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Ah.... the ole oil in the cylinder trick. There's a caveat to this, IMO...... actually, several!
One... the oil volume alone will raise the cylinder pressure all by itself, because it occupies space/volume.
To do this accurately and for a comparison....., the same quantity of oil must be added to each cylinder.
Then there's the V engine and/or slant six.
Oil in the cylinder of a V engine will tend to pool at the low point of the cylinder, rendering an uneven wetting of the ring landing.
Then you add into the mix, the full dished pistons that we typically find in the OEM SBC today.
How much oil ends up in the dish, and not at/on the ring landing???
While it sounds like a good science, it's not always so.
I think the where this originated was back in the days of the vertical cylinder in-line engines and flat top pistons.
In that case, the oil test may have proved to be more beneficial and accurate.
When we carry this over to the V engine and dished pistons, the results may not be the same.
Just say'n!
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