While replacing the head gasket in the engine (1973) of the MGB, I had the rockers sitting on a piece of cardboard while I worked on scraping the carbon off the head, cleaning, and measuring for warp.
The next morning I start work again and notice this plug/bolt laying in the area very near the rocker assembly. I CANNOT find a location that this would go, either in the rocker assembly or the cylinder head... or the carb (webar DGV) for that matter. I poured through the MG Service manuals, and the Moss catalog as well.
Stats:
- it is about 0.6 inches square (about the size of the Spark Plug at the threads!)
- the threads seem worn down
- it was mostly coated in nice clean oil
- it is not brass
- hex socket is for 5/16ths allen wrench
- It's not an air-injector hole plug
- It's not a rocker/valve gap adjustment bolt
Leave a comment if you have any clues to this mystery!!
Is it possible the last owner/mechanic dropped it into the engine at some point and it's been rolling around - that may account for the worn threads - maybe??