I don't know if the QV valves are sodium filled, I know the exhaust valves of the Jalpa are.
In general it's not necessary to have sodium filled valves in an aspirated engine, for charged engines it's necessary but not for aspirated.

You can use eigther the mercury or the unisys or both, we used both...

The valves will not touch the piston unless you exceed 8000rpm by far or a springe is broken and the valve falls into the chamber at the wrong time.

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RaymondQV
Countach QV Ex-Mimran #GLA12997, Urraco P300 #20530 sold in August 2008, Jalpa #FLA12203 sold in May 2006
www.countach.ch
www.jalpa.ch

When Frank Sinatra got his Miura S in 1970, he said: “If you wanna be someone, buy Ferrari - If you are someone, you own a Lamborghini”.

Definately get rid of Sodium Valves in the older engnies, they are very poor quality and WILL break just like in 911 engines, but costing far more to repair the damage in a Ferrari or Lamborghini engine!!!

Are the chain tensioners hydraulic or mechanical? And how often do they need attention?

Is the block magnesium?

Your rebuild pictures have peaked my interest.

the chain tensioners are mechanical, the block is aluminium.

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RaymondQV
Countach QV Ex-Mimran #GLA12997, Urraco P300 #20530 sold in August 2008, Jalpa #FLA12203 sold in May 2006
www.countach.ch
www.jalpa.ch

When Frank Sinatra got his Miura S in 1970, he said: “If you wanna be someone, buy Ferrari - If you are someone, you own a Lamborghini”.

Is there a rev limiter in the distributor? and can you service tensioners with engine in car?

Hope car is running ok. Sure looks good!!

The rev limiter is on the ignition box, yes the tensioners can be serviced in the car, not a big job.

Rev Limiter refer also to this thread:
MSD Ignition Countach

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RaymondQV
Countach QV Ex-Mimran #GLA12997, Urraco P300 #20530 sold in August 2008, Jalpa #FLA12203 sold in May 2006
www.countach.ch
www.jalpa.ch

When Frank Sinatra got his Miura S in 1970, he said: “If you wanna be someone, buy Ferrari - If you are someone, you own a Lamborghini”.

Does the engine use a forged or cast crank and are the cam lobes adjustable?

The picture of the engine just before installation is impressive.

The crank is turned out from a almost 100Kg billet.
What do you mean with adjustable?
It's not adjustable during driving in sense of a variocam but you can adjust them to OT, I think this picture answers your question:

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RaymondQV
Countach QV Ex-Mimran #GLA12997, Urraco P300 #20530 sold in August 2008, Jalpa #FLA12203 sold in May 2006
www.countach.ch
www.jalpa.ch

When Frank Sinatra got his Miura S in 1970, he said: “If you wanna be someone, buy Ferrari - If you are someone, you own a Lamborghini”.

Sorry, what do you mean by OT? Also usually the rev sensor alongside the ignition box also drives the tach...is this so?

Here the difference between an original:



and a recored radiator:



The recored has a narrower net and should perform much better, I will know in a few days when it's installed in my car...

__________________
RaymondQV
Countach QV Ex-Mimran #GLA12997, Urraco P300 #20530 sold in August 2008, Jalpa #FLA12203 sold in May 2006
www.countach.ch
www.jalpa.ch

When Frank Sinatra got his Miura S in 1970, he said: “If you wanna be someone, buy Ferrari - If you are someone, you own a Lamborghini”.