Can I use the block drain for a temp sender?
Interesting. Is there a thread on this? can the sensors function stand alone like just a warning light?
I would think so. The GM knock sensor is just 1-wire (blue) which runs up to the knock module on a bracket on the intake manifold. Sig- is ground. You can find wiring diagram for the module (try Megasquirt site). As I recall, it outputs an on/off 5 V signal that is high when sensing knock. I plan to use w/ a Holley Commander 950, but no reason you couldn't just light a dash LED. The sensor is just a piezo-electric quartz crystal (like a "crystal" microphone), presumably with a weight tuned to resonate when the engine is knocking. Some have to tried to figure out the various GM PN's and worry if a six cyl or even Mopar/Ford V-8 would sense the same. I recall the conclusion is that GM used the same PN for V-6 and V-8 and they just varied by year or whatever, so "should work". They are all push-rod engines, so should sound similar. Holley's algorithm just keeps increasing the spark (within limits) until it senses knock, immediately jumps back ~2 deg, then starts creeping up again. I expect most factory engine controllers did similar, so it is always finding the sweet spot for any cheap gas you put in your ride. SAE papers I read in the early 1980's (when developing such) said a little knock actually improved combustion (efficiency and power). By the time the driver hears pinging, it isn't "minor". Thus, I expect they are designed to always allow knock just below a threshold.
While picking GM, grab the 8-pin HEI module inside the "small cap" distributor, the pickup cable (snip), unplug the cable to the coil, grab the coil and power/tach cable (snip). You can connect the module to a Mopar e-distributor pickup (2 ways, only 1 sparks best). TrailBeast here kits those parts (HEI, not knock) if willing to pay a lot more to avoid a junkyard.
