I'd bet the regulator for a couple reasons.
1: it's old.
2: it survived my little welding experiment from a while back. Maybe it has an issue associated with that.
Tonight's interesting discovery pertains to the AC system. I noticed recently that the AC compressor wasn't coming on. I remember it did a while back, before the timing chain etc but now, nothing. So tonight I played with it during our break and made a simple discovery. It works. Just not when plugged in. I guess the thing it plugs into is some sort of pressure switch?? Not sure if it's the high or low pressure but I'm left with a couple ideas.
Bad pressure switch? It is strangely rather rusty and probably the original one? I'll have to see how I can test it.
Theory 2 is that somehow it has lost some/all pressure in the system, perhaps when moving the compressor out of the way for the timing chain? I didn't disconnect any AC lines but who knows if one started leaking.
I really hope it's not a loss of coolant/pressure as it's still, as far as I know, running R12. Not cheap to fix or to convert.
What do you guys think? And for those who converted to R134a, how much did you change and how bad was the cost?