Correct Needles for my 120
Discussion
A quick look at the Burlen website shows the standard needle in the H8 as being VR. They even have a 25% off sale on at the moment.
http://sucarb.co.uk/carbspec/carburettor/essential...
http://sucarb.co.uk/carbspec/carburettor/essential...
Haynes list the VR needle too.
I can't find the H8 carbs in the official Jaguar XK120 manual.
I would have a chat with Burlen, I've always found them really helpful and they'll like know what is best. If you don't have the C-Type head on your XK120 then it might not want the same needles, but I wouldn't be able to say. Burlen put the sand cast carbs back into production a few years back so I imagine they've sold them to people with standard head arrangement and have some experience of best needles to choose.
I can't find the H8 carbs in the official Jaguar XK120 manual.
I would have a chat with Burlen, I've always found them really helpful and they'll like know what is best. If you don't have the C-Type head on your XK120 then it might not want the same needles, but I wouldn't be able to say. Burlen put the sand cast carbs back into production a few years back so I imagine they've sold them to people with standard head arrangement and have some experience of best needles to choose.
Right, you'll need to be careful here because if your car doesn't have a C type head it must have the original 120 standard head which had a different cam profile and smaller valves.
You have the added problem of larger carbs than standard, the fact that they are sand cast makes no difference to the appropriate needles.
What you have to do is use this chart :-http://www.mintylamb.co.uk/suneedle/
You can enter the present needle size and determine roughly what way you want to go; either rich or lean. You also have to consider the profile of the needle according to the state of tune of your engine. The last consideration is whether or not you are running pancakes or horns on the carbs as this drastically affects mid to high range power.
Once you get it nearly right it becomes easier to determine the dead right needle.
So that'll keep you busy for a few hours, eh?!
J
You have the added problem of larger carbs than standard, the fact that they are sand cast makes no difference to the appropriate needles.
What you have to do is use this chart :-http://www.mintylamb.co.uk/suneedle/
You can enter the present needle size and determine roughly what way you want to go; either rich or lean. You also have to consider the profile of the needle according to the state of tune of your engine. The last consideration is whether or not you are running pancakes or horns on the carbs as this drastically affects mid to high range power.
Once you get it nearly right it becomes easier to determine the dead right needle.
So that'll keep you busy for a few hours, eh?!
J
Meant to say I had a 150 DHC in a couple of weeks ago and used this chart to sort out the needles. Turned out it had a 3.8 engine with slightly unusual carbs from a 3.4 being a NZ import, and it was sporting pancakes.
The difference when finished and tuned was unbelievable; it was a bloody flying machine! So best of luck.
J
The difference when finished and tuned was unbelievable; it was a bloody flying machine! So best of luck.
J
When I fitted HD8s to the original engine on my XK150 one of the guys on the Jag-Lovers forum suggested a set of needles which he'd used on his with that combination. The 150 head is different to the 120 one. Actually if I remember right then weren't there different versions of the XK120 head, didn't they change the valve sizes part way through the life of the 120.
PM me the chassis numbers and I'll look it up for you if you like to confirm the sizes.
PM me the chassis numbers and I'll look it up for you if you like to confirm the sizes.
I can't find the details of the change in the valves now. The SE engine gets higher lift on the valves before the C-Type head becomes available with the bigger exhaust valve.
The other thought that comes to mind if it isn't running right on the new carbs is was the internals of the inlet manifold opened out to match the bigger throats of the 2" carbs? When I bought my HD8s from David Lonsdale he supplied them with a new inlet that was already machined out. I seem to remember that Guy Broad also offered a suitably modified manifold, but they were just machined out standard ones.
The other thought that comes to mind if it isn't running right on the new carbs is was the internals of the inlet manifold opened out to match the bigger throats of the 2" carbs? When I bought my HD8s from David Lonsdale he supplied them with a new inlet that was already machined out. I seem to remember that Guy Broad also offered a suitably modified manifold, but they were just machined out standard ones.
EXKAY120 said:
Now this is when i wish i had half a brain !! or at least be technically minded, Jith, can't you come down to Kent and sort it out for me, i'll make you a cuppa, and add some custard creams !!
I've got a much better idea. You come up here and I'll set your 120 up and then you can do a blast over the Rannoch Moor and take in the highlands all the way up to Skye. You won't believe the driving; it's the best anywhere.J
jith said:
......and then you can do a blast over the Rannoch Moor and take in the highlands all the way up to Skye. You won't believe the driving; it's the best anywhere.
Can you get to the Highlands from Rannoch Moor? Last year we ended up at Rannoch station after driving across the Moor and the road just stops! Agree about the roads though, blooming marvellous 
The Surveyor said:
jith said:
......and then you can do a blast over the Rannoch Moor and take in the highlands all the way up to Skye. You won't believe the driving; it's the best anywhere.
Can you get to the Highlands from Rannoch Moor? Last year we ended up at Rannoch station after driving across the Moor and the road just stops! Agree about the roads though, blooming marvellous Should be on every driver's bucket list.
J
EXKAY120 said:
Right, i've decided to do that….will it be the 3.8 E, top down, or the 120, ??????
But which of your 120s?They're both gorgeous, but I guess the views of the hills will be better in the OTS, but Jay Leno says it's his 120FHC that has women on Rodeo Drive draping themselves over it, would it have the same effect up in the Highlands?
With no disrespect to jith, who regularly gives excellent advice, I have always found personally that carburettor tuning is for the most part a disappearing black art. While a blast over Rannock Moor sounds enticing, there are a number of people far nearer you who can sort it, including CKL where my engines were built and tuned. I am sure there are plenty of others near you who are members of this black circle too.
EXKAY120 said:
Now this is when i wish i had half a brain !! or at least be technically minded...
When I was young I found this interesting to do myself. Admittedly it was on MGAs and MGA Twin Cams so only 2 SUs not 3 but it was a great way to learn, swapping needles, going for a run and eventually getting it right. Playing with it is how you learn. lowdrag said:
With no disrespect to jith, who regularly gives excellent advice, I have always found personally that carburettor tuning is for the most part a disappearing black art. While a blast over Rannock Moor sounds enticing, there are a number of people far nearer you who can sort it, including CKL where my engines were built and tuned. I am sure there are plenty of others near you who are members of this black circle too.
Aye well lowdrag, to be a carburettor wizard you have to be a past grand master in the Lodge, a member of the Knights Templar and be secretly known to the Illuminati. All joking aside, I've been tuning them for over 40 years so I think I can manage the odd XK or E. But they're a piece of cake compared to the 12 chokes on a Ferrari Boxer.
By the way a8, we don't have hills up here, they are mountains, and we have hundreds of them. And for the benefit of doubt exkay, the blokes in kilts tend to drape themselves over the women! Exkay, is your 120 the Saluki Bronze one that you posted up a while ago? I love that colour.
J
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