats. Loosen the shaft coupling, and adjust the idle screws individually at the lowest possible idle speed. When the note you hear is the same in both carbs, they are balanced. Retighten the coupling shaft linkage screws, then adjust the idle speed again. This is also a great deal cheaper than other tools, and you only have four small botls to remove from the tops of the air filters (a three minute job with a 1/4 drive ratchet)

I now use this trick only on friends' cars, as I now have a single Holley mounted, which just has a mixture screw and an idle screw, nothing else. It has always entertained them the first time.
dominic clancy

Dom - Unfortunately I have what must be the absolute opposite of "perfect pitch" - can't tell one note from another, so the listening approach is probably not for me :(

Les - is the tool you mention a PSW? Is there any identification I it I can use to look it up on the web?

- Ken
Ken Doris

Ken,
I have a PSW tool set. It appears to be what Les described and was made in West Germany. Bought it years ago. It comes in a small pouch with intructions on which it simply says "Instuctions for the PSW Tool". There is a stylized PSW logo, but no address or number. Can't remember where I bought it. In addition to balancing the carbs, it comes with a jet centering tool, a jet adjusting wrench and a fuel height setting tool.

Regards,
GTF
G T Foster

Ken,
A quick check of the Moss web site shows SU Tool Kit (386-300), the illustration for which appears remarkably similar to the PSW tool kit.

Regards,
GTF
G T Foster

The other thing the SU tool kit/PSW kit does is allow you to see the progress of your air pistons in a continuous manner from dead stop idle (where most folks set balance with a UniSyn tool or a hose) on up the rpm range (where it becomes more tedious to use the UniSyn to gauge the progress of the air pistons up the range).

The reason this matters at all is that when you balance your carbs at idle only, you may not actually retain that balance once the throttles move up off their stops. Sometimes, there is enough slop in the throttle linkage from age and wear, such that the linkages slip or shift into a different position in relation to each other once the throttle cable is yanked by the pedal, and then, suddenly, what was once balanced at idle turns out to be somewhat out of balance the rest of the way up the rpm range.

Admittedly, the wear has to be reasonably significant, but it is not all that unusual, and to be able to visualize this jump from balance to imbalance, the SU tool kit set of pointer wires and other widgets simply makes it easier to see this dynamic change as it happens. It may point to your need to replace your linkage even when your static inspection may lead you to think everything is OK.
Bob Muenchausen

OK, I'm convinced it's worth buying. Using the number GTF supplied, I just ordered one from Jeff Zorn (LBCarCo.com). Discounted from Moss's price, I paid $20.36. I'll let you all know how it works out once I receive it.

Of course, that's assuming I can get the car started, seeing how the temp here has been in the teens for the past two days. It was 55 on Saturday when I installed my newly rebuilt carbs and took the car out for a test ride. Felt like spring, but now it's definitely deep winter again ;~(

Thanks for all your inputs.

- Ken
Ken Doris

Ken. One of the two tools I have is marked PSW, the other one is not. Both list the same stock number. I assume that the tool marked PSW, on the instuctions, is the newer one and that PSW purchased the manufacturing rights from the original maker. In any event, it is a fine addition to anyone's tool box and you should be quite happy with it.

Les
Les Bengtson

One bit of suggestion from years of using this product. When you line up your two wire indicators, note what is also in the very same line of sight with them when they appear to be exactly in line with each other (appearing as one wire, tho one is in front of the other). That third point, farther away but along the same sight line will help you get your head and eye near the right position for viewing once the engine comes to life and things start to shift.
Bob Muenchausen

Anyone had any experience with the "colour tune" system? Sounds logical to compair burn flame.
robert maupin

Colortune is not a bad idea, it doesn't seem to work as well with today's gas as it did years ago with the sorts of "gasoline" we had when it first came out in the late 60's. Not sure why, but it seems easier today overshoot the mixture in either direction than before, even tho all the engine mechanicals and electricals are essentially the same as they were back then. At least, that has been my luck.
Bob Muenchausen

This thread was discussed between 15/01/2006 and 17/01/2006

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