I'm trying to diagnose a few things on my 75 280z 2+2, and I'm wondering if they might be related. Any help would be appreciated. Also, does anyone know why the section of my camshaft above cylinder #2 is red? Video.
In summary, I can't seem to get power out of my engine. It used to run "great", but now I can barely get the car over 30mph.
I ran a compression test, fearing a blown head gasket, but though the readings aren't great, I would have expected to get over 30mph with them (1: 170, 2: 156, 3: 167, 4: 169, 5: 160, 6: 165). That #2 cylinder seemed especially low, so I ran it with a tsp of oil in the cylinder, and no change - still 156.
My vacuum is measuring low at about 13 in of Hg. I replaced all the old vacuum tubing, but it's still running low, even with most subsystems' vacuum lines blocked off.
Fuel is spraying well out of all injectors.
Fuel pressure is at 38 psi with the fuel pump on, but engine off, then drops down to ~30 psi when idling.
Using a timing light, I adjusted the distributor til the engine was at exactly 10 degrees by the timing mark.
I lashed the valves back in the day at cold, but I definitely hear a clicking from the engine that I don't love. Based on that and everything above, I imagined that I must have just screwed up the lash, so I opened the valve cover and checked, but no, the lash was exactly where I left it.
So I don't know. Any pointers, ideas, or other debug steps would be appreciated. And yeah, if anyone knows why that section is red on the camshaft, I'd love to know! Thanks everyone.
Valves in action