Quote:

The following is pirated directly from a post by Eddie Rattley [Ratdat] on Automotive Helper.com He was responding to a question about the J18 engine, but it relates to the A series engine in the big picture.

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The J18 is an overhead valve four cylinder engine that's the last development of the J series engine. That first appeared in the Datsun 411 in 1966 in 1300cc form (J13). The J series engine is devoped from Datsun's earlier E1 engine fitted to the Datsun 312 and 410.
The E1 is basically an Austin/ Morris B series engine but Japanese built. Datsun built Austin A40 Somersets and A55 Cambridges in Japan under licence from Austin and continued to use the engine in their own cars for some time afterward as they did not posses the funds to develop their own engine.
The J series comes as a J13,J15 and J16. The J18, I believe was only used in Mexico to my knowledge although I could be wrong.
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The Nissan A series was a clean sheet of paper design.
The Nissan A series has an external oil pump, a cam on the right side of the block. The timing case extends down the front face of the block & forms part of the oil pan sealing surface, the cylinder head is an 8 port design & the ports do not weave between the pushrods. The fuel pump is on right side of the engine.

The J series has two stamped steel covers for access to the tappet chambers under the manifolds. [see picture]
Only the British could design an OHV engine & still manage to put the fuel pump under the exhaust manifold to ensure that it vapour locks. [The fuel pump is driven directly from the cam which is on the manifold side of the block.]



The photo shows an original J series in a P510 instalation Note that the post initially refers to this as an A series but this is corrected in a subsequent post.
Those of us that are familiar with the BMC engine will recognise the thermostat housing arrangement immediately.

There is no similarity between the Austin/E1/J series engines & the Nissan A series design, other than the basic OHV, upright, inline, 4 cyl configuration.