Home made TBS manometer question.

[John Dickens]

Hi,

I've decided to pension off the Morgan Carbtune in favour of a 'U' tube manometer.

If I use Automatic transmission fluid do I have to have some sort of damping restrictors in the connecting tubes to stop the fluid levels fluttering or is it viscous enough to get by without?

 

John

[Boffin]

Hi,

I've decided to pension off the Morgan Carbtune in favour of a 'U' tube manometer.

If I use Automatic transmission fluid do I have to have some sort of damping restrictors in the connecting tubes to stop the fluid levels fluttering or is it viscous enough to get by without?

 

John

 

ATF is quite low viscosity, I found I had to use restrictors. I used plastic connectors from an aquarium supply shop at the top of the mounting board. Below (ATF side) these I placed the end off of a cotton bud. I also found I needed to glue to connectors to the ATF holding tube to prevent them working loose.

 

Cya, Andy

[Rob L]

Increasing the tube diameter that holds the fluid will also lessen the flutuation in the levels.

[westco]

My home made ATF manometer sucked the ATF into the engine on startup. It had restrictors. By the way the restrictors are available at NAPA. They are listed under vacuum line connecters. I went back to using mercury carb sticks.

[Boffin]

My home made ATF manometer sucked the ATF into the engine on startup. It had restrictors. By the way the restrictors are available at NAPA. They are listed under vacuum line connecters. I went back to using mercury carb sticks.

 

There is always the risk of this if one side or the other is nor properly sealed, or if the balance is way out to start, that is why it is important to use a liquid the engine can ingest without harm. Thanks for the tip about NAPA but this is no use to John as we don't have NAPA over here. The cotton-bud restrictors work fine, though I have considered adding resevoirs above the fluid which will in themselves provide damping and catch any pull-through of fluid.

 

Cya, Andy

[oldvic]

A perfect restrictor when using ATF is the white inner core of co-axial television cable. Cut a short length (2 mm) of co-axial cable, strip it down to the hard white inner core and pull out the copper conductor from the white inner core. The result is a restrictor that works well with ATF.

[ruok]

Hi,

I've decided to pension off the Morgan Carbtune in favour of a 'U' tube manometer.

If I use Automatic transmission fluid do I have to have some sort of damping restrictors in the connecting tubes to stop the fluid levels fluttering or is it viscous enough to get by without?

 

John

 

John,

 

As others have said, ATF is pretty thin (low viscosity). I've used 5w-20 with good results. You could even try something thicker like 10w-30 or 20w-50. Another poster said he even used gear oil (80w-90) with good results.

 

FWIW, I believe I used 3/16" ID, 5/16" OD clear hose I purchased at Home Depot (I'm not totally sure, so please verify). The hose fit the brass vacuum outlets on my R1150RT perfectly without adapters (nice, snug fit).

 

Also you might try increasing the length of hose above the oil in your manometer. I'd make sure you had a least a foot or two of hose rising above the oil in your manometer in the event your sync is way off. Should give you some room to work until you get your sync a little closer.

 

Ken

[FlyingJoe]

I used 80-90w gear oil and found no need for restrictors. Also the amount of liquid in the U tube will make a difference (more mass, less acceleration). With 16" of vinyl tubing height above the oil, oil will not get sucked into the engine unless one side is not sealed or the engine is so completely out of whack it should barely run. I zip'tied the vinyl tubing round the nipple's just for safety sake and to insure no leak.

[powerman]

i used ATF, like the red color, you also can use more tube with more oil for more damping. can coil up the extra tube with oil

[Pilgrim]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

[Boffin]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

 

It is easier to see the levels with ATF, my manometer is mounted on my garage wall a few feet away from my bike lift and with the ATF I don't need to swap my glasses. I did think of water plus food clourant but was concerned it might start to decompose and stink up the garage.

 

Andy

[Big_Gray]

Hello John:

I am using a home made manometer with ATF in 1/4" tubing. I keep about three feet of fluid in each leg (when balanced)and the bottom of the U is at floor level. the top of the tubes are about 5 feet off the floor before they loop back down to the throttle bodies. No restrictors!

 

So far I have never come close to sucking any fluid over the top and I find the red color very easy to see. I can usually balance to about 3/4" differential at 4000 rpm.

 

I think that should equate to about 1 mm of Hg. or a little less. I sure don't think I could do that with Carb Stix.

 

I don't need no stinkin restrictors

[powerman]

dito on what big gray said, and the reason i use ATF is that i have a half a dozen quarts that i can't use in any of my vehicles and has been there for 10 years so i have plenty.

i have also mounted mine on the bike with the tubes comeing up the dash around my rcu shelf and back down, cenetred my levels between speedo and tac, ran that way for a month, dialed it in at speed. just don't focus on it to long when driving. use a heat resistant tubing. when it got hot it sucked closed due to the high vacum

[Pilgrim]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

 

It is easier to see the levels with ATF, my manometer is mounted on my garage wall a few feet away from my bike lift and with the ATF I don't need to swap my glasses. I did think of water plus food clourant but was concerned it might start to decompose and stink up the garage.

 

Andy

 

Ohhhh . . . I shudder to think what you might be using for food coloring, that it would decompose and start to stink. Do you actually put it in food?

Pilgrim

[Boffin]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

 

It is easier to see the levels with ATF, my manometer is mounted on my garage wall a few feet away from my bike lift and with the ATF I don't need to swap my glasses. I did think of water plus food clourant but was concerned it might start to decompose and stink up the garage.

 

Andy

 

Ohhhh . . . I shudder to think what you might be using for food coloring, that it would decompose and start to stink. Do you actually put it in food?

Pilgrim

 

Well, cooking isn't my forté, so I don't risk messin' with things I don't understand

 

Andy

[jkersh1]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

 

If some of the fluid does get sucked into a cylinder, a petro-based fluid like ATF has some chance of being combusted. Water isn't going to burn, and has a chance of hydro-locking the engine.

[Pilgrim]

Why, in the name of Holy Simplicity, use ATF or anything else in place of water? There are zero real advantages to anything else, and water has advantages not found with oils.

 

Pilgrim

 

If some of the fluid does get sucked into a cylinder, a petro-based fluid like ATF has some chance of being combusted. Water isn't going to burn, and has a chance of hydro-locking the engine.

 

 

Not even a little bit of a chance, unless you're using something the size of a garden hose. Calculate the volume required vs what's in the recommended tubing; you'll see.

 

Water will flash to steam, trust me on that, I've seen it, with no ill effects. The engine will stumble and maybe die, but nothing bad will happen, like big clouds of blue smoke and fouled plugs. You might even get the benefit of blowing some of the carbon out, which used to be done on purpose by spraying a little water into the carb throat.

 

Pilgrim

[RFW]

Hi,

I've decided to pension off the Morgan Carbtune in favour of a 'U' tube manometer.

If I use Automatic transmission fluid do I have to have some sort of damping restrictors in the connecting tubes to stop the fluid levels fluttering or is it viscous enough to get by without?

 

Viscosity it totally irrelivant. What matters is MASS. The more mass the fluid has, the less the liquid column will repsond to rapid pressure changes. ATF or any oil is the worst choice in this respect, because it has the lowest specific gravity of any commonly available fluid.

 

The easiest form of damping is to cut the head off a screw that is a tight fit in the plastic tubing, and shove the threaded shank into the tube. The air now must wind its way helically along the restriction of the roots of the threads, which will offer very substantial resistance to airflow.

 

I take it that you intend to use the manometer to measure the DIFFERENCE between the 2 cylinders? If you intend to use 2 manometers (one for each cylinder) then you will need 30 foot tall manometers!

 

Bob.

[FlyingJoe]

Viscosity it totally irrelivant.

 

Not true, the viscosity will determine how quickly the fluid can deform. For example silly putty is considered a liquid with a very high viscosity ( poise value ). If it was in a U tube it would 'jiggle' quite a bit less than say water and get pulled through the tube and a much slower rate for any given applied pressure. (and getting the putty in the tube would be a feat too)

[ShovelStrokeEd]

Just hook the thing up in differential mode and run plain old H2O. Add a little dye if you need the contrast. Get the two columns within an inch or so = < 1/4" Hg and just go with it.

[Spat]

Here is another vote for water, easy to use easy to clean up. I carry mine in the tail section in case I need a siphon hose.

I also like the decarbonization aspect, not enough water is used to cause any hydro lock up.

[RFW]

Viscosity it totally irrelivant.

 

Not true, the viscosity will determine how quickly the fluid can deform. For example silly putty is considered a liquid with a very high viscosity ( poise value ). If it was in a U tube it would 'jiggle' quite a bit less than say water and get pulled through the tube and a much slower rate for any given applied pressure. (and getting the putty in the tube would be a feat too)

This only makes sense if the tube is VERY small in diameter, or has a built-in restriction. For any reasonable diameter (say 6mm or 1/4"), that is simply bent into a U, viscosity plays essentially no part whatsoever. The liquid is just moving along the tube as a "slug" of fluid with little to effectively resist it.

 

Bob.

[FlyingJoe]

This only makes sense if the tube is VERY small in diameter, or has a built-in restriction. For any reasonable diameter (say 6mm or 1/4"), that is simply bent into a U, viscosity plays essentially no part whatsoever. The liquid is just moving along the tube as a "slug" of fluid with little to effectively resist it.

 

I suppose this is just splitting hairs as either liquid will work, a more viscous liquid will require less dampening however. The force required is strongly corrolated to diameter (forth order) but also directly related to viscosity, (first order) Poiseuille's Law

 

On a more practical empirical level, one can show this by taking a tube and pouring different viscous liquids, ie water vs honey into it and watching migration times.

 

Bottom line Bob things viscosity plays less/no role, I think more but almost any liquid will work

[RFW]

Technical points aside, in today's politically correct world, the word "manometer" is a no-no! Henceforth, please refer to this device as a "Personometer"! Can't have this blatant sexism, ya know!

 

Bob.

[BucksTherapy]

I know you weren't looking for a story but I just gotta share it.

 

Built Manometer, used water and red food coloring, set it all up and made proper connections for differential mode. Started bike, started fan, allowed bike to warm up while glancing at manometer and tinkering in garage.

 

As bike warms up all of a sudden it loads down and significant amount of white smoke out the exhaust. Bike now idling terribly and I don't have enough sense to turn it off. Start to smell smoke. Time to shut it down. No fluid in manometer.

 

Moral of the story. If you are using plastic hose don't route it under your catalytic converter. It melted through, sucked the manometer dry, burn't the melted hose to a crisp and ran rough from the inbalance.

 

Observation: 1/2 cup of water with red food coloring will not hurt an 1150RT when sucked into intake but will give you quite a thrill.

[powerman]

I found my picture of how i ran it for a about a month, i had the tupperware off. was able to dial it in over most speeds. never got it silky smooth like others report though.

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