Carburetor Syncronizers?

[pdplot]

Have a UniSyn. Had it for years. Used it once. Now use a stethoscope or my ears. I also disconnect the linkage. Synchronizing the carburetors is way overdone. Let it be.

 

[CJD]

Unisyn. Is that the precision instrument with the floating ball? If so that is what I use. If I didn’t have one I’d use my ears and not worry about it...but since I have one I cannot imagine ears being as precise as a precision instrument.

 

[poolboy]

IF and that's a big 'if' there is any "precision" in the Unisyn, it's going to depend upon the user to utilize it...Set it 1/4" different over the mouth of one carb than the other will make you think the carbs are not in sync when they are ....or conversely make you think they are synchronized when they are not.
As far as not being bothered with synchronization, I guess that's fine if you're satisfied with not having the engine tuned up as best as you can. Is it as long as the engine runs don't be concerned about fine tuning the timing and mixture too, or is it just synchronization ?

 

[glemon]

IF and that's a big 'if' there is any "precision" in the Unisyn, it's going to depend upon the user to utilize it...Set it 1/4" different over the mouth of one carb than the other will make you think the carbs are not in sync when they are ....or conversely make you think they are synchronized when they are not.

Doesn't the same thing apply to the hose hiss method? I have never tried it, the main reason being I did't figure I could accurately hold a hose the same distance as well as the same angle of the hose in relation to the carb or my ear for that matter) consistently. At least with the uni-syn you place it right on the carb and can see if centered or not, and it's design will always be in the same angle from carb to carb as the airflow.

Anyway, seems to be a subject of much debate, the wire things sound interesting, but have never tried them. I guess I trust my sight to determine "sameness" from carb to carb better than my ears.

Most everybody seems to have their favorites, maybe based on what you have done forever, or what somebodys showed you, or what makes sense intuitively to you (I think that last one is part of the reason I like the uni-syn) That is fine, they are British cars, if you get it to run right the method you use works.

Have been using a uni-syn since forever, is pretty intuitive and seems to work fine.

 

[CJD]

The thingy I use completely closes off the carb mouth. All air into the carb has to go through the precision instrument. Did I mention it is very precise??

 

[Geo Hahn]

I also use the UniSyn and agree that it seems precise. I base that on the observation that the results are repeatable - i.e. I can put it to the carb, remove it and when I put it in place again I get the same result. There is no accuracy involved or needed as you are not measuring a quantity (e.g. vacuum), just a relative value.

 

[CJD]

I look at it like this...

I do my tune ups by the book, to the best of my ability and with the best tools I can beg, borrow (or steal?). If it’s worth my time to tune up the car, then it’s worth my time to do it as closely as I can get it to perfect. I can dial my car down to a reliable idle at 500 rpm...but I set 700 just to be safe in traffic. Meanwhile, I read over and over in the forums how owners can’t get their idle below 1000. You have to wonder, as I do, how many steps of their tune-ups are considered “close enough” as they are doing them. Believe it or not, all the “close enough’s” will accumulate in the end!

 

[dklawson]

... I read over and over in the forums how owners can’t get their idle below 1000. You have to wonder, as I do, how many steps of their tune-ups are considered “close enough” as they are doing them.

I do not wish to sidetrack this discussion of synchronization. However, there is at least one reason owners like me seldom get their car's idle smooth or stable at 500-600 RPM. Cams. For a couple of the engines I have rebuilt, the factory cam was not available or was only available as NOS for a much greater cost than an aftermarket performance cam. Performance cams often will not idle well below 1000 RPM depending on other aspects of the engine build.

Again, I don't wish to sidetrack the airflow discussion but there are reasons why the factory idle specs are not easily obtainable.

 

[martx-5]

I too have a performance cam, a pretty lumpy one, and have to leave the idle at about 1000 rpm. Any lower and it gets pretty ratty. To synchronize, I have both a Uni-Syn and one of the snail style types. I much prefer the snail type. Actually, the Uni-syn I have I bought when I got my first TR, a '63 TR4 back in '65. I've had to replace the rubber on the front once, as it just sort of lost all of it's spring and had trouble sealing. Although I don't use it anymore, I just can't ditch it.