stina said:ERC 0216 is the number for SD1 heads , Do yours have single or double valve springs ?
stina said:Single valve springs are SD1 Mike , Double springs equal P5/P6 heads .
The advantage of early SD1 heads over P6 is larger valves , harder valve seats , better breathing . I know people will now say how much better 10 bolt heads and other alternatives are but if you have SD1 heads and you just want a nice usable road engine then you have a good starting point i guess
Ps long reach plugs in SD1 heads , short reach in P6
SydneyRoverP6B said:Hi Mike,
The thread length on the spark plug will confirm the type of head, no need to remove the rocker, unless you wish to know whether it has single or double valve springs. The early heads can have their double valve springs replaced with single valve springs.
Ron.
SydneyRoverP6B said:The P6B heads have threads for the plugs some 12mm in depth, all others are 19mm. In both cases, the electrode will just protrude into the combustion chamber.
testrider said:SydneyRoverP6B said:The P6B heads have threads for the plugs some 12mm in depth, all others are 19mm. In both cases, the electrode will just protrude into the combustion chamber.
So if Mike measures the depth of the spark plug hole on his engine with a bit of wire that will identify which 'heads they are.
SydneyRoverP6B said:It is an 'O' ring on the end of each cold start valve, and ideally you should replace them. I am pretty sure that my replacement 'O' rings came with the kits that I purchased. You could always go to a bearing supplier of similar and have them match the 'O' rings. Fuel resistant nitrile is what you're after.
SydneyRoverP6B said:On the subject of needles, what did you have in mind? There seems to be a propensity to fit excessively rich needles into engines there in the U.K. If the fuel contains ethanol, then that would be a reasonable explanation, if not then apart from engine damage through bore wash, power will also be lost.
The original BBG or BBV needles within the HIF6 carburettors are almost perfect when delivering the correct air/fuel ratio at the top end. I know this from having an air/fuel ratio printout of my Rover's original engine, which I'll put up shortly within the thread I started within the engine section. If you fit better flowing air filters, then the needles will need changing, but the difference will be minimal.
Ron.