What is this thing attached to the lid with 2 screws and do I need it? '77 MGB

[Ian F]

Good to hear from California! My daughter lives in Sacramento.......
Rust probably not a problem for you and you should be able to find everything you need for the B. Lots of used spares available over here, and I assume also in the USA.
All the best
Ian F

[Steef]

It is the "spark advance solenoid", a valve that closes off the vacuum line to the vacuum advance of the distributor. Only in fourth gear is the valve opened by the "spark control switch", so that the ignition time is greatly advanced (up to 12 degrees of distribution!) This is to limit emissions at cruising speed. It has been removed from most cars over time for a variety of reasons.

[Ian F]

Thanks for the explanation, clearly a lot more complexity than I ever imagined.
If it was April 1st I would have found it difficult to take seriously!
Many thanks
Ian F

[AndyC]

Hi, I have fitted some months ago a new brake and clutch reservoir. However the clutch reservoir is constantly leaking through the cap. Is the solution simply a new screw cap or something different? I have tried a thin washer inside and PTFE tape to no avail. A simple journey of 80 to 100 miles reduces the level from max to min. The cap seems to go on tight but overtight and it slips the thread. It's ruining the paintwork!

[Not_Anumber]

Are you certain the fluid is escaping through the thread on the cap and not the grommet where the reservoir fits to the cylinder ?

[Ian F]

You probably need to post this in a new thread with a new title.
However, a photo would be helpful. It's not a common problem. I have found though that several of the white plastic aftermarket caps do not fit and cannot be tightened. I resorted to digging out an old scruffy cap which did fit well. I did get a refund from Moss. Still difficult to see how as much fluid as you say could leak out though?

Ian F

[AndyC]

Are you certain the fluid is escaping through the thread on the cap and not the grommet where the reservoir fits to the cylinder ?

Yes quite sure it's coming from the cap. I wrap a cloth around the reservoir to limit the paint damage and after a journey the cloth is damp and just wiping your finger around the base of the cap gives a fluid covered finger.