I got mine from Burlen yes. Joe Curto can supply them also.
Mine are stamped on the shank, unfortunately it’s high up where the set screw can crush the mark. Otherwise a caliper measurement compared with a reference chart. Stock is M and that is what comes in kits.
I buy from Burlen. I get it shipped by Royal Mail, and usually it’s here in a week. I suspect all the needles you buy are ultimately Burlen in origin.
We found this as well in dyno testing. The UM is strictly for economy, one of a number of things Jaguar did to civilize the car at the expense of power - but hey - it was one of the most powerful cars sold at the time. Gas is different today - even the stuff without ethanol. I’ve had my E Type since 1972, back in the day UM’s worked well - no surging.
Hemi’s breath well, but are inefficient in combustion. It’s the result of a large combustion chamber, shaped like an orange peel.
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e mail: sales@su-rebuilders.com
web: su-rebuilders.com
SU Rebuilders Inc
325 West Washington Street, Ste. #2175
San Diego, CA 92103
Ray Opinion on swapping UE for UP???
BTW, the address is just a Mailboxes store. Probably some guy runs the company in his garage somewhere.
WOOP!! WOOP!!
Last guy I dealt with, like that, cost me a buncha expensive-to-replace chrome.
good to know…a lot of on line web sales are like that…but always the possibility…here today…gone tomorrow…as in Las Vegas…don’t put more money on the table than you can afford to lose…Nick
Hi,
Exactly! UM’s worked well from 1996 to about 2005/2006 after which I noticed while tuning that something was different, and then found out it was the fuel.
Cheers!
UO is my choice and the test is a long stretch of uphill motorway, where the car now pulls all the way to 5000 in 3rd. With UM it was struggling above 3000
I have to agree that the car feels great with UO. But it’s running very rich, so I have to think a somewhat leaner needle would still give fine performance, but better fuel economy and less carbon fouling. I’d like to be running around 13.8 at steady throttle, which would be just a few points rich using E10.
The thing I really want to look at is fuel enrichment under acceleration. There are many unasked questions there, such as spring rate, piston weight and oil viscosity, which can have a big impact. How much enrichment and what is the correct rate of change? The needles embody the arithmetic, but the calculus is in the piston.
Never tried UP. Agree that UO is almost always way rich at the top and would likely end up loading up your chambers with carbon.
I have the exact opposite experience, and to me this is a perfect example of why one really needs to experiment on their own and the internet recommendations of others should only be used to help one understand options, but not “the best” solution.
My car had UO when I bought it and seemed a bit rich with the previous owner’s K&N filters, and when I switched to a stock air cleaner solution it was way, way too rich. It would stumble and run very rough starting above about 3000 rpm, and by 4500 was not making any more power. I switched to the stock UM and immediately had smooth running throughout the range. It took a little tuning at idle to get the mixture right, but now it idles smoothly and pulls consistently throughout the range. It might be a tiny bit lean, so I might try some UB or UE just for fun to see how it runs.
I have a 3.8 and we can still buy real 98RON petrol (no ethanol). I have several sets of needles, it runs very nicely on UM’s, so I leave well alone.
But you’re south of the equator, so for you the UM is much richer and the UO are bone dry lean, right? 
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The vendor canceled my order for UX needles and returned the money. All’s well that ends whole, I guess.
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Here is a site that claims to have them, at a steep price:
https://www.sumidel.com/shop/category/-0125-fixed?search_custom_category=105574&page=3
I see that Moss sells UE needles, as they were standard in the Xk150S.
I’ve got an inquiry into a friend who works there to see where those particular needles are sourced from.
He already confirmed that Moss gets their needles from 3 or 4 sources.
BTW – The profile data on all SU needles is readily available. ANY machine shop could easily spit out a set in almost no time at all. Cost would likely be only slightly more than the prices I’m seeing for them from the usuals.