Appologizes for the double post, but I need the thread to get more exposure. The board is quiet anyway
So I filled up the fuel tank last night and started having some low end detonation trouble. I think I might be the victim of bad fuel. I also discovered that the J&S wasn't retarding timing with the check valve on its vacuum line, despite J&S telling me this wouldn't disable the knock detector in the unit.
Now the car is idling at 700 rpm. The car is pulling its normal amount of vacuum. The engine starts fine. When the radiator fan or air conditioning is on, the idle raises to the normal 800 rpm. When both are off, it drops back down to 700 rpm. The car is not smoking at all. I pulled the oil cap while the car was running, no smoke at all. Power seems fine. I'm having to pull alot more timing in the low rpm range since filling up with this tank of fuel.
I'm of course going to do a compression check right when I get home tonight.
Other than a blown piston, anyone have an idea of what might be going on?