Carb Sync Gauges

[HotRod]

  I want to build my own set of carb sync gauge manifold, what kind or brand gauges should I look for and where can I get just the gauges?

[gordonv]

Should be able to get at most auto stores. Price whys, try Harbor Frieght. I think as long as you get 6 of the same at the same time, you should be OK.

Or us 2 gauges. One for #3, and a manifold for the other 5 carbs using one gauge and shut off valves.

[Bobbo]

You also might want to get oil filled (dampened) gauges.  Some have even placed small tubes inside the vacuum hose to act as an orifice to further dampen the pulsation.

[HotRod]

You also might want to get oil filled (dampened) gauges.  Some have even placed small tubes inside the vacuum hose to act as an orifice to further dampen the pulsation.

Where would I find those type?

[Ken Tarver]

here's mine ~ gauges from Harbor Freight (not liquid filled), I have the fish tank valves on each tube. Bought 6 gauges, 1 did not match the other 5 so took it back and swapped out, about $13 each.

Ken

[fordmano]

Paging Ricky-D to the White courtesy phone,,,, Ricky-D to the white courtesy phone please.

You can check out what Ricky did or you can go and look at my Multi point upgrade thread, I am on my iPhone right now and don't have the link for the guages handy but they are NoShock gauges bought on E-bay for less than $3 a piece I think, I bought 7 in case one was way off from th other cheaper than paying shipping twice to return one.

Send me a PM if you want more details I will check back and see how your comming along with this when I get to the office tonight.

[fordmano]

You can if you really want to make it nice use automotive or aircraft gauges that are liquid filled propably something like Stewart Warner or Sun gauges or a dozen other companies that sell dash mounted gauges will probably have some but be warned the fluid filled will be much more expensive but look better and easier to use in my opinion and I am too poor to put out that kinda money.

If your feeling overly wealthy let me know and I will make a set you can brag about to any owner of a  Multi-carbed machine.

Just saying.

[Ken Tarver]

dam wish i had know about those noshok gauges

[fordmano]

dam wish i had know about those noshok gauges

You live you learn, and with all the knowledgable others around here it helps in that learning curve. Well it has helped me a bit, Ok it's helped me a lot.

[HotRod]

here's mine ~ gauges from Harbor Freight (not liquid filled), I have the fish tank valves on each tube. Bought 6 gauges, 1 did not match the other 5 so took it back and swapped out, about $13 each.

Ken

Thank you Ken,very helpful.

[HotRod]

Paging Ricky-D to the White courtesy phone,,,, Ricky-D to the white courtesy phone please.

You can check out what Ricky did or you can go and look at my Multi point upgrade thread, I am on my iPhone right now and don't have the link for the guages handy but they are NoShock gauges bought on E-bay for less than $3 a piece I think, I bought 7 in case one was way off from th other cheaper than paying shipping twice to return one.

Send me a PM if you want more details I will check back and see how your comming along with this when I get to the office tonight.

Thanks< I realy appreciate it,I was at work all night so i could'nt respond.

[Foozle]

dam wish i had know about those noshok gauges

My personal experience with the ultra cheapo NoShok gauges is that you'll need twice as many (12) to get six that read the same - negating the fact that they're "half-price." If I had it to do over again, I'd spend a little more and be done with the hassle.  Granted, you don't need $25 oil-filled gauges to do the job, but this is a case where you get what you pay for.  As always, YMMV.  Terry

[SCain]

Hotrod, I went to my local HVAC Supply and bought 6 Vacuum liquid filled guages for about $125.

[Ken Tarver]

i did look at some cheap ones at Granger, but they were like 1 1/2" dia., the ones i got are 4" so they are easy to see for old eyes

[Patrick]

I know that I'm the only one, but, I use one ole plain vanilla vacuum gauge. Simple, quick and best of all, it works well..

[HotRod]

  Thank you gentlemen,I just love the knowledge on this board. I feel confident I can build a beautiful set of quality gauges now,I'm grateful.

[fordmano]

My personal experience with the ultra cheapo NoShok gauges is that you'll need twice as many (12) to get six that read the same - negating the fact that they're "half-price." If I had it to do over again, I'd spend a little more and be done with the hassle.  Granted, you don't need $25 oil-filled gauges to do the job, but this is a case where you get what you pay for.  As always, YMMV.  Terry

Well I guess I got lucky beyond all possible belief??? I purchased 7 and they are almost all identical and using your thinking is why I picked up seven in the hopes only one would be too far off to use...

You are correct normally the cheaper they are the cheaper they probably are and your more likely to get a fare percentage that will be bad or too far off from the others to be of any use.

[fordmano]

Hotrod, I went to my local HVAC Supply and bought 6 Vacuum liquid filled guages for about $125.

Well I don't happen to have the link right now since I am currently on my iPhone sorry, but I did some digging around and found some liquid filled gauges at Jegs they are in Chrome or Black and 2-1/4" if memory serves me  they are $19.99 for Chrome and $18.99 for the Black. I also found some that are 2-1/2" for $10.00 each at an online HVAC supplier. 

So they can be found for most budgets, I will admit one tuff thing is to find then with larger faces and liquid filled for less than $20-$30 each gauge.

I also found digital readout gauges that are extremely easy to read and are super accurate "BUT" they are Very pricey, around $130 each,,,, WOW!!! Well they are impressive.

[fordmano]

I know that I'm the only one, but, I use one ole plain vanilla vacuum gauge. Simple, quick and best of all, it works well..

Well sir, my hat is off to you. If your Valk runs they way you like it then that is fantastic and you are an amazing mechanical wizard, getting 6 CARBS to pull the same vacuum is a tuff task and being able to se how a 32nd turn of one single carb screw effects all the others,,, wow just wow.

Side note have you ever had the opportunity to compare what all 6 look like on a full set of 6 gauges? That would be interesting to most of us.

[Ken Tarver]

fordmano ~ your last post; are you commenting on the correct previous post? i'm thinking you copied to wrong one to you last post?

Ken

[fordmano]

fordmano ~ your last post; are you commenting on the correct previous post? i'm thinking you copied to wrong one to you last post?

Ken

Awe yes you saw that, yes It was a mistake I was working from my iPhone and managed to just get the quotes fooled up a bit.

I fixed it now I think, now that I am at work and have time to surf the interWEBZ on a real computer.

Ok here is to all of you,, , keep your eyes on me since I regularly make mistakes and speak out of turn and on the wrong subject or some other type of goof up. And my typing and grammer SUCK big time.

(glad to see your on your toes there Ken)

[Ken Tarver]

   it's ok, hooha.......it surely doesn't top some of my goofs, they come around pretty regular for me, seemingly as I get older for some unknown reason

[bigfish_Oh]

I ordered a set of 6 mercury tubes in 1988 for my '82 CBX. I never saw a Honda dealer with 6 tubes back then. I traded them off to brother, I'll be borrowing them back this spring, he probably won't sell them back!!

It was amazing the difference after adjusting valves and rebuilding/syncing carbs, if you did not watch tach, you would not believe the bike was idling.

 

[Chrisj CMA]

I guess I am slow.  Im reading this not really understanding why any of you would even want six guages.  I have seen people use the "twin Max" I believe that is what its called....its a different sort of guage...digital I think but the principle is this.  CHECK the vacuumm on #3.  Then using the SAME GUAGE go from cylinder to cylinder setting them to the SAME value that #3 was.  That way no matter how accurate (or inaccurate) the guage is the error is constant and each cylinder is the same.  Now with the twin max I believe it stays connected to #3 the entire time and the second hose travels to the other five one by one and you MATCH values.  If that is important  then you can get TWO guages and try to make sure they are identical.  That would be MUCH easier than trying to get 6 or 7 indentical...maybe someone will chime in and enlighten be as to why my logic is wrong, I dont pretend to be an expert.....120K and mine have never been sync'ed......runs perfect so I have never done it

[Patrick]

There was a post similar to this one when this one was first started and I explained how I do it in that post as I've explained it over the past 12 years.. Basically I agree with Chris.. A single gauge works just fine and each cylinder can easily to set to within one needle width which is about .5 in/hg.. Honda's spec is 1.6 in/hg and I've not seen one get that far out of adjustment unless someone who didn't know what they were doing tried it.. That said, it is fairly easy for someone to forget to shut off #3 while adjusting another so things can get screwed up pretty quickly if that happens.. Its not a hard fix though..

[FLATSIX]

Chris and Patrick,

When I do the sync. then I see that each time I touch 1 carb to adjust, I see others changing too.

Even the #3 changes when I make adjustments to the others.

That is the raison that I work with 6 lines instead of 2 or 4. I want to see them all 6 and even then it is not so easy to get them all at +/- the same level.

I find the system of TWINMAX very cool, but not for our FAT LADIES as the carbs have a connection between them all and they influence each other.

I stick with my handmade - tool !

[Quicksilver]

Just checking what range do you need on the gauge to have it work. Is it say 1 to 6 inches of mercury with increments of .1 in between to set them at 1.6? I've never looked at one.

[Patrick]

Any gauge within the 5-15" or so range will work.. Each engine will pull differing amounts of vacuum, it appears that there is a difference in the vacuum between CA and 49 state engines due to difference in valve timing between the two engines.. Idle RPMs will also make a difference as well as individual engines .. As long as you set them close to each other the ' nickel trick ' works.. Honda specs are pretty far from each other [1.6"] so this is not a real big deal of an adjustment, all you're doing is setting slide/plate height and I'm happy within .5"..

[Madmike]

Just checking what range do you need on the gauge to have it work. Is it say 1 to 6 inches of mercury with increments of .1 in between to set them at 1.6? I've never looked at one.

If I am reading this right then you may be misunderstanding the specification.... When you synchronize the carbs you are adjusting them so that they all are pulling the same initial vacuum - the specification allows you up to a maximum of 1.6"Hg. (mercury) of variation between the minimum and maximum carburetors.  If you hook a manometer across the engine side of 2 carbs and the engine is running the manometer will show the difference in vacuum between the 2 carbs at that particular time - it doesn't matter how much or little vacuum you have it will show the difference between the 2 pressures.

Imagine a hose shaped like a "U" with the legs pointing into the air and it has some liquid in it between 2 pressure sources - on one side you have 5 pounds pressure on the other you have 7 pounds pressure.  If the pressure is constant the liquid in the hose will move toward the leg with 5 pounds of pressure in it until the height of  the column of liquid on the 5 pound side is sufficient to compensate for the difference in the 2 pressures.  Now if you measure the difference in height of the 2 columns of liquid in the legs of the "U" you can state this in a manner that can be replicated - such as  "the differential pressure was 10" of ATF" or if a heavier liquid such as mercury or glycol is used it will be a smaller amount of inches that will translate into taking the same amount of pressure to generate the differential.

Some fellows here have built slack tube type manometers and instead of using mercury for a fluid have used alternatives such as ATF which is a much "lighter" fluid and so the 1.6" Hg specification should be translated into an equivalent specification reflecting the lighter weight of the alternative fluid.  Others have used mechanical or electronic gauges of various manufacture.  It seems that most measure the vacuum at each of the 6 individual cylinder and then compare these readings to get to the final specification. 

The procedure for balancing the carbs uses #3 as the "master" as it cannot be adjusted  - think of the vacuum here as "0" (it's actual value may fluctuate but it is always the baseline)- now the others have to be adjusted so that they are referenced to #3 and as close as possible to that value (regardless of what it is) and the total difference from the highest vacuum of any of the 6 carbs to the lowest vacuum of any of the 6 carbs can be a maximum of 1.6" of mercury.

One of the shortfalls that I believe exists in most of the homebuilt systems is that they open end to atmosphere on one end and go to Vacuum on the other end - meaning that there is a large pressure differential, couple this with the use of lighter fluids such as ATF and the tube has to be even higher to accomodate the pressure differential from Atmospheric to cylinder vacuum.  These gages do accurately show the pressure at each cylinder and you can see the differential by comparing them all but they create their own difficulties by the manner in which they are constructed. 

If you construct you manometer so that #3 is onto a liquid filled manifold manifold then that side of the manifold is at whatever vacuum is being created by the restriction through #3 carb. and each of the 5 lines can be run to the other carbs and they will show the vacuum that those carbs are operating under.  Now you are back to recognizing the pressure differential between the carbs - the spec still needs to recognize the weight of the fluid that you are using and compare it to the weight of mercury in the original specification but the differential pressures that you are dealing with will be much closer in range.

[John U.]

"One of the shortfalls that I believe exists in most of the homebuilt systems is that they open end to atmosphere on one end and go to Vacuum on the other end - meaning that there is a large pressure differential, couple this with the use of lighter fluids such as ATF and the tube has to be even higher to accomodate the pressure differential from Atmospheric to cylinder vacuum.  These gages do accurately show the pressure at each cylinder and you can see the differential by comparing them all but they create their own difficulties by the manner in which they are constructed."
Posted by MadMike

The plans I've seen and the one I used to build mine aren't open to the atmosphere at all. In fact that is the only problem I've had using mine is to make it absolutely airtight. I added an elbow and a threaded adapter to accept a plug to the 3" manifold. The ideea was to make it easier to fill with ATF. The problem is that it leaks air, just a bit but enough that the ATF never stops rising in the individual tubes that connect to the vacume fittings, and eventually the manifold draws air when it runs dry. The ATF makes using caulk inefective and teflon tape doesn't seem to stop the leak. I guess I'll have to glue the plug in after I get it as full as possible. They do work well and are very sensitive if they are airtight.
In theory a manometer could be built so that the column of ATF is tall enough to balance the vacume with an open system but the tubes would be pretty tall, and the manifold large to hold a lot of ATF. Mercury is a heck of a lot heavier than ATF. Water or a water/antifreeze mix would be heavier but still not as heavy as mercury.

[HotRod]

Well I just ordered my six liquid filled gauges from Jags, thanks fordmano for the link,appreciate it!

[fordmano]

No problem HotRod, glad I could be of help.. That's also why I like it here lots of resources for us all to share.

[Ricky-D]

Yes, the height of a column of water or even lighter fluid like ATF  needs to be very high, like over 12 feet!

That's why those particular systems need to be air tight, in the reservoir system and connections. The risk is sucking the fluid into the motor.

In any of the systems, liquid or gauges, the problems are not insurmountable. Simply takes some thought and time, not to mention, money!

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