S-T ?

Looked at first pic and thought definitely S-T (probably P3, P4 or N). But then the second pic showed an asymmetric shape that I haven't seen before - so none the wiser here I'm afraid.

ISTR only two-stroke Hartop was the rare FE - couldn't tell you what the head looks like though. Oh dear, we're not being much help on this one are we!

Shame. I was relying on you and Kim :-) Hartop has been suggested. Any thoughts anyone? ttfn Roland

Probably P3/4. What's the stud centres?

Regards,

Kim

That's what I thought at first, but don't these have a symmetrical doughnut shape rather than being deeper on one side?

hole centres are 2 3/4". Bore is about 3" and the flat combustion chamber is about 1/2" deep. hth Roland

"Roland and Celia Craven" wrote (snip):-

When I first read the above I had visions of head bolts inside the bore - then I switched my brain on!

No 3" bore AFAIK but P5 and P6 are 2 3/4" . Many variations for different applications so I guess it could be one of these - anybody had a close look at the P5X used by Zwiky (or was it Bowser) for petrol pumps? -- NHH

I've got this sneaky feeling that I've seen a head like this on a P3 or P4 at a rally somewhere. I suspect that it is a quick fix by ST's for use in circumstances where the tank or radiator was very close to the head. The increased space above the exhaust side of the engine might collect enough extra hot water to add a sufficient to the thermo siphon effect to reduce boiling on a hard-worked engine. It is only recently - and from this NG - that I discovered that the relationship between tank or radiator and the engine is important on thermo-siphon systems. The further apart in a vertical plane the better

I was looking at the disposition of the "chin" radiator on Peter Grieve's Merlin the other day. It is a LONG way below the engine to facilitate it being (I assume) in the best place to benefit from prop wash. Obviously, the coolant (Rolls-Royce don't like the nasty cheap word "water!") is pumped, but I did wonder if it would not have been better placed above the engine - but Hell, what do I know, mine are very stationary .............

-- Regards,

Kim