Hello all
I have discovered this fantastic forum and I have already learned a lot from it. I hope I can do a humble contribution with my messages.
I am the proud owner of an XK120 FHC from 1952 (679882), since this summer.
Even if the car is matching numbers (engine is W5572-8), my current cylinder head is earlier than my car (W3423-7). (This head actually belonging to 679050, information found on from XKdata.com). Unfortunately this head is so old that I cannot put straight 3/8 cam lift on it.
I bought the famous book from Des Hammill that I have just started reading.
My understanding is that a XJ6 3.4 S3 would be the most powerful cylinder head to use.
My questions to you:
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Does the XJ6 3.4 S3 also has the big valves (like the XJ6 4.2 S3, but apparently this one wouldnāt work as the cylinder spacing is different)?
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Is the inlet manifold also straight port even if it has only 2 carbs originally? Would it then be the best manifold to fit with my twin HS8 carbs? (I have already bought these carbs)
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What would be the loss of performance compared to a Triple set of HS8 with a triple carb manifold? (Ideally I donāt want to fit a triple carb set in my XK120 bonnet as I think itās too crowed and it is needed to cut inside the wing, but maybe I am wrong).
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I hope that the modifications needed on the XJ6 S3 head are feasible without too much trouble. My understanding is: Closing the 2 cooling holes - Adapting the old cam covers to keep the old look - Adapting the mechanical drive tachometer to keep my old tachometer - Adapting the cooling system/cooling hoses to keep my original thermostat/thermostat hose/radiator/temperature probe.
Many thanks in advance for your wise answers.