Carburetor Issues in a 1961 Rolls Royce Silver Cloud II

In this video we replace the carburetor main jet and diaphragm assembly and synchronize the butterfly valves. Details are included on the updated piping between the float bowl and the chamber below the main jets, and the associated new spring that is now included. The new jets are significantly tighter on the mixture needles that the old, worn ones. As a result, the new main jets had to be adjusted down (away from the pistons) compared to where the old ones were just to get the engine to start. We also create a new gasket to seal the joint between the carburetor and the manifold to eliminate leaks there. These changes made a significant improvement in the idling performance.

[@wrf2412]

Hey John. Just stumbled on your Cloud II series - thanks for showing the SU diaphragm replacement. I have a ‘59 S1 which has the last of the Rolls six cylinder and the slightly larger SU HD8s. This was helpful to see despite the differences between the models.
There are some really good videos of Ronny Shaver from the RROC (rollsroycenut) and others out there. But glad to hear you name drop Albers - you’re in the right spot

[@johnsworkshop3312]

Thanks for your feedback. I too like the Ronnie’s Garage series. Lots of good information there. Thank you.

[@wrf2412]

@@johnsworkshop3312 Hey John - follow up question. Now that you have the replacement diaphragms installed, did you notice the car running better/leaner? Now that the clearance on the jet is a tighter fit, did you find that it would bind?
I'm debating whether to do this on my S1 because I've noticed adjusting the set screw doesn't do much, but fortunately I've gotten it to a point where it is idling fine (plugs look fine and the automatic choke works as it should). The eternal question of whether to fix it, or will it open up new problems....

[@johnsworkshop3312]

Thanks for the feedback. Glad they were helpful. Ronny sure has a great repository of information!!

[@johnsworkshop3312]

Yes - that made a huge difference. We did have to lower the main jet by a turn or two to avoid the sticking to which you refer. Then it would not start it was so lean. At this point we have the jets adjusted all the way down and it is still too lean. The next step is to raise the needles in the pistons to see if that gets us to the correct mixture.

[@ashleyenders1831]

Nice video!

[@johnsworkshop3312]

Thank you!