differences in standard blocks?

[JonE]

I remember someone suggesting about relieving the block obstruction in the inlet port. This one doesnt seem to be that obstructing (well, in terms of what can be removed and still leave some metal for the stud above), so I wonder whether there are differences generally in blocks and what they might be. There seem to be some evidence of stamping but I cant work out a date.

[bob46320]

is that a manifold face hewn from coal ? or is it an early steam powered version ?

[Reckless Rat]

Earlier blocks had screw-in core plugs. I think the knock-in ones came post 1930. There may also be a serial number (same as the engine n° if it's not been changed) stamped in the valve chest area, towards the front.

[AustinWood]

On my blocks the engine number is stamped on the valve chest gasket sealing surface. Underneath what looks like Red Hermetite on you block.
When I modified the block for my Nippy most of the work was straightening out the ports on either side. I just cleaned up the area around the head stud and made sure the stud didn't protrude.

[Stuart Giles]

Really not a good idea to have to have a length of threaded stud hanging down into the port, but most of the flow restriction on inlet ports is the so called "short side radius" i.e.the bit at the top of the inlet port where it meets the valve throat. This is pretty well a sharp right angle on A7 blocks from the factory. It's well worth putting an actual radius on this part of the port to improve gas flow.

[JonE]

gosh, yes, on searching, an engine number-like number! 159something.
In fact, lots of numbers in various places. Wonder what the other ones mean on the cylindrical bits on the other side?
I'll sort the short side radiuses...! thankyou all