STE carburetor synchrometer

deQuincey

deQuincey

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hello

a friend has lent me a ste-synchro, type BK

i would like to make some meassurements, what value should i expect at iddle ? ( the scale is in Kg/h )

the device came with an opening in the bottom that can be opened or closed by rotating the conical rubber adapter body, what should i do during meassurements ?

who is the owner of this marvelous installation ? what is your experience and tips on the operation ?
montajeparasincronizaciondecarbs-1.jpg
 
It's an air balancing device for carbs. Set the openings the same ( about 5/8" to 3/4" or metric equivalent- based on the weber site where they sell the adapters), then adjust your carbs to equal.

They work on the same principal as the factory procedure.

I would also switch the meters from one carb to the other, just to make sure they read the same.

Steve has the same devices, maybe he wrote down his findings at idle and 3000 rpm. Equal is what you're shooting for though.
 
Are two Synchrometers really needed or can you use one and just move it from one carb to another as you adjust each?
 
One will do. Buy the cap or make one up like in the picture. The secondaries are slightly cracked open to prevent sticking.
 
i have a brand new one of these synchrometers (never used - in box) if anybody is in the market for one. i bought it for my last 2002 - but sold the car before i ever used it ... and didn't need it on my e30 m3.
 
That's my setup in the picture...I had 2 meters until a backfire blew one of them up. It's not necessary to have 2 of them, just convenient. Like Jerry says - swap them to give you peace of mind that they are giving the same reading and equal is all you're looking for. Having 2 frees you up to make adustments without havng to keep swapping them from carb to carb. There is no set value for the meters - it's all relative, you just want them to be the same at idle and through the rev range. Adjust the mixture and throttle butterflies for the appropriate rpm, the meters will show how much air each carb is getting and of course you want the carbs to be equal. Twisting the base will let you have a sensitive setting for idle and then turning it will allow you to make them less sensitive for higher rpm's. Here's my latest set up, a cool old meter set from the early 70's I got from Germany with the Zenith fittings, it also came with about 10 other vintage carb tops.

IMG-20110731-00464.jpg
 
wow, wow, steve, i am envious about your cool, i will say more,...sexy setup with that beautiful oldtime meter !!!:mrgreen:

my answers in blue:


Stevehose said:
That's my setup in the picture...I had 2 meters until a backfire blew one of them up. It's not necessary to have 2 of them, just convenient.
i only have one, so i will swap it from one to the other

Like Jerry says - swap them to give you peace of mind that they are giving the same reading and equal is all you're looking for. Having 2 frees you up to make adustments without havng to keep swapping them from carb to carb. There is no set value for the meters - it's all relative, you just want them to be the same at idle and through the rev range.
ok

Adjust the mixture and throttle butterflies for the appropriate rpm, the meters will show how much air each carb is getting and of course you want the carbs to be equal.

Twisting the base (twist to open the lateral hole ? or to close it? ) will let you have a sensitive setting for idle and then turning it (again open or close the lateral hole?) will allow you to make them less sensitive for higher rpm's.
why making them less sensitive in high rpms ?

Here's my latest set up, a cool old meter set from the early 70's I got from Germany with the Zenith fittings, it also came with about 10 other vintage carb tops.
:mrgreen::mrgreen::mrgreen::mrgreen::mrgreen:
Click to expand...
 
hole closed = idle, hole open = higher revs, it allows more air in so the meters don't max out the scale. With one meter you'll have to find a way to hold it at a steady rpm and then switch from carb to carb. The beauty of 2 allows you to watch the acceleration/transition from idle to high revs and dial in the linkages so they breathe the same through the rev range. I don't remember but there are 2 models - the BK and I think the SK - one is more sensitive than the other and therefore less suitable at high revs.
 
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I used to have one of those and did the swaping from one carb to the other. Not very convenient.

To answer your original question: on my car, which has the exact same engine and carbs as yours, my 1000rpm idle would read 9-10kg/h per carb.

That´s after tuning the mixture with this very helpfull fellow:

http://www.gunson.co.uk/item.aspx?cat=673&item=1822

But I don´t use SK Syncrometer anymore, I´ve found to get better sync with a twosome of these

http://www.scheuerlein-werkzeuge.de...ontestuhren/synchrontester-boehm-2-uhren.html

Important to use the 0.6-Version as the 0.4 will be overloaded by the big vacuum that the M30 creates in the zentih manifold (1.5 Liters of displacement sucking...).
having those two, connected directly to the manifold (I use the connector on the brake booster side of the manifold as I´ve blocked the connection to the air filter anyway) I get a very precise reading and can play with the revs, sync not only idle but also load conditions and can watch the sync when revving up, thus optimizing the burl knob adjustment in the linkage.

@dequincey: As my carbs are currently nicely synched and have no reason to go off synch; I´d be happy to borrow you may pair of gauges. Provide me with an adress (you´ve got my email) and I´ll post them to you.
 
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hi, thanks

Tierfreund said:
I used to have one of those and did the swaping from one carb to the other. Not very convenient.
well, it is not mine, i only wanted to check it as i have some doubts with the vacuum meters

To answer your original question: on my car, which has the exact same engine and carbs as yours, my 1000rpm idle would read 9-10kg/h per carb.
mine, reads 12kg/h per carb (this is the mark between 10 and 14)

That´s after tuning the mixture with this very helpfull fellow:

http://www.gunson.co.uk/item.aspx?cat=673&item=1822
interesting, we should discuss this method with a beer next october:-D

But I don´t use SK Syncrometer anymore, I´ve found to get better sync with a twosome of these

http://www.scheuerlein-werkzeuge.de...ontestuhren/synchrontester-boehm-2-uhren.html

Important to use the 0.6-Version as the 0.4 will be overloaded by the big vacuum that the M30 creates in the zentih manifold (1.5 Liters of displacement sucking...).
this is my system, i bought two vacuum meters (0 to -1bar)
vacuometros.jpg

the question is that i am plugging them here:
montajeenganchedetubosdetalle.jpg

and i don´t like the meassurement, the needle is constantly shaking while reading

you are right that the sync is very straightforward with this method, and also the high rev and the burl knob adjust

having those two, connected directly to the manifold (I use the connector on the brake booster side of the manifold as I´ve blocked the connection to the air filter anyway) I get a very precise reading and can play with the revs, sync not only idle but also load conditions and can watch the sync when revving up, thus optimizing the burl knob adjustment in the linkage.
do i understand you well?, are you connecting to the same point as me ? ( i have blocked the air filter connection also ) if that is the case,...do you have the mentioned vibration in the needle of the gauge ? or do you have a steady condition ?

@dequincey: As my carbs are currently nicely synched and have no reason to go off synch; I´d be happy to borrow you may pair of gauges. Provide me with an adress (you´ve got my email) and I´ll post them to you.
thank you so much for this kind offer, i assume that my gauges are similar to yours, (this is a 0 to -1bar reading scale)
Click to expand...

regards
 
As usual, you´re going all the way... :)

First off, yes, I use the same vacuum take off point as you. I believe it to be ideal as it is full manifold vacuum under all conditions. Also, if you, like me are no longer using these points for anything else, you´re not changing the setup in any way from the actual running conditions and can even leave the full air cleaner attached while tuning (not for convenience, but for precision)

The reason your needles are jumping so much ist that they are regular vacuum dials. The engine doesn´t create a constant vacuum though. It´s a pulsing vacuum that pulses with the strokes of the engine. You´re basically looking at three air pumps as found on a bicycle that are connected through the manifold, thus you get a pulse in the vacuum whose frequency varies with the revs.

The boehm synchro clocks have a separate damping device built into then (adjustable through a knob on the vac line that allows one to adjust the damping so you just get a steady reading with still a very quick response to changes in the vacuum. Unfortunately I do not know how exactly that mechanism works and how you could build such a mechanism yourself.

But maybe you can figure it out from the descriptions on their website:

http://www.boehm-synchrontester.de/manual_grossbritannien.html

Looking forward to that beer...
 
Looking at the description of the Boehm dials on their website, it seems that the variable damping mechanism seems to be no more that a rubber washer with a very small inner diameter that is squashed by a ring nut to modify the inner diameter. So you may be able to get some reasonable damping by simply experimenting with a piece of smaller diameter tube feeding your dials. If you have a rubber line, you may even want to try squashing it by hand to see if a reduced throughput makes the needle jump less. Don´t worry about the accuracy of the reading: as long as the vacuum get´s through at all, the dial will read correctly, it´ll just even out the pulsing.
 
Tierfreund said:
... the variable damping mechanism seems to be no more that a rubber washer with a very small inner diameter that is squashed by a ring nut to modify the inner diameter. So you may be able to get some reasonable damping by simply experimenting with a piece of smaller diameter tube feeding your dials. If you have a rubber line, you may even want to try squashing it by hand to see if a reduced throughput makes the needle jump less. Don´t worry about the accuracy of the reading: as long as the vacuum get´s through at all, the dial will read correctly, it´ll just even out the pulsing.
Click to expand...

hey, that is great !

i love your explanations in which the phisical reasons are underneath the facts, it is really interesting to know what to do taking into account which are the principles that rule the action

i will check it as soon as possible
 
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