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I recently sold my 997 project due to loss of shop space. I know the block had 1000 cast into the back side. I have located another 997 project less power unit. Seller has a 998 power unit he says will pass for 997. Are or were there ever 998s with 1000 cast into the rear side? Thanks Steve (CTR)

The early 997 blocks had 1000 cast into the back of the block. They were 12A204 blocks which was cast into the block under the 1000. At some point (I want to say in the middle of 1963) the block casting changed from 12A204 to 12A497. The 1000 was no longer cast into the block and an Aluminum tag was now used with 1000 stamped into it. The 12A497 was cast into the block on the lower back righthand side. The 12A497 block was used for other small bore engines at this time too like the 1098. The 998 Cooper also used the 12A497 block and same 1000 aluminum tag. So it is true that the 998 could be mistaken as a 997 however the internals and cyliner head would be different. The 998 never had 1000 cast into the block. it only had the aluminum tag with 1000 stamped into it.

Hope that helps.

Brian

I think the change point for block castings is somewhere between mid 1962 and early 1963.

A 997 engine did appear for sale on this very forum still with original engine number on , it was the later block with a car build date on Jan 63 from memory.

As with most change points they will probably be no definite answer.

Anyone with an original 997 with un- disturbed original engine number post here

I have a rather early 997 block #2331, so early 62 I imagine.

It just confirms that the 1000 is cast in the early blocks

Excellent

Anybody else got one ?

This one has just been tanked and had the mains line bored, probably a 62 as well. It is going into my June 63, which is supposed to have 9FSAH23515...

swindrum wrote: ↑Tue Dec 07, 2021 7:41 pm I have a rather early 997 block #2331, so early 62 I imagine.

It just confirms that the 1000 is cast in the early blocks

2331 is a Jan 62 engine, and the 5731 number is approx May 62.

That's narrowing it down a bit

SMOKE GREY wrote: ↑Wed Dec 08, 2021 9:48 pm
2331 is a Jan 62 engine, and the 5731 number is approx May 62.

So in 13 months, there were another 17,784 997s made! (Based on my June63 being engine number 23,515) Still none of this really helps determine when the "1000" casting disappeared...

The early 1098 engine had the 850/997 block as well as pinch bolt connecting rods. They went to the 998 block/rods @ early 1963.

Early block to end of 63 and Late Block to 998.
The never used fuel pump mounting also.