As per the original post MG, I'll have a crack at a linear device if you're prepared to pick up the cost of the sensors once done. I think I'll have it operate onto an analogue voltmeter from 0 to full scale. Analogue gives not only the final value, but also is easy to watch for progression....(why some gauges like manifold pressure are left this way even today).Use it in cahoots with your lambda sensor like you originally said and I reckon you'll get a lot of use out of it in an enjoyable way. It is a hobby afterall, not the UN.

Let the naysayers snap out a few more emails from their typewriters and I'll get onto it this week....after I've gone to the beach, and the museum...and smashed out a mean vindaloo...and had my fill of daytime telly...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Sounds like you have a very busy life, Mick.
You also cook curries?!

Far be it that myself or Matt or GR or Morris try and help you understand that there is more to tuning a SU than knowing where the damper is sitting, it won't hurt anyone but I just want people that this gizmo is only one part of a very complex answer and that the rest of the equipemnet to actually be able to make sense of tthe readings is both expensive and time consuming to fit

O2 sensors are quite comon but they are designed to be fitted to the exhaust manifold to work best, tail pipe readers are Ok but a bit slow and you need the exhaust to be perfect with no leaaks at all but you must know all this as you dismiss what has been said by myself and others in this thread, I have read the first post annd am simply trying to help you out but you don't need help so please disregard evrything that Myself and the others have tried to inpart to you, i hope you have great luck building your widget

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

Thankyou.... but would you use one if it worked well?

probably not it is like a colourtune I dont need ome of them to set idle mixture when SU fitted a lft pin that works jsut as well

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Roundies and Clubbies(except vans) are both ugly that is why I have Midas and a van
1293 Mini Midas Bronze,1275 Clubman van

if you have 4 seperate carbys and 4 exhausts then it is easy. The tune-up guys at RB racing have all the gismos like air flow meters, fuel flow meters, exhaust pyros etc,etc and a the soft ware package to do all the tuning you want and to calculate the HP / torque out put for the specified load on the engine. With the air flow meters and each cylinder vaccume measurement will give a accurate reading allowing for the variable air restricter position
The problem with twin carbys on 4 cylinders and siamese exhaust is that you will not know what cylinder is lean and what one is rich. A exhaust gas annalilizer fitted to the common out -let can give a good reading , but 2 cylinders could be lean and 2 rich.
I use a simple set-up on SU's to measure the piston position . it consists of a piece of alloy tube fitted into the hollow piston rod that is marked with graduations of 1/8" to correspont to the needle. the top of the piston chamber has another piece of alloy tube clamped to it to give you the base graduation.
For air flow I use a pair of monometer tubes. just made from perspex tube ,a piston inside and a fitting to bolt to front of carby.

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

Well folks, we've done it! And whats more it not only works but provided (and logs) useful info like CO, SU piston height, Manifold Vacuum and RPM. And yes, you can easily tune the SU from the info and some needle spread sheets.

If some could tell me how, I can post a log here.

Mick, how are you going with yours?

Well done GT! ....I knew it could be done.... Just took a little bit of
independent thinking..somebody with a little extra smarts... eh?
It didn't take you long.
So what method did you use to measure piston position?
I think we should name it the "GT Mowog PC Tuner"

Actually, I've been working on this in my head for a number of years now - on and off, however the final way to do it came to me in about a minute - when I started looking out side the square - always the way. I wanted to do it in a way that would not change the way that the SU operated and could easily be fitted without modification to the carbie.

It presently fits 1 1/4"and 1 1/2" and I haven't checked yet but should also work with 1 3/4" Carbies. Still working on a how to fit to HIF SUs and have come up with a rough idea, hope to try it out over the weekend or early next week.

It will measure the piston movement to with 10 thou and has (so far)100% repeatability

You could photocopy or scan it and then post it as an image.

i would assume a log would be in a txt format file? if so just paste it in quote brackets [] that should be sufficient. if its a print out, yeah scan as an image and upload like normal

Sorry, I hope this works....I've not yet posted pics at all here.

EDIT> try again.....

and again....

[img][img]http://img163.imageshack.us/img163/2294/session2a20091126.jpg[/img]
By gtmowog [/img]

GT, I'm just trying to work out what the lines mean?

It hasn't posted very clear here regretably.

The upper 'jaggered line' is the Air / Fuel Ratio.

The lower 'laggered line' is the SU pistion lift. I've calibrated it in inches but can be easily converted in to mm.

I have put in some vertical lines to show results at that particular point. Say look at the vertical line on the right, it shows;-

Black Number is the time elapsed in to the log (1 min, 38 sec)
Pink Number is the A / F Ratio (22.39 : 1 - bit lean eh?)
Red Number is the SU Piston Lift (0.56")

Also notice the generally correlation between the A/F Ratio and the Pistion Lift?

It does show that the needle does need to be thinner at the thin end. It can be quite finitely analised and I have a spread sheet that I can work with that (from where this one is) will get you very close for needle selection - maybe spot on - but more likely one further selection. I'd say after doing a few, I'll better have the hang of it all and would be able to select the corect needle (or custom profile) in a single go.

GT..Since you keep the carby intact...would the Mowog tuner help in selecting spring weights?
Also..would the tuner help in quickly deciding if the carby has air leaks (worn throttle shaft ect)