The jury seems to be out on whether the engine used in the P4 100 is identical to the Land Rover 2.6. Some people say it's exactly the same but I've heard others insisting there are differences though not specifying what they are.
Happy thread revival....
The jury is not wrong... the engine I am working on is minus the main bearing cap bolts as well as the big end nuts, among other things, so I whipped samples off a Landy Series 1 2liter engine I am working on for sampleas, and.... they don't match.
The Landy engine main cap bolts are coarse thread, as are the big end cap studs, and the 3 liter engine's are both fine pitch... BUT... the 3 liter IS NOT UNF...and it certainly isn't Metric, which leaves me with Whitworth as a final choice...
BUGGER!!!
This morning's jaunt into town was hilarious, the bloke tasked with supplying me with one each 5/16'' and 3/8'' UNF nuts for testing was getting very cranky when I refused to agree with him that 5/16 was 8mm or that 3/8 was "around 10mm"...
I can't wait to see his reaction when I arrive looking for Whitowrth stuff tomorrow....
Back to the 2.6 engine, the P5 head gasket is identical to the Series 3 2.6 engine, bore is 3.063'' for all P5 and the Landy engines.
Crankshaft journals on the MkIII 3liter are bigger than the earlier MkI & II, however. MkI and II suffix A & B are 2.250'' and MkII suffix C on and MkIII are 2.625''. Big ends/crankpin are 1 7/8'' diameter.
Landy Series 3 109'' engines are 2.624'' mains and 1 7/8'' big end, so same as the later P5 engines.
I don't have P4 specs to hand as a comparison, sorry.