Spill timing

This 1920's design was the basis for virtually the same engine, whether produced by any of the companies who have traded under the Russell Newbery name, or one of the National Gas and Oil Engine Co. versions of the same basic design and built under licence. It does in fact incorporate 3 separate camshafts within the engine, two housed in the combined cylinder block and crankcase (the 'column', as the makers referred to it) and a third one, referred to as the 'fuel shaft', housed in the timing case and carrying (in the earlier engines) the governor assembly at one end and operating the cooling water circulation pump, the fuel lift pump, and the fuel injection pump via a set of adjustable roller tappets housed in the main timing case casting.

Adjustment of the effective lengths of the fuel injection camshaft roller tappets, as distinct from the non-adjustable injection pump element bucket tappets housed within the injection pump body itself, is NOT "the way RN do the spill timing", it is in fact for the sole purpose of setting up the pump phasing and is the first step in setting up the injection timing. However, as I indicated in one of my earlier posts in this thread, neither 'RN' nor 'National' ever advocated the spill cut-off method for setting the injection timing on these D series engines. The works recommended/approved procedure was by alignment of the injection pump body window and bucket tappet lines/marks in relation to an injection/firing mark on the flywheel rim.

Looking at the engine from the timing case end, the inlet valve camshaft is housed (lengthways) in the lefthand side of the block, the exhaust valve camshaft is housed (lengthways) in the righthand side of the block, and the 'fuel shaft' is housed transversely, in the upper part of the timing case, and driven via a skew gear on a (rotationally) adjustable hub mounted on, and behind, the exhaust camshaft chainwheel.

This design and layout is somewhat unusual in that it results in an 'in line' injection pump minus the usual integral camshaft, or bolt-on cambox housed camshaft as utilized on Gardners (LK, LW, LX, L3, L3B etc) with same CAV or Bryce injection pump body as those found on Nationals and RNs. It also means, of course, that the pump phasing on a National or an RN cannot be set-up other than with the pump installed on the engine, and you will need to amend the advice you gave in your recent post on CWDF - ie - "get the pump to a specialist of checking and adjusting so the phasing & calibration is correct . . . ".

With regard to the possibility of pump element plunger and delivery valve damage resulting from someone messing about with the roller tappet length adjustment, I did warn 'linnet' about this in my initial response to his question, but I'm not at all sure that he understood the point that was being made. In view of him saying the engine is running alright with no apparent problems at present, perhaps we should both repeat that warning, and at the same time emphasize the wisdom of refraining from attempts to fix things that aren't broken, and correctly identifying the fault giving rise to any particular symptom, such as 'knocking, BEFORE getting the spanners out ! 

I agree that the 'knock' which prompted him to begin his ill-advised tinkering in the first place would have been attributable to something other than over advanced injection timing, but as the fault, whatever it was, seems to have cleared itself and not returned, he would again be well advised to leave things alone unless and until the fault does recur, and can be correctly identified.