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Synching the carbs - old school
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T
Tinster
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Guest
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You must be joking?!!
I tried the old hose in the ear trick and could detect
no difference in sound, no matter what angle I held the
hose at. I used the sync tool with tube at 45* and it worked just fine.
Maybe 'cause I'm so old I be goin' deef?
d
I tried the old hose in the ear trick and could detect
no difference in sound, no matter what angle I held the
hose at. I used the sync tool with tube at 45* and it worked just fine.
Maybe 'cause I'm so old I be goin' deef?
d
Moseso
Jedi Knight
Offline
In all these carb sync threads no one mentions the old-school SU tool kit that has the two posts, with "cat whisker" wires, that you insert into the pistons in place of the dampers. You move the two wires until they are right next to each other and pointing right at each other and then start the car - realigning the two wires by adjusting the idle screws. They work just fine at wider throttle openings too.
I got a set of those with my first TR, and a lesson in how to use them. I've tried the hose and the Uni-Syn and they work, but no better or faster than the SU tools.
Truth be told, I've never understood why SUs have this "hard to work on - hard to synchronize" reputation. I've rebuilt 'em several times. It's hard to imagine anything easier...
I got a set of those with my first TR, and a lesson in how to use them. I've tried the hose and the Uni-Syn and they work, but no better or faster than the SU tools.
Truth be told, I've never understood why SUs have this "hard to work on - hard to synchronize" reputation. I've rebuilt 'em several times. It's hard to imagine anything easier...
Tim Tucker
Jedi Trainee
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The 'old school' title caught my eye. I found this on another site and found it interesting. I have yet to try it since my cars are running well (knocking on wood). I would love to hear comments on what you think or feedback if you should try it. Tim.
"One day I was tuning an MG with the scope and an exhaust analyzer when I noticed an old man watching me. In this shop customers were allowed in the shop area and he was waiting for his car to have some service work done on it. He asked about the equipment and I didn't mind so I explained a little about the analyzer and the scope and how we could adjust mixture on the carbs with the analyzer and even see a difference in scope patterns when rich or lean. He said he was a mechanic when he was young and that he had to adjust mixture without any equipment on cars in the 30s and 40s. He explained how he did it by adjusting the throttle idle speed down as low as he possible make it still idle. Then he would turn the mixture screw which ever made the engine either smooth out or speed up. Then he would turn the throttle stop screw down again to get the engine to run as slow as possible, and repeat the mixture adjustment to get it to speed up. He soon arrived at a point where if he turned the mixture screw in either direction the engine would die. He would then reset the idle stop up to normal idle speed and it was finished. He was going on the idea that his ideal mixture for idle would make the most horse power at idle. (slightly richer than stoichiometric)
I was working on an MG with two SUs so I tried it instead of the standard method using the piston lift pin. I used his method and when finished I checked it with the CO equipment and it was well within range. I got curious so I got a fuel injected car and used his method on it and when finished I checked it and it was also well within proper range. Within the next few weeks I checked several different kinds of cars and it worked on everything I tried it on. And I thought I knew it all. Here was a man who had not worked on cars since the 40s. Who showed me a method to just about match what high tech equipment could do even on an electronic fuel injection systems which had not even been invented when he had quit working on cars. He was using the internal drag of the engine itself as the drag of a dynamometer. He forced the engine to labor to just keep running and turning the mixture screw which ever way made it speed up. The reason it speeded up was because it was producing more power. He would force it back slow again to put it under labor again and he would arrive quickly at a point that if he made it leaner or richer it would loose power and die. This was for idle mixture adjustment only as that was all he had an adjustment for. I wonder how many other low tech solutions there are to high tech equipment."
Here is the entire article:
Crab PDF
"One day I was tuning an MG with the scope and an exhaust analyzer when I noticed an old man watching me. In this shop customers were allowed in the shop area and he was waiting for his car to have some service work done on it. He asked about the equipment and I didn't mind so I explained a little about the analyzer and the scope and how we could adjust mixture on the carbs with the analyzer and even see a difference in scope patterns when rich or lean. He said he was a mechanic when he was young and that he had to adjust mixture without any equipment on cars in the 30s and 40s. He explained how he did it by adjusting the throttle idle speed down as low as he possible make it still idle. Then he would turn the mixture screw which ever made the engine either smooth out or speed up. Then he would turn the throttle stop screw down again to get the engine to run as slow as possible, and repeat the mixture adjustment to get it to speed up. He soon arrived at a point where if he turned the mixture screw in either direction the engine would die. He would then reset the idle stop up to normal idle speed and it was finished. He was going on the idea that his ideal mixture for idle would make the most horse power at idle. (slightly richer than stoichiometric)
I was working on an MG with two SUs so I tried it instead of the standard method using the piston lift pin. I used his method and when finished I checked it with the CO equipment and it was well within range. I got curious so I got a fuel injected car and used his method on it and when finished I checked it and it was also well within proper range. Within the next few weeks I checked several different kinds of cars and it worked on everything I tried it on. And I thought I knew it all. Here was a man who had not worked on cars since the 40s. Who showed me a method to just about match what high tech equipment could do even on an electronic fuel injection systems which had not even been invented when he had quit working on cars. He was using the internal drag of the engine itself as the drag of a dynamometer. He forced the engine to labor to just keep running and turning the mixture screw which ever way made it speed up. The reason it speeded up was because it was producing more power. He would force it back slow again to put it under labor again and he would arrive quickly at a point that if he made it leaner or richer it would loose power and die. This was for idle mixture adjustment only as that was all he had an adjustment for. I wonder how many other low tech solutions there are to high tech equipment."
Here is the entire article:
Crab PDF
poolboy
Yoda
Offline
I like it. He probably set the timing the same way by using his senses. Sight, sound and feel. Until the automobile's electronic age, what else did we have?
I remember back in the 70's many a mechanic would say the shadetree mechanic's days are numbered. That's what I like about vintage cars. You can use a little common sense, go back to basics, and just about overcome any obstacle.
Of course the modern age has made it possible for us to put our heads together on Forums like this.
I remember back in the 70's many a mechanic would say the shadetree mechanic's days are numbered. That's what I like about vintage cars. You can use a little common sense, go back to basics, and just about overcome any obstacle.
Of course the modern age has made it possible for us to put our heads together on Forums like this.
Offline
Being then and now one of those "shadtree mechanics," I used to feel that way. But I don't any more. On modern cars, the diagnostic procedure sometimes might be a bit more difficult, especially if one doesn't have access to OBD II scanners and the like, but I've found I'm still perfectly capable of performing most of the same jobs on newer cars that I've long tackled on Triumphs and the like...sometimes, to this day, literally under the shade of a tree!poolboy said:
But even with diagnosing problems, I've found that, as often as not, my "gut" feelings still tend to work, although it took my son to spot the wobbly needle and broken spring on the speedometer of his Toyota Paseo, and it took both of us several R&Rs before we found the right way to both swap another speedometer into the otherwise good instrument cluster (the rest of the "new" cluster didn't quite match his year Paseo) and the properly install and connect the cluster. Those sorts of tasks are much more time-consuming on newer cars, to be sure. (Guess what, TR6 owners? There's really not any more room to work under/behind the dash of a '92 Paseo than there is under/behind the TR6 dash!)
Oh, I'm sorry to say I've never tried the hose trick. I've got the SU kit and have used it, but mostly I still rely on the Uni-Syn I bought over 25 years ago and which still retains its original box and instructions.
BTW, I won't bore you all with details, but suffice it to say that the "official" procedure of adjustment of a Solex carburetor on a Herald is not much different than that of the "old man" in Tim's post above!
GBRandy
Jedi Knight
Offline
I had a stethoscope an old Brit Car mechanic gave me when I had my MGB. It was a solid aluminum tube plugged into the hearing tube that split and went into the head piece.
I have long since lost it, but it worked great. Hopefully i can make one once I find a TR3 to buy
I have long since lost it, but it worked great. Hopefully i can make one once I find a TR3 to buy
2wrench
Luke Skywalker
Offline
tdskip said:
What does one (meaning a mechanic) look like in this process? I have heard
so much about it. Likely, me and Dale would have a hose bouncing around
the engine bay trying to hear something. (Sorry to drag you in, Dale)
Works for a TR6, I suppose? Come on you old timers, the challenge is
on: Show us in a short video series this lost art. I think it would
be waaaayyyy super cool to learn. Man, could I look like I know what I'm
doing or what?
I think I'd invest in a stethoscope, bastardize it, if need be. It's
about hearing the difference in the air rush, right?
Come on, show us, please...pretty please....
Offline
I confess I never really knew how the "hose trick" worked. Does one listen for volume or pitch? (I'm hoping it's the latter, since I happen to have perfect pitch, but I also have some loss of hearing in one ear, so volume might be harder for me to judge. :wink: )
poolboy
Yoda
Offline
I use a sthethoscope, a cheap one. The part that the doctor holds against your chest is the amplifyer. It plugs onto the hollow tube. Remove it. You then have a tube with about a 1/4 inch hole.
That part of the stethoscope is small enough to accurately place in the same relative place in the mouth of each carb. Because the difference in the sound can be very subtle when the carbs are close to being insync, it is very important to place the tube in the same relative place in each carb.
For the 175 CD ZS carb, there is a convenient reference point.
One of the screws that hold the float chamber on has a threaded hole thru drilled to the mouth entrance, about a 1/4 inch from the air box flange. Use that as a reference point or place the tube right there.
The tube is rigid enough that you can let it extend several inches from your hand, thus not obstructing the in rushing air.
You listen for the volumn and tone of the hiss of air. Do it and it will be obvious the type of noise you will expect to hear.
Similar to the hose in the ear, but 2 sources for error are eliminated with the sthethoscope. One, exact placement in the ear and two, exact placement on each carb. Both are necessary for consistantcy in your evaluation.
Check places like Walmart for a cheap stethoscope
Oh yeah, when I had a stuck valve, you could hear it the same way. Instead of a steady hisss, you could hear more of a swish,swish, swish.
Another good use for the scope is to replace the amplifyer, wrap a soft layer or 2 of cloth around it, hold it to things like your alternator, valve cover, water pump, distributor, etc to listen for normal and abnormal sounds.
I don't think you'll need a video. Use your imagination for uses. You'll think of dozens of ways.
That part of the stethoscope is small enough to accurately place in the same relative place in the mouth of each carb. Because the difference in the sound can be very subtle when the carbs are close to being insync, it is very important to place the tube in the same relative place in each carb.
For the 175 CD ZS carb, there is a convenient reference point.
One of the screws that hold the float chamber on has a threaded hole thru drilled to the mouth entrance, about a 1/4 inch from the air box flange. Use that as a reference point or place the tube right there.
The tube is rigid enough that you can let it extend several inches from your hand, thus not obstructing the in rushing air.
You listen for the volumn and tone of the hiss of air. Do it and it will be obvious the type of noise you will expect to hear.
Similar to the hose in the ear, but 2 sources for error are eliminated with the sthethoscope. One, exact placement in the ear and two, exact placement on each carb. Both are necessary for consistantcy in your evaluation.
Check places like Walmart for a cheap stethoscope
Oh yeah, when I had a stuck valve, you could hear it the same way. Instead of a steady hisss, you could hear more of a swish,swish, swish.
Another good use for the scope is to replace the amplifyer, wrap a soft layer or 2 of cloth around it, hold it to things like your alternator, valve cover, water pump, distributor, etc to listen for normal and abnormal sounds.
I don't think you'll need a video. Use your imagination for uses. You'll think of dozens of ways.
TR3driver
Great Pumpkin - R.I.P
Offline
Yup. But Herman has lots of them, so no big dealpoolboy said:
Actually, what I feel would be just as effective, would be if you could duplicate the "SU Tool Kit" to fit the ZS carbs. It has hollow rods that fit into the dashpot shafts, and then bent wire pointers that fit into the top of the rods. You bend the pointers so they match with the engine off, and then get a direct visual indication of whether they match, not just at idle but when you open the throttle.
Made it easy to get the TR3 carbs in sync, not just at idle but with the throttle open a bit (which means the linkage has to be slightly twisted at idle).
poolboy
Yoda
Offline
That's what's so good about the sthethoscope. You have both ears working and you don't have to be so concerned if you have the tube the same distance from your ear canal as you move from one carb to the other.
***** Sorry, Randall, I was typing this in response to your previous post about your left ear.*****
I have tinnetus, which is a constant ringing of the ears. Just like when a gun goes off and your ears ring afterwards except it NEVER stops.
***** Sorry, Randall, I was typing this in response to your previous post about your left ear.*****
I have tinnetus, which is a constant ringing of the ears. Just like when a gun goes off and your ears ring afterwards except it NEVER stops.
TR3driver
Great Pumpkin - R.I.P
Offline
Man, I HATE it when that happens! Fortunately, mine faded away after I got the message and quit spending so much time in the computer room. Back then no one worried about how much noise a (mini) computer made, and ours made lots.poolboy said:
Sorry to hear yours is more persistant.