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 Posted: Jul 19, 2018 04:48PM
jeg
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Blue Potato - 

//browsemags.com/mini-magazine-may-1-2013/982-su-carburettor-tuning.html 

Don't know if you've read this article, but it's got some really GREAT information in it. 

For example, check out the paragraph on dampers - 

The peasants are revolting...          

"Gone with the Wind" - a brief yet moving vignette concerning lactose intolerance

 Posted: Jul 19, 2018 04:26AM
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US
I have mailed over a set of AH2 s since we live so close together. It only took three hours round trip last visit. I'm also confused as I have talked with AC Dodd about needles many times. And watched the videos of a hand drill chucked in a vise to spin needles. I did not know KD was hands on since his son in law took over the biz. Steve (CTR)

I like books and had a good collection of both SU and Weber info. Have a SU needle chart book at home and the shop. as well as the big SU book. I do comparisons on old scraps of paper. My O2 gauge has been the biggest help. O2 , EGT and vacuum are all helpful. With twins a Unisyn is a must. 

 Posted: Jul 18, 2018 06:00AM
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US
Quote:
Originally Posted by h_lankford
Quote:
Originally Posted by thebluepotato
There is no way to tell based on this what specific needle you have - you need to start with one (lets say M needle for now) and get on a rolling dyno in order to see what your A/F is at different stages on the RPM range. 
That " no way" may not always be true. I started with my 1275 "Stage 1" and going by butt dyno through BFY, BDL, too lean- BDK too rich ( soot all over back bumper) that this website's recommendation for "lightly modified use" BCE worked well. Then went to dyno and found it was good based on A/F ratio, BCE was what I needed. Slightly rich on low rpm end but that gave good driveability.

Howard's 2 carb set up and more advanced cam and state of tune may make for a different carb-tinkering experience.
At the end of the day, you cannot get an accurate reading of the optimal burn and HP/TQ for your modified mini engine.  Case and point - take a look at my before and after dyno run from two weeks ago.  This is a good example as to why it is critical to do it on a dyno to get the right idea of where you are. 

Before (red line): This was my first run with my mini where I assumed the car was set up correctly.  Ran great and had a needle that was recommended with no dyno runs or understanding where the A/F was.  This is not the right way to do it and was dangerously lean and lower power.

After (green line): after cross referencing needles and trying some and using others to make up the optimal A/F gap, we found the right one during the session - but you can clearly see that I am still running rich at tip in.  My pal and I are no cross referencing the 300+ needles to find one that can slightly lean out the mixture (i.e. going slightly ticker at top of needle) and keep the optimal A/F after 3k.  And will also be trying out a new dashpot damper (AUC8114) and possibly a different SU spring - again, looking at another dyno run to get that green line smoothed out.

So I do not side with the "read a book at pick your perfect needle" concept - unless you combine that with a couple hours on a rolling road to truly understand where the optimal power is.  This is the only way to know what needle to use.  Otherwise, you are guessing like I did on that red line you see above.

/// Basil - 1974 Mini 1000 /// THE BLOG: www.thebluepotato.net/blog

 Posted: Jul 18, 2018 03:57AM
 Edited:  Jul 19, 2018 04:57AM
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Quote:
Originally Posted by Scargo
Does anyone out there with more knowledge than me care to take a stab at making a recommendation for a needle selection for my street driven Sprite? Engine spec is: 1293cc Kent 276 cam 1.5 roller rockers 12G 1316 Smog head slightly ported Compression ratio approx 10:1 Header with single box exhaust Pertronix Dual HS2's w/ K&N single box air filter
Howard, Keith? Dodd was very good with helping Joe Schott on a needle selection when he built his 1293 engine. The end result was he took the needle suggested by KD and "fine tuned it" in a drill with some 2000 grit sand paper to get it where he needed it.
The air fuel ratio was spot on when he was done.

If in doubt, flat out . Colin Mc Rae MBE 1968-2007.

 Posted: Jul 17, 2018 01:30PM
 Edited:  Jul 18, 2018 03:01AM
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Quote:
Originally Posted by thebluepotato
There is no way to tell based on this what specific needle you have - you need to start with one (lets say M needle for now) and get on a rolling dyno in order to see what your A/F is at different stages on the RPM range. 
That " no way" may not always be true. I started with my 1275 "Stage 1" and going by butt dyno through BFY, BDL, too lean- BDK too rich ( soot all over back bumper) that this website's recommendation for "lightly modified use" BCE worked well. Then went to dyno and found it was good based on A/F ratio, BCE was what I needed. Slightly rich on low rpm end but that gave good driveability.

Howard's 2 carb set up and more advanced cam and state of tune may make for a different carb-tinkering experience.

 Posted: Jul 17, 2018 06:17AM
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US
Quote:
Originally Posted by Scargo
Does anyone out there with more knowledge than me care to take a stab at making a recommendation for a needle selection for my street driven Sprite? Engine spec is: 1293cc Kent 276 cam 1.5 roller rockers 12G 1316 Smog head slightly ported Compression ratio approx 10:1 Header with single box exhaust Pertronix Dual HS2's w/ K&N single box air filter
There is no way to tell based on this what specific needle you have - you need to start with one (lets say M needle for now) and get on a rolling dyno in order to see what your A/F is at different stages on the RPM range.  This is done through a lambda or something similar.  It is only then where you will start to hone in on the right needle for the perfect mixture.

Just spent 5 hours myself a couple weeks ago and was astonishing what you can learn and dial in for the perfect needle.

/// Basil - 1974 Mini 1000 /// THE BLOG: www.thebluepotato.net/blog

 Posted: Jul 17, 2018 01:26AM
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I will have a go .... m needles 

 Posted: Jul 16, 2018 10:09AM
 Edited:  Jul 16, 2018 04:40PM
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Does anyone out there with more knowledge than me care to take a stab at making a recommendation for a needle selection for my street driven Sprite? Engine spec is:

1293cc

Kent 276 cam

1.5 roller rockers

12G 1316 Smog head slightly ported

Compression ratio approx 10:1

Header with single box exhaust

Pertronix

Dual HS2's w/ K&N single box air filter

 Posted: Jul 14, 2018 03:49PM
jeg
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Quote:
Originally Posted by tmsmith
Graham:
There is a replacement tool from the MK-1 forum.
It does require you to install Open Office as there is some programming that is not compatible with MS Office.

from a forum post:
In the meantime, if you have "LibreOffice" or "OpenOffice" on your computer,
you may be interested in this needle comparison tool:
(IT'S NOT DESIGNED TO WORK WITH M$ OFFICE)
//mk1-performance-conversions.co.uk/technical_carb.htm

Terry
The Mk1 'Needles' tool is far superior to both the MintyLamb and Teglerizer needle selectors in that rather than simply compare needle dimensions - which you can do yourself using a needle chart book and Excel sheet - the Mk1 'Needles' comparison tool compares the annular area between the needle and jet of your selected needles. 

There's also a function which allows you to lower or raise the jet and 'see' the effect change in annular area as a percentage, as with the usual compare a handful of needles, similarity recommendations and the ability to modify a 'test needle' for comparison (fx. removing 0.002" from position 5 of an AAA results in (x)% change from the standard dimension.

Using this tool, you can also compare 0.100" needles to 0.090" needles - as sometimes, with HIF carbs, one fits a larger jet to a smaller carb or vice versa. 

Ian presented this comparison tool to Berlen Fuel Systems last year or so and they were highly impressed.  I haven't spoken with Ian since the last revision, so I don't know if Berlen will be incorporating his work to their website.  Yes, I'm biased - I assisted Ian with some development opinions and quality checks, making the odd data correction and giving feedback prior to release.

The peasants are revolting...          

"Gone with the Wind" - a brief yet moving vignette concerning lactose intolerance

 Posted: Jul 11, 2018 06:50AM
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this might help

scroll down to taper selector section

//teglerizer.com/sucarbs/index.html

 Posted: Jul 11, 2018 06:42AM
 Edited:  Jul 11, 2018 06:45AM
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Howard
 - I just tried it and got nowhere also

does this one help any?


www.winsu.co.uk

this hyperlink does not work, so copy and paste

 Posted: Jul 11, 2018 06:03AM
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Does anyone have an update on this? I need to make a needle selection and I'm struggling with the Burlen site.

 Posted: Nov 10, 2017 02:42PM
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US
Story posted on that web site, now. Sounds like it will be resurrected.

 Posted: Nov 10, 2017 12:53PM
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Graham:
There is a replacement tool from the MK-1 forum.
It does require you to install Open Office as there is some programming that is not compatible with MS Office.

from a forum post:
In the meantime, if you have "LibreOffice" or "OpenOffice" on your computer,
you may be interested in this needle comparison tool:
(IT'S NOT DESIGNED TO WORK WITH M$ OFFICE)
//mk1-performance-conversions.co.uk/technical_carb.htm

Terry

 Posted: Nov 10, 2017 11:17AM
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US
Anyone know what happened to the "Minty Lamb" website for SU carb needle comparison graphs?
It was a great way to compare the hundreds of needle option when doing modified engines.
If anyone know how to reach the person who created it please let me know.

Graham 949-646-6404