Topic: Homemade Carb Sync Tool

[billstron]

Hello,
I believe I am in need of a carb sync, and I, being a tight ass, don't really want to spend >$100 on the morgan tool.  When building a homemade gauge set, do you follow the directions in the Clymer manual?  Further, when using it, where do you hook it up to the carbs?  It seems like a lot of trouble, etc to hook it up at the inlet with a restrictor plate like the manual says. 

Thanks,
Bill

[OldSchool_IsCool]

Bill,

The thread below has pics of a homemade carb sync tool I built for under $5 so far.  I say so far as I haven't yet aquired the fittings for the vacuum ports.  I'm thinking I might be able to make some fittings from plastic or rubber parts if I can't find some that are actually made for the job.  The key is that it can't leak ANYWHERE!  The idea of this tool is that the 4 carbs will pull against each other with the strongest pulling the dyed water up it's tube the most.  One only needs to dial in the adjustments until the fluid level is even in all tubes (each carb sucking just as hard as the others).

Here is the thread:

http://www.sohc4.us/forums/index.php?topic=10891.0

[jdamman]

The fittings to thread into the carbs can be made from brake line (don't remember what size, 3/16??) and using a M5X.8 die to thread the ends.  Don't thread too far, and the taper in the die will make a tapered thread to seal up the connection at the carbs.  Using this and a multiple valve system from a fish tank (bought at pet store) a vaccum gague and a large fuel filter in line to dampen the vaccum reading, I was able to sync my carbs for under $20 (already had the vac gauge).  The other thing I did was when I thought I had each one pretty close by itself, I then opened up all of them one at a time untill I had them all open and each time, I watched for the needle on the vaccum gauge to move.

[upperlake04]

Old School - Intrigued with your design and can't see why it wouldn't indicate vacuum differentials. You will be a famous man iif it works well    The vacuum port adapters  can be  home-built from an M5 bolt, steel tube, brazed and (carefuly) drilled lengthways. Maybe even epoxy glue and electrical tape first to test the principle...  go man go 

[billstron]

The idea of this tool is that the 4 carbs will pull against each other with the strongest pulling the dyed water up it's tube the most. 

With this method, is there much concern about sucking water into the carb?  Intuitively, I feel like the hoses should be long, and a large volume of water should be used. I definitly like the idea, though.   When are you planning on finishing it? 

Bill

[OldSchool_IsCool]

Upper,

I like it!  I don't have welding/braising capabilities so maybe an epoxy fixed bolt/tube will work.


Bill,

As I haven't yet tried the tool, I just don't know how big a risk water ingestion would be.  It stands to reason that if one carb is pulling way more then the others that it could very well pull water into itself.  It's vacuum would have to differ from the others by several PSI, I would imagine.   I'm hoping that the extra length of the tubes would help to prevent ingestion in all but the most severe cases of imbalance.  Perhaps putting a micro valve (the flow control kit has those too) on each tube would allow one to slowly open each tube and thus head off the possibility of a carb sucking up all the juice.  That would mean more joints and more opportunities for leaks though.


JD,

I also like the inclusion of at least one vacuum gage.  That way, absolute pressure could be measured and one could collect trend data as the engine ages.  Maybe the in-line fuel filter would also give the operator time to kill the engine before water ingestion.

[upperlake04]

how about dark blue two-stroke oil insead of water?

[OldSchool_IsCool]

Upper,

That may help.  I would think that heavier weight would add a gravitational component to help mitigate an imbalance.  Kinda the idea of the mercury-type balance tools.  Also, a (much?) higher viscosity liquid would slow the travel of the liquid to the carb giving one time to react.

A thought I had on the valve idea would be to use hemostat-type clamps to pinch off each tube.  That would allow a slow introduction of each tube to the pressure mix without risking additional leaks.  A significant leak would pretty much guarantee ingestion!  Hemostats can be pricey though.

I'll definitely keep y'all posted once I get decent fittings for the vacuum ports and actually try 'er out!

[billstron]

OldSchool,
Let me know, I think I'm going to try to make something within the next week or so. 

Bill