The Stovebolt Site Forums The Shop Area Engine Shop Please explain these holes in my block

Back again for more advice. Before I install the oil pan on my '54 235 I would like to tap the 2 bolt holes on the lower timeing cover and install studs. Can someone please tell me what the best tap size to use as it seems the tap will also run through the backing plate. Also, what is the function of the other 2 holes in the block above the lower timeing cover bolts? They are drilled at a 45 degree angle. Are these vents or ports to oil the timing gears? If thats the case is it normal for the timing cover to fill up with a small amount of oil? Thanks!

those are oil ports...the drill size etc. is in tech tips i believe, or try the search feature..i did mine, real simple but don't remember size..

Hy Metrinut, I believe the holes should tap 3/8" N.C. , the two holes at an angle are the oil drain back holes from the timing cover area, hope that helps.

Thank you. It does help as the deeper I get into this old truck the more questions I have. Although I am still baffled on the drain back holes since they are well above the bottom of the timing cover. Does the timing cover hold a bit of oil?

Metricnut, you are correct, the timing cover does hold a small amount of oil. I believe the intent was to give the timing chain and gears better lubrication both on startup and while running.

Metricnut,

Your engine should have a nozzle above the timing gears that squirts oil onto them. The angled holes you are looking at in the bottom allow this oil to drain back to the crankcase.

Stuart

Ahhh! that explains it. Their is a nozzle above the timing gear but it was pinched off by the engine builder. Should the nozzle be fully or partly opened?

Metricnut,

The nozzle is pinched off.....by the factory! It was the best way to seal the end. The orifice is near the end pointing down. I think the book says it can be up to 30&deg to the left, or pointing more toward the cam gear.

Stuart