The Triumph Dolomite Club - Discussion Forum

Can the sprint carbs and or air filter go on an 1850?
Could i fit the sprint air box to 1850 su carbs and or replace the carbs with sprint and if so would it improve performance?

Just curiuos and more to do with future proofing with the increasing difficulty sourcing air filters for 1850's

Get yourself a set of TR7 carbs on manifold from the Triumph Show; they will bolt straight on. They have a Sprint style air box and use the same filter.

xvivalve wrote:Get yourself a set of TR7 carbs on manifold from the Triumph Show; they will bolt straight on. They have a Sprint style air box and use the same filter.

Hi Alun thanks which show please when, and where?

Triumph and MG show (it's more of a glorified autojumble) Stoneliegh showground Warwickshire, Feb 21st.

Steve

Ahh the Stoneleigh show. A little too far for me this year will have to see if i can source one elsewhere. There is a show and autojumble in June/ July in Bromley Kent - Bromley Pageant of motoring or something like that which is an annual event. Or I will keep an eye out on E-bay.

Maidstonerob wrote:Just curiuos and more to do with future proofing with the increasing difficulty sourcing air filters for 1850's

I wouldn't worry about air filters, the kit car world can supply alternatives.
These can either be to fit inside or externally attached to the air box.



The TR7 carbs and manifold will indeed fit the engine but, in 30 years of the DSR and TDC, I can only find one person who has tried this,
he being our very own Toledoman......who went back to 1850 carbs because the fuel consumption with TR7 HS6s was poor.

A Sprint or TR7 airbox has a bigger volume than that of an 1850, so it would really need to be modified to make its volume the same
before it would be suitable on an 1850. Such a modification may counter the excessive fuel consumption with HS6s......?




Ian.

I fitted a TR7 manifold and carbs to my 1850 many years ago primarily because the four-stud fixings of the carbs were much more stable than the wobbly two-stud fixing of the standard 1850 SU set up. However, if back then we had the solid alloy carb mounts for the 1850 that we now have, I don't think I'd have bothered swapping to the TR7 setup.

And I believe there will be little, if any, performance gain.
Smaller carbs should make for better mid-range power/torque. Too large may increase the very top-end slightly (but I doubt very much) but can make the low/mid ranges feel very woolly.

Add to that you are uncertain as to what needles would be needed.....

Thanks all for your views. Thankfully not an immediate concern as have 3 pairs at this point. Not sure about the K&N type bolt ons would prefer something more stock. Like the idea of modifyong the sprint airbox but dont understand why the volume would need to be decreased if its filtered and the mounts are the same would have thought the engine will just pull what it needs but to be fair I have never understood induction details of cars just so long ss it can take clean gulps of air as freely as possible is my limit of understanding!

It is difficult (for me) to understand the science but a simple test is to remove the air filter box and then try driving the car......
on SUs it'll lack power and responsiveness compared to before.
You can counter this by fitting long bell mouthed trumpets but then you have no filter...




Ian.

sprint95m wrote:It is difficult (for me) to understand the science but a simple test is to remove the air filter box and then try driving the car......
on SUs it'll lack power and responsiveness compared to before.
You can counter this by fitting long bell mouthed trumpets but then you have no filter...

Ian.

Solved.

Jeroen

soe8m wrote:

sprint95m wrote:It is difficult (for me) to understand the science but a simple test is to remove the air filter box and then try driving the car......
on SUs it'll lack power and responsiveness compared to before.
You can counter this by fitting long bell mouthed trumpets but then you have no filter...

Ian.

Oranje sokjes.jpg

Solved.

Jeroen

Brilliant! Wind socks!

Do other colours work or orange only?

Tony

Maybe you should pull these over the trumpets as a filter. You can use a sprint airbox instead of an 1850 one. The bigger the volume of the box the better it is. Trumpets do enlarge the airflow through the carb and so more efficiency/power.

Jeroen

Hs6 carbs on an 1850 are too big. The airflow is too low because of the bigger carb. You can solve that by using stiffer springs in the dashpot to have a smaller venturi again but that's the same as an hs4 again. No use.

Jeroen