ahoy there mateys, i lashed out the other day and ordered myself a gunsons colourtune from the uk, it came today (less than a week delivery, very impressive!!) anyhow, i whacked it in and had a sneeky peek at what my Supercharged (with 92's kit) engine was actually doing, besides what seems to be a little miss in spark, (a distributor thing??) i was suprised that according to the instructions i had actually set the fuelling pretty right for idle, score 1 trent. Then i gave it a bit of a rev and my sense of acheivement went shooting out the exhaust along with the burnt gas. The lovely blue shade i had changed into a mix of blues and yellows but mainly yellows, meaning that fueling isnt actually right So according to the colortune instructions my fueling is allover the place at revs. Im gunna assume that its a needle thing (havent actually changed it from standard) and possibly a cam issue, anyone else got any insight as to what it could be?
Actually i might even film it when i can be bothered and stick a link up to it on here for you all to see.
goodnight and have a pleasent tomorrow
trent

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That all sounds quite reasonable to me. . .
Colourtune is really only any good for setting the mixture at idle. You can get some sort of idea as to how the motor is running at higher revs but it's not entirely accurate. If you give the throttle a blip and watch the flame colour, you would expect it to change to yellow - that's the accelerator pump 'effect' of the oil in the SU dashpot doing it's job - you want a relatively rich (yellow) mixture upon acceleration.
Of course, sitting there revving the engine in the driveway wont give you accurate mixtures anyway - there is no load on the engine. . .which is why people with plenty of money to chuck around always suggest getting a dyno tune done.
While it is true that a dyno tune with accurate exhaust gas anaysis will give you the best results quickly, I still believe you can achieve very good results by driving the car and listening carefully and feeling how it responds to changes in carb/needle settings (bring on the vitriol ) .
Dynos are great - but people did manage to tune cars before they were widely available! Patience and plug cuts still work suprisingly well (although unleaded fuel makes it a bit more difficult) and you learn a whole lot more about your car!

I got ripped off heavily on dynowork. But it gave me a good starting point and told me the issues (and some more that the tuner made himself) to fix at home. And exhaust sensor and an A/F ratio guage helped very much too! I must say the A/F guage is not perfect, but it's good and I would not say it's necessary as feel and car performance give it away easily too.

Colourtune is great! - For idle mixtures (don't burn that hand! hehehehe) But it's up to you for the rest. I've got my mixture pretty well spot on underload, when revving it's a bit rich but goes good (optimum range) when under load. That's the other thing, the car's gonna be quite different underload than just revving, hence the use of a dyno, anyone can shove a sensor in the back end and rev it up.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

check this link out, it suggests how to tune a car without a dyno but usint the colortune. Good luck and I hope your car doesn't fall off the stands...

http://www.niksula.cs.hut.fi/~mdobruck/siililand/mini/diy/10/dyno.htm

cheers

chris

yeah a standard needle will definitely not cut it on a boosted motor,
you can set it up to idle nicely but how it runs in the rev range is directly tied to the profile of the needle..

And jet mate. They go together. A fast raod needle and a hi-flow jet seem to be good but I can't say too much on needles mines a custom one.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

What is a high flow jet?
By that I mean, how does it differ from a standard jet?

It's bigger.

Has a bigger hold that your needle goes into. I'm not actually 100% sure what it's called, the AU book shows the HIF jet to be the part in the fuel bowl. But it connects to seat which is wider.

Basically thats what my tuner was saying and what I've heard many people call it.

It allows more fuel past your needle.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

Strange. . .
So it effectively makes your needle richer across the board.
1&3/4 inch and 44mm carbs use 100 thou jets. . .and the needle is altered to suit the tune of the engine.
Would have thought that just sticking in a bigger diameter jet would be a bit of a blunt tool as far as carb tuning goes. . .but, hey, if it works, it works. . .

thanks for the info everyone, now my next question, best place to get a new needle from, Ive been told a bdd or dbb needle from a metro turbo engine could be a good start.

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Personally, I'd probably try SUmidel ( www.sumidel.com ).
Generally pretty good with stuff and they may be able to give you a suggestion (based on your engine specs) as far as a good needle to try (although this might be difficult with the supercharger).

Yes it does but I guess if you jsut go ahead and put a bigger diamter in it would make things silly, I probably shouldn't have suggested it one it's own, I had a tuner ding for me, on the original jet with the richest non-sutom needle it was not good enough, with the bigger jet it was too much, so a combined needle and jet combo sorted it for me. Actual dyno figures in the current state are unknown, for now.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T

did you go back and get it re-tuned? or was this suggested to you and you did it at home?

The High flow seat slinkey is talking about is the needle and seat that allows fuel into the float bowl the standard one is not big enough and the float bowl runs out of fuel, that is the problem you were having not the mixture needle and seat. The standard mixture seat is fine and the needle is just sized to allow the correct amount of fuel to get the required air fuel ratio.

Kasper I posted awhile ago some needles that may be OK, I measured a dyno proven needle and looked up on some needle tables and found a couple that were similar from memory they were CS1 or CS2

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4efte powered Clubman
supercharged 998 race car

Thanks 92, I the wrong impression, John kept saying seat then jet then seat again, It confused me, he knew what he was talking about luckily.

No I didn't go back otherwise I'd know the hp. There really is no reason to go back, he knew from before what it needed and jsut put it in and I put the carby back on the car, the A/F ratio reads upper optimum while under load so it's pretty on and it goes faster now than it did before and doesnt throw black smoke out the back.

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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T