What is recommended as a sealant for the joint between the block and cambox -in this instance on a three valve four-cylinder engine. I am using an aluminium closing plate.

Hylomar

Locktite 518 is far better than Hylomar [which I used for 20 odd years] It is remarkably good at sealing.Remember that on a Bugatti engine with screwed in valve guides,they need to be in and stay in their positions after grinding in the valves.The threads are not a very good centering device.

Hylomar is not made for cars , it is for jet-engines.Normal threads are not very good for centering , but if I make them , it is in the center . I grind the valves in place , no need to take the guides off again .

Many thanks for your help.

British engineers invented the jet engine.

Well I never ! and I had always thought that it was an ancient Greek.

first jet engine was made in Greek , over 2000 years ago with steam .Elling in Norway 1903 , de Karavodine in Russia 1906 . I think we all know who made the first successful ones .