Jowett Javelin Valve Adjustment Question

A short video asking for help figuring out how to properly measure the gap when adjusting the valves on my Jowett Javelin.
I have turned the engine 360° past where the valve is fully open, and there is no gap, unless I push back on the pushrod, at which point the gap is quite large, something like 0.080 (!) or more.
My assumption is that all of the slack on the pushrod should be taken up, before measuring but I figured I would ask before assuming, so please point me in the right direction!

[@stewart9723]

They have hydraulic tappets way advanced at that time , they sold the patent to Rolls Royce . I know this because I use to two people who worked there, including my mum in the offices.

[@TomRymes]

Thank you, Stewart. My understanding is that the Jowetts used Lockheed hydraulic tappets, which were licensed from an American company - it’s just unclear which one.

[@jonnybottle]

Has the engine got hydraulic tappets? Some Javelin engines had them.

[@TomRymes]

It does. After I found this video, I eventually determined that there was a washer that was interfering with one of the pushrods. This caused the push rod to get bent, and that was what was making all the noise.

[@promerops]

@@TomRymes I'm glad you've found the problem :-)

[@TomRymes]

@@promerops thanks. Then again, it’s still not precisely quiet, either.