Unisyn for Synching Carbs

[RJ]

Anyone use a Unisyn to synch their carbs? I used a mercury setup once to sycnch my carbs but the stuff bounced around so much, and I couldn't blip the throttle while I had the thing hooked up so I can't say for sure if I really had them adjusted properly. I have a Unisyn that I used on my old 240Z which worked great but that's only 2 carbs. I'm cheap and don't want to buy a set of gauges. Any ideas?

[Nessism]

I don't think it's sensitive enough to do a good job. Mercury gauges work pretty well but as you noted, they do move around a lot. There are supposed to be small restrictor plug in the lines which do help some. Maybe your set was/is missing these?

[Muser3]

carbs

RJ,
I am sending you this link to a cool tool for balancing the carbs. It only does two at a time but they are compared to each other and they are truly in balance. I use it all the time on my boxers, one of which is a four cylinder.
On the inline four I balance 3 and 4, then 3 and 1, then3 and 2. I honestly wouldn't use anything else. if you are interested in the "nuts and Bolts" of it, post a reply and I'll explain how I make it work for me. Look it over!

http://www.powerchutes.com/manometer.asp

Lee :-D

[Steve]

That is a decent meter for balancing two carbs, but all it takes is one use of a gauge set that watches all four cylinders to convince you. :shock:

Adjusting one carb has an effect on all the others, and that just can not be seen by watching two at a time.


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[posplayr]

Those Powermeter Manometers

are so cheap why not just buy two and see all 4 carbs at once. I used to have a set of "carb sticks" with mercury and they seemed to work great unless you reved the engine. I dont remember exactly but the mercury went flying. I also used a Unisync for dual SU's on a 69 2000 Datsun Roadster. With 4 barrel Solex the carb sticks (4 columns) were better. After losing a large part of my mercury I did end up just buying two separate pressure gauges and using a large baffle to slow down the intake pulses. guess a restrictor would do the same.

Posplayr

[Muser3]

gauges?

I set them up at idle first, then again at 4k or about there.
I have a set of mercury sticks too. Not to argue but to state my thoughts, I used them at first on my GL1000 because I thought I had to have them. I have not used them on the GS11E because I like the way it performs otherwise.
Kindest Regards,
Lee :-D

[RJ]

Thanks for all of the replies guys. Muser3 I'm definitely interested in the "nuts and bolts" deal. Go ahead and write it up when you get a chance. Thanks.

[Muser3]

nuts and bolts

First you have to make the adapters to go into the vacuum ports in the head. I think they are 4mm. May be 5. Anyway, get some philips head screws of the correct size and about an inch long. Get the nuts to fit also. I used my HF 6" drill press to drill four of these lengthwise with a 1/8 inch drill. (having the philips head helps to center the drill) It also helps if you have a vise for the dill press. When the holes are drilled, cut the heads off and push about 1/4 inch of the cut end into a 4 inch length of 1/4 inch vinyl tubing. then screw the nuts on right up to the tubing follow it with a small o-ring. I then put a small cable tie very tightly on the tubing over the threads of the screw. In the other end of the 4 inch vinyl tube slip a 3/4 inch or so piece of plastic tubing about half way and secure it with a cable tie. Next, cut four one inch pieces of vinyl tubing and melt one end with a lighter and gently pinch it together with pliers. You now have four adapter tubes and covers for the ends of each. Since you will use two at a time it is easiest to get all four in place before heating up the engine. HAPPY NEW YEAR!!! \\/\\/\\/ I use atf in the tubing for the manometer because it's red and easy to see. the website pretty well describes how it is put together.

[Jd Powell]

I highly recomend the morgan carbtune. Far superior to both guages and merc sticks. Do a search on it , and you will see that many others feel the same way.

[renobruce]

I highly recomend the morgan carbtune. Far superior to both guages and merc sticks. Do a search on it , and you will see that many others feel the same way.

You might be able to synch two at a time fairly well with CV carbs (all get synched to #3), but I wouldn't reccomend it with VM carbs. Change one and they can all change... somtimes alot.

The Morgan carbtune is far superior than anything out there IMO. It is awesome.

[Steve]

Weel, now I see another reason not to use this method:

Since you will use two at a time it is easiest to get all four in place before heating up the engine.

Any book I have seen that covers carb balancing states that it is to be done "when the engine is at full, operating temperature." :shock:

Some day I hope to experience a Morgan Carbtune to see if it is really good enough to convince me to hang up my 6-column mercury sticks for the last time.


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[Muser3]

nuts and bolts

Well Steve, I guess i just didn't communicate effectively. You put the adapters in place, then warm up the engine, then you attach the manometer to the adapters after the engine is up to temp, then you balance. By the way, you can use these adapters with almost any system.
I find it easier to get any balance/sync contraptions attached to the head prior to bringing it up to temp. (I put caps on the carb stix adapters before I used it too.)
I may be wrong here, but I think that when you change one butterfly, you change the engine's performance. The other carbs will not change until you change them.
Happy New Year guys, and RJ I hope I haven't monopolized your thread.

[paco13]

Another Morgan Carbtune supporter here, mine works great.