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MG TD TF 1500 - Very fine tuning of SU carburetors

Has anyone tried modifing the SU needles as described in the Moss Motoring article https://mossmotoring.com/su-carb-very-fine-tuning/
For those who have done this what were the results and is the engine stock or modified?
Also was a wide band Air/ fuel ratio gauge used.
Safety FASTER!
Len 914 420 8699
Len Fanelli

It's pretty standard practice if you haven't got access to needle choices but really ,there's that wide a choice of needles available why butcher good needles-
The worst part is(and i stand guilty of doing it) is that you end up with needles that don't match the numbers stamped on them and that can end up being a real pain in the butt if you end up with a box of needles that aren't what's written on them.
I used to have, years ago a pushbike cable mounted into an old damper piston cap so i could see piston lift from inside the car on the road---A mechanical version of a vac gauge I guess, but it worked fine for needle tuning at part throttle settings
willy
William Revit

Willy with my Fast Road Roller camshaft 272-272 degree @ .016", not to be confused with my mislabled earlier Fast road> now Street performance roller camshaft. (I only produced 2 of these 272-272 camshafts but now will keep them in stock!)
Combind with my custom swirl polished 45 degree stainles steel valves, like the racers use. I used GJ,GS, AAE, #6, H1, LS1,Ao & RO needles, as well as elimanitang many others.
The RO was great above 3000 RPM, the AO was better under 3000 RPM but still had a stumble below 3000 RPM like the RO.
This is why I needed to modify the AO needle for a little better 1000-3000 RPM with the RO above 3000 RPM.
It took some time BUT the engine now has a a very flat torque curve from 2500-6000 RPM. Idles @ 600 RPM with great drivability from 1200-6000 RPM.
The drivability is now so good that it drives like it has stock camshatt in a 6 cylinder car.
Good enough to have been a MG factory option!
Len
Abingdon Performance Ltd.
Len Fanelli

Good stuff, it's the result that counts
Have you tried P4 needles, they work well with some combinations/camshafts

willy
William Revit

Thanks Willy the P 4 looks great!
I will have to try them:)!
Len
Len Fanelli

By the way Today I timed the difference between before and after finding the best air/ fuel ratio from Idle to wide open throttle!
With my TD, 4.3 axle ratio, 2nd gear from 2000 RPM to 4000 RPM, 5.0 seconds instead of 6.1 seconds.
I am certian this will work on ANY XPAG XPEG engine!
Well worth the time an money spent ( 2 sets of SU needles), Now I can reproduce any needle in an hour or two.All that is needed is the results of an A/F ratio from a wide band A/F kit :)!
Safety Faster
Len
Len Fanelli

By the way, the reason that the earlier GJ needles would not work anymore is because my 37 & 35 MM Stainless steel swirl polished valves with a 45 degree seat angle. They now flow so much more air that to unlock their potential power and torque the engine now needed the MGA 1622 needles.Almost a 25% bigger engine than my 1308 CC XPAG that is much closer to stock than race. > OEM crank, rods, pistons, cylinder head, 8.7:1 C/R & 216 216 @ .050" tappet rise or 270 advertised duration roller cam. The cylinder head will be ported this spring by Evanuik Performance. One of the best if not the best at making the T type heads produce more power and torque!Then it will go on a dyno!
Hope everyone has a GREAT MG New Year :)
Len


Len Fanelli

You will be happy with Jim's work. He's done great work for me in the past, but make sure to remind him about the Metric thread form.
Steve Simmons

Thanks Steve :)!
L
Len Fanelli

I know that Jim Evanuik does "Magic" with any cylinder head. Many of my customers and others that I recommended to use Jim Evanuik were very pleased. Even the best MG T racers found that his work improved the performance of their engines after using other performance cylinder head shops.
Jim and I have compared notes and I have learned from him and I have given him performance information on XPAG XPRG engines that he will pass onto MG T type customers, as they are not cylinder head related.
Safety Faster
Len
Len Fanelli

This thread was discussed between 05/11/2023 and 23/01/2024

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