By maddog2020 - Sun Aug 14, 2022 1:32 pm
- Sun Aug 14, 2022 1:32 pm
#165949
I learned something interesting today. we all know that the 928 has oiling issues, and that the oil packs in the cylinder heads. I know part of the reason. The drains in the upper block are mismatched to the drains in the lower block (girdle) with the holes in the girdle being smaller than the drain holes in the upper block. these are specifically the drains on the right side of the engine.
The drains in the upper block are approximately 26mm 12mm rectangle with rounded corners. One of the drains is an odd shape and it was too small by 2mm in all directions. The rest of the drain difference ranges between 2-5mm in width and height. One of the holes was 9.5mm by 21.5 ! Most of this is due to core shift when casting the block, but also I think there were some flaws in the castings due to the casting tech at the time. I've got about a day's worth of labor cleaning up all of the casting flaws on the lower girdle. But that is me doing everything by hand except the clearancing for the larger rod caps on my new rods.
The drains in the upper block are approximately 26mm 12mm rectangle with rounded corners. One of the drains is an odd shape and it was too small by 2mm in all directions. The rest of the drain difference ranges between 2-5mm in width and height. One of the holes was 9.5mm by 21.5 ! Most of this is due to core shift when casting the block, but also I think there were some flaws in the castings due to the casting tech at the time. I've got about a day's worth of labor cleaning up all of the casting flaws on the lower girdle. But that is me doing everything by hand except the clearancing for the larger rod caps on my new rods.