186p chasing info

[Marza69]

Hi, i found some markings on the back of my 186p block, just wondering if it's the builders marking or something else?
It's (R 1 5 Y )
Any info would be much appreciated

 

[Jolls]

The marking on the back of the block is usually the casting date.

The first character (letter) is the month A = Jan M is Dec (I is not used tp prevent confusion with 1.
The second two characters refer to the day of the month - eg 15th.
The final character refers to the year and should be a number - 0-9. The decade can be determiuned from the engine number.

My guess is that the R is probably a B and the Y is probably a 4.

I trust this helps and is correct for what you are showing.

 

[DavesSV6Tonner]

The cast date on the old Holden red 6 is on the side of the block near the oil filter and is cast into the block not stamped.
The number code B15Y stamped into the rear of the block will most likely be put there by an engine reconditioner long after the engine left GMH.