SU Needles

[cliftyhanger]

It also had a 4.11 diff

But the reality is the slant 4 is a better engine. Certainly pulls better, and more economical. Not a lot heavier either. Downside is the water pump and stupid head stud angle.

Of course, our mk3 spit has approx 110 or so BHP from a 1300. That thing is quick, and actually very economical at "ahem" motorway speeds. Twin 40's, fast road cam, headwork etc etc. Pulls well too, and that is partly down to the megajolt map doing things a clockwork dizzy can't (reduces advance in one area where the cam normally has a torque dip) . Then there is my yellow spit, 180bhp+ from an engine that cost me £1700 by the time it was in the car, rebuilt and running with all engine ancillaries. That IS good value. Oh, and it will do 40mpg
People ask why I don't do std cars. Answers above. Saying that, I could be tempted by a dolly 1850 when the Toledo expires. Think I need to keep the sprint box and axle though, the 1850 is probably a bit delicate for me. See,there I go again....

[xvivalve]

From Terry Hurrell's Triumphtune performance manual:





Back in the day, these modifications were justified by both RR and track experience.

If you look at the actual profile dimensions of different needles, any old feller who 'opened them up' with a bit of emery cloth did so in a most unscientific and inaccurate manner and it is perhaps best that such folk have retired!

[cliftyhanger]

Alun, sadly those needles are all for twin carb setups. I still have my TT manual, and had a look. But they didn't seem interested in single carb engines then (or indeed now!)

Re altering needles, Gerald Dale was a revelation. in 15 minutes (once he had got all the base settings corrected) he had a dead even 4% CO over the entire rev range. He made it look easy, but things like that are a dying art. I know many expect a rolling road to hold 100s of needles, but the reality is few ever have. Profile altering works, but yu need to know what you are doing, and a way of measuring the emission. Guess an AFR gauge would do.

[xvivalve]

Alun, sadly those needles are all for twin carb setups. I still have my TT manual, and had a look. But they didn't seem interested in single carb engines then (or indeed now!)

Re altering needles, Gerald Dale was a revelation. in 15 minutes (once he had got all the base settings corrected) he had a dead even 4% CO over the entire rev range. He made it look easy, but things like that are a dying art. I know many expect a rolling road to hold 100s of needles, but the reality is few ever have. Profile altering works, but yu need to know what you are doing, and a way of measuring the emission. Guess an AFR gauge would do.

That's why I included the paragraph beneath the chart with their opinion of single carb set ups; it looks as if the needle choice was less relevant in their opinion than the manifold.

[soe8m]

Alun, sadly those needles are all for twin carb setups. I still have my TT manual, and had a look. But they didn't seem interested in single carb engines then (or indeed now!)

Re altering needles, Gerald Dale was a revelation. in 15 minutes (once he had got all the base settings corrected) he had a dead even 4% CO over the entire rev range. He made it look easy, but things like that are a dying art. I know many expect a rolling road to hold 100s of needles, but the reality is few ever have. Profile altering works, but yu need to know what you are doing, and a way of measuring the emission. Guess an AFR gauge would do.

Lambda readings are the ones to check while driving to see the mixture is ok. Old blokes using that dying art just putting enough (too much) fuel in causing fast ring wearing and then oil burning dying engines. In the land of blind one eye is king.

Jeroen

[GlenM]

Alun, sadly those needles are all for twin carb setups. I still have my TT manual, and had a look. But they didn't seem interested in single carb engines then (or indeed now!)

Re altering needles, Gerald Dale was a revelation. in 15 minutes (once he had got all the base settings corrected) he had a dead even 4% CO over the entire rev range. He made it look easy, but things like that are a dying art. I know many expect a rolling road to hold 100s of needles, but the reality is few ever have. Profile altering works, but yu need to know what you are doing, and a way of measuring the emission. Guess an AFR gauge would do.

That's why I included the paragraph beneath the chart with their opinion of single carb set ups; it looks as if the needle choice was less relevant in their opinion than the manifold.

Those paragraphs relate to single/twin Weber set-ups not the SUs. There are two types of manifold listed for a single Weber.

[xvivalve]

Those paragraphs relate to single/twin Weber set-ups not the SUs. There are two types of manifold listed for a single Weber.

Good point!

[cleverusername]

Alun, sadly those needles are all for twin carb setups. I still have my TT manual, and had a look. But they didn't seem interested in single carb engines then (or indeed now!)

Re altering needles, Gerald Dale was a revelation. in 15 minutes (once he had got all the base settings corrected) he had a dead even 4% CO over the entire rev range. He made it look easy, but things like that are a dying art. I know many expect a rolling road to hold 100s of needles, but the reality is few ever have. Profile altering works, but yu need to know what you are doing, and a way of measuring the emission. Guess an AFR gauge would do.

That's why I included the paragraph beneath the chart with their opinion of single carb set ups; it looks as if the needle choice was less relevant in their opinion than the manifold.

Those paragraphs relate to single/twin Weber set-ups not the SUs. There are two types of manifold listed for a single Weber.

Which is odd, because the more I look into it, the more I have come to think twin carbs are a bit pointless. Very little extra gain, harder to setup and a larger single carb offers the same benefits.

Burt Munro, who held the 1000cc world speed record thought the same. With a modern injection setup, each cylinder has its own injector, allowing optimum fuelling. In theory a multi-carb setup should have a similar advantage, in practice it doesn't seem to work that way. I assume, because the carb isn't bolted directly to the cylinder and is less effective at atomising fuel compared to a modern fuel injector.