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can anyone tell me what grade-shade of iron is used for the a series?
for the cylinder head and for the block

regards
baptiste

Sorry, dont know the answer, but interested to know why ?

Does this help?

Gob smacked, only on here would someone know this……

Same here exminiman! But looking at the spec from an engineering but non-metallurgists eye, it is so broad that you could safely say that any mid range grey cast iron would suffice.

As a hobbyist knifesmith... and car guy.

That's simply an amazing piece of historical tidbit.

Exminiman wrote: ↑Sat Apr 15, 2023 4:21 am Sorry, dont know the answer, but interested to know why ?

no problem.
The aim would be to be able to carry out repairs and manufacture some parts.

If a block hasn't been skimmed yet the top of it will have a little dimond shape on it with a number in it. The number indicates the grade of the casting, as according to BMC. The pistons were available to suit the blocks and also have the grade indication on them. The most common is 3

Toby wrote: ↑Fri May 05, 2023 11:43 am If a block hasn't been skimmed yet the top of it will have a little dimond shape on it with a number in it. The number indicates the grade of the casting, as according to BMC. The pistons were available to suit the blocks and also have the grade indication on them. The most common is 3

Really ....seen the diamond shape had no idea there was a tie in with the pistons.

So was this diamond in relation to accuracy of the machining, quality of casting or something else ....just trying to understand why it would matter.

From what I understand it would be an indication of the casting quality.

The numbers in the diamonds on the the top of the block are a size grade for the bores .
Basically they couldn’t make all the bores and pistons the same size , so they were graded and selectively assembled.
The piston grade is normally stamped on to of pistons on a BMC part .
They did the same thing with A+ crank main housings, they had colour coded bearings

Wonderful knowledge...

So, almost a form of blueprinting, tolerance matching, whatever…..?

Suppose its logical as they wouldn’t be measuring pistons and boring to suit…it would be matching a line of pre-bored blocks to stock pistons……

Fascinating insight, thanks for sharing

Examples of the stamps