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MG TD TF 1500 - SU H2 alternative richer needles

In a earlier post Jim Barry mentioned that a GS needle works better than a GJ in a H4 carburetor, as it is richer offf idle I am now very happy with the resuts of the GS, Thank you Jim. ( The LS1 & H1 were horrible, for me )
Now wondering what would be an alternative needle for H 2 carburetors, off idle, and not neccesarily the EM needles.
Safety Fster!
Len
Len Fanelli

You can use this site and select any needles you like to see a comparison of what they might give you up and down the scale. http://www.mintylamb.co.uk/suneedle/
L E D LaVerne

I installed an AEM air/fuel gauge in the far side of the glove compartment and spend a lot of time looking at it. I don't see any other way to really know what is going on with the mixture. The GS needle (used for MGA) has the smoothest curve I could find in our range.

Jim
J Barry

Thanks La Verne and Jim.
I have used the Mintylamb site for my H4 application on my car and have an AEM A/F meter installed.
Therefore I am asking if anyone has done this with H2 carburetors,when a richer off idle needle is needed, such as when one of my Abingdon Performance Ltd. Roller lifter cam kits have been installed :).
Len
Len Fanelli

If you are running a light damper oil and want things richer off the line then I would suggest that you replace the oil with some GL-4 90 wgt gear oil. That is what Moss sent out with their MGB super charger kit to accomplish that feat. Stronger piston springs over stock will also help a bit.
L E D LaVerne

Hi Len,
This might be useful or not. Either way, it adds a complication which I have not read anything about.

When I first fitted my supercharger (mid 1970s) I had to "feed" the throttle on gently as I accelerated, otherwise the engine "gasped" and lost power. At the time I had no idea it was related to damping.
I raced the car like this for quite a while until one day I found some NOS carb piston dampers and fitted one. Pushing it down into the carby I noticed that it felt weaker in damping effect than the one I took out! I then went to my "Carby parts" box and found a few other old dampers. Experimenting with the old ones I picked another old, well-used one which was stiffest to push down into the carby and fitted that. Next time I went racing I could apply full throttle without the "gasping" effect.
This raises the issue that it is not only the oil which affects damping, but the damper itself. Do they come in different strengths?? Maybe it is just a quality control thing?
I know that my experience was not just off-idle, but damping could still be the issue as L.E.D. suggested.
Bob Schapel

They are related directly to each other. Stiffer valve or thicker oil does the same thing.
Steve Simmons

Stiffer valve or stiffer spring?
Regards, Tom
tm peterson

Len are you asking compared to the std ES needle or compared to the EM
I find that the EM gets rid of the dull feeling down low but is too rich up in the revs
"IF" that's what you find as well try a FO needle
William Revit

EM vs FO! Yes Willy FO looks great on the Mintylamb site!
Again this is not for me. This is for anyone with H2 carburetors who are looking for a richer needle than standard, but not the originally recommended ones, as they all seen too rich! The same as in my case when the LS1 & H1 were much too rich and the GS needles worked about as perfect as can be, compared to the standard GJ needles.
Thanks Willy!
Len Fanelli

Yeah, GS needles are great in 1 1/2" carbs--1275 Cooper S's had GS needles and i've been running them them in XPAG's with 1 1/2's for years, they're just right for the fuel with low dose ethanol--not so sure what they'd be like in an XPEG though, might be a tiddle rich 'maybe' on the larger engines but then might be fine.
Cheers
willy
William Revit

Len not to confuse those with H2 carbs.

Referring now to H4s
In talking with Manley Ford yesterday I was able to get the complete car spec document that he wrote along with Craig Chima’s notes. Manley recommends RO needles over the GS. Looking at the http://www.mintylamb.co.uk/suneedle/ while comparing the GJ/GS/RO graphs it appears the the RO are slightly richer over the GS but follow a similar graph line rise. Have you tried ROs. May be too much for a muffled fast road car. I will try out the GS needles on a fast road trek, do plug readings and decide my next step. Possibly trying the ROs for further testing. This is while using the 236/236 Andrews, Further ignition timing tweaks may be necessary

Bill Chasser
TD-4834
W A Chasser

Thanks Bill, but my Abingdon Performance Ltd MG T type roller cams have not been produced by Andrews for many years. I have since moved on to Crane Cams which became Comp Cams as they are more willing to produce them in a more timely manner. Now 3 weeks from ordering to at my door step!
By the way CompCams no longer produces ANY MG camshafts, except for my exclusive T type roller cams.
Len
Len Fanelli

Just to confiirm, I have a TDII with the correct 1.5in carburettors. These have GS needles plus unspecified springs and dashpots with light oil. Is this a reasonable set-up, particularly are springs 'normal'?
Ian Bowers

Yes Ian, unless the engine has been modified.
Len
Len Fanelli

Thanks for the feedback, Len.

I think it is now 1500cc or near, a skimmed head and cut back valve surrounds (done by Alastair Naylor in the 1980's) taking compression to around 10.

Does that change the answer fundamentally?
Ian Bowers

Yes Ian I am about to try RO needles as Bill Chasser stated above!
len
Len Fanelli

This thread was discussed between 09/06/2023 and 25/07/2023

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