Amazing and detailed replies. Thank you!!
I put a gauge on it, and at top speed on the drill most I can get is 12 PSI. Oil just starting to barely dribble into the rocker shaft and out of the return pipe in the supply tube on the rocker. Coincides with your saying valve is opened at 15 PSI. Based on what I'm seeing I'd imagine it starts to open around 8 PSI and is maybe fully open at 15PSI? Though currently there's variables/unknowns to that guesstimate haha
.
Ran the truck with valve cover off and got the same result. Once warmed up the gauge fluctuates a little with a slow dip to about 3 PSI then back to 10-12.
running at fairly high idle (no load) pressure doesn't really increase much. This is with 20w50 dino oil.
I think I'll remove and inspect/replace the distributor valve next, though based on what I've read and now know it seems like 10-12 PSI isn't bad at all for this old girl. have to wonder if replacing the line is going to make a lick of difference.
And we did spray and clean the tube out, though I'm sure doing it a few times isn't going to hurt, so we will take that advice and redo it again in the hope the line is just partially restricted.
other thoughts/ideas:
* Is there any realistic way to replace the line externally on the 216? That was one thought I had. I could drill and mount a fitting into the valve cover and put a flex line on the underside to hook up to the Supply tube on the rocker. Then obviously on the external side it's straightforward, right into the outlet of the Distributor valve. In this method I could monitor PSI to the top end separately also.
*Another idea I had was to run a second electric pump (if the issue ends up being not enough volume from stock pump + some bearing wear). This would require some R&D to ensure a low enough volume pump and restriction as needed so the top end doesn't get too much oil, which would be easy to do!
