Stromberg jet height

[SESH]

Hi Rob,
Just read my invoice and it says, late CD Manual Jet Conversion rather than Needles! They removed the fixed jet seats and installed a manual jet adj conversion kit. The parts were £55.00 per carb + VAT.
It was done by ATSPEED at Rayleigh, Essex, where they also Dyno tune.
Mike

[Doug Buchan]

Im trying to get my 1973 UK spec car to run better.

I'm rebuilding the Strombergs. Is there a definitive figure for how far below the bridge to set the jets?

Hi,
Over here it's recommended to set the jet .125 below the bridge. That's what I did on my old S1 XJ12 and it worked.... ok. If I ever have a car with Stroms again, I would opt for the adjustable jet set up

Here's a link for the proper tools if you need to press the fixed jet.

https://www.skandix.de/en/installationp ... 4/2000520/

[Doddsy]

Doug, NigelD, many thanks for reposting the link to the proper tools for setting the jet height. I had missed this previously. I have just placed an order for 1037412 and 1037414 which looks to be what I will need to do this even with carbs in situ. (I had planned to take the carbs off today so just in time!). 75 Eu including shipping. I will report back on how I get on.

[Doddsy]

An update on my progress with the Strombergs on my car. The proper tools for adjusting the jet height arrived very promptly from Skandix in Germany. There is the press itself and also a “depth setting gauge” which has two ends for two different depth settings

These were very straight forward to use although I did practice on a spare carburettor that I happen to have before letting loose on my car. Everything was done in situ and took just a matter of minutes. That is unless like me you wanted to measure the new depth of the jet (so removal of the air valve etc).

All you need do is remove the aircleaners and damper. The depth setting gauge is installed first. It is place around the needle and sits into the jet orifice. This gauge is mounted on the end of a short rod allowing it to be properly located through the air intake (see photo). You just need to lift the air valve so it slides around the thinner part of the needle.

The press has a short insert which locates in the top of the damper tube (which is part of the air valve). The press screws straight into the top of the carb cap and presses the air valve down via the insert and damper tube which transfer the pressure to the gauge and then the jet itself.

I used a short tube extension over the press handle as it did take quite a lot of pressure to move the jet. This moves all at once which is a little unnerving the first time. The depth setting gauge profile is such that the jet is accurately positioned. I did check all my four carbs using a digital vernier calliper which are now all set at 0.100” below the bridge as measured to the land (not the centre to the jet).

The only problem which I encountered was that the depth setting gauge has two depths neither of which is 0.100”. It was very straightforward to use a feeler gauge to limit the depth of the setter. The photo shows this in action.

I have now adjusted the needle valves using a colortune plug. At the 0.100” depth this is in the middle of the adjustment. I rebalanced the carbs and have just been for a spirited drive. Im very pleased with the results.

[Adamski]

By jet height I am assuming needle height which has the same effect for Stromberg.
My experience has been to get them approximately right and perform by using four Colourtunes. (one for each set of 3 cylinders)
I then performed road trials and did plug reads to weaken/richen accordingly.
Seem to remember that rear two carburetors deviated slightly from front two at finale,