R Type 4.5lt

[Al Coutts]

The exhaust valve seat on #6 cyl in my newly acquired engine appears to have lost half of its seat. From the workshop manual, I see no evidence of these being pressed in so wondered what this audience knows.

Thanks,

Al

[John Robins]

I looked at the workshop manual, which doesn’t mention any form of insert in the block as you say, but I cannot see how the type of damage shown in your picture could have occurred other than by an insert breaking up. Do you know any history of the engine? Is there anything stuck on the valve seat?

That is about the limit of what I can offer, sorry.

[Christopher Carnley]

It is a later press in from a reconditioning job. They come loose, are brittle like the 3rd speed thrust washer in the gearbox, and break up under the valve hammer.

You will have to strip the block and have them all re-done preferably by a firm that can nitrogen shrink them.

New exhaust valve guides are also required as the machinist uses these as a pilot for the cutter to maintain concentricity.

[Al Coutts]

Thank you both. Mr C you should enter Mastermind with Bentley mechanicals as your chosen subject!

[Christopher Carnley]