mk1 square four . oil issues

[DaveH]

I'm a bit reluctant to re-open this controversy, but it seems not to have been settled. I came across the issue while looking for insight on the abnormally low oil pressure my 1952 Mk I Square Four exhibits.

Apparently several owners have had inexplicable low pressure, and solved it by switching the two feed pipes so the smaller 1/8" pipe feeds the rockers - throttling delivery there, and raising system pressure. Others claim the original Mk I assembly routed the small pipe to the gauge. Some observations:

- Most installations seem to have the large pipe to the rockers, including mine (which looks old / original, but who knows?). It seems more likely this was the factory setup - why run a larger pipe most of the way to the gauge, then a smaller 1/8" pipe from the junction to the gauge? Simpler and cheaper to just use two 1/8" pipes all the way. It would also be an odd way to meter flow - other designs I've seen use a jet or equivalent to do this.

- Draganfly makes their pipes in-house, so has made a decision on the factory configuration. Their photo of the Mk I assembly (5172-49) shows the small pipe to the gauge.

So my impression is that the original pipes had the small pipe to the gauge. If so, and one still has low oil pressure, one has to assume there is another issue - not all Square Fours from the factory had this problem.

I'm wondering if 5178-37, the rocker oil feed stud, might be a factor? Using a small hole in this would have been a sensible way to meter the flow to the rockers, and possibly later reproductions were made with a larger hole. My own stud is non-original.

Does anyone know the number and diameter of the holes in an original oil feed stud?

Thanks,

Dave

[DaveH]

Another bit of data: I queried Draganfly, who make their 4G pipes with the small one to the rockers, but Mark I pipes with the large one to the rockers.
They replied "we are confident the parts are correct to OEM specifications"

[allan.walker]

I suppose that you have seen viewtopic.php?t=13233

A possible reason for low oil pressure.