Su jet height

[Iansparky]

I have a question about the height of the jets o my carbs, if I set the jets to the recommended 60 thou below the bridge the car won't run, I have ended up with the jets around 110 thou down and I still think it might be too lean, the plugs are white around the insulator and the exhaust pipes are only very slightly black when I wipe my finger on them. The needles are set so a 2 thou feeler gauge slips in the grove and the float bowls are set to 7/16. The car is a pig when it's cold ( need to laeve chock lever at run till it warms up) but seems to run beautifully when warm. I am just a bit worried that if it's too lean I might damage the pistons. Ignition is all brand new and timing set to 10 degrees dynamic.
What does everyone think

[mgcjag]

What level is the fuel in the jets.....double check your needles the code should be printed/stamped on them

[Iansparky]

Will check needles and fuel level then report back, there are um needles, I already checked that

[mgcjag]

Is UM on the needles or was it on the packet?

[caveman]

Did you follow Andrew Turveys tuning setup:
https://www.dropbox.com/s/6pmcaqykapw7n ... e.pdf?dl=1
I’ve followed this a number of times but set the initial levels each at 65thou or by the set up instructions in the workshop manual and averaging the three out. This should get you running. I found that initially I had white(ish) plugs so gave each carb 1/4 turn to richen them up slightly. The carbs stopped popping and idles smoother with static timing also at 10°.
Prior to initial start, I made sure the choke cable was disconnected and a good gap was observed on the fast idle screws before firing up and final settings (as per manual/guide above).
Originally and for some time before this,I was running rich with very black plugs, this led to a diagnosis of excess play in the throttle butterfly shaft guides letting too much air in. My front carb idle screw was fully in as it struggled to balance correctly. I’ve since had Burlen reset my bearing/guides and a huge difference.
There is advice on this site (search Mixture) that suggests initial setting of 65thou & 5% CO which again is pretty close and worked for me initially. I think I’m at approx 70-75 thou but now the car is smooth I don’t intend to let OCD force me to get the verniers out again!
I do have UM needles but one of them was not quite level in the Dashpot so ensure this is checked first. I also put a new set of plugs and leads on to ensure ignition wasn’t the root cause. Inexpensive too.
I’m still awaiting a good few runs in the car to re check plug colours and tweak but all good presently. Remember the Dashpot oil levels. What’s your fuel pressure like? (2-3psi).

[abowie]

What you describe is how all my cars are. Need choke until temp is about 70C.

I suspect your car is fine.

If you're not happy get a CO meter and measure your exhaust CO. Should be 4 to 5% at idle.

[Iansparky]

My ignition is all new throughout, I am running a filter king set to 2.5 psi, I had no trouble setting oradjusting idle it's just that the jets are so far off the recommended base setting, it just will not run without choke with the jets set at 65 thou. I will check needles and fuel level later

[malcolm]

I recall I set mine at about 75 thou. Again, it needed fast idle until warmed up properly. Ran beautifully, and returned about 22 mpg. Was also one of the faster (standard) E's at Goodwood. Plugs always a bit black'ish but seemed to like it.

[Iansparky]

I have checked the needles they are all um and set correctly, fuel level looks quite low down in the jets, its hard to measure it really if I blow into the jet the fuel bobs about at a guess I would say about 1/4 down from the bridge, maybe I need to check the floats are set to 7/16

[abowie]

it's just that the jets are so far off the recommended base setting

The base setting is just that. A starting point.

Jets at 110 thou, while maybe a little low, aren't completely out of the ballpark.

The only way you can be sure is to measure your exhaust.