[Stroker Ace Ventura]

So, my son's '75 El Camino passenger head has this sensor in it at the rear against the firewall. 350/4bbl Cali car, numbers matching verified LM1. I have not seen anything like this in a gen-1 sbc cylinder head...

The part with the wire and the blue terminal cover on it is what we're stumped on. Any ideas?!?

Passenger side pad stamping for ID...

 

[Midmo Joe]

My guess would be a temp gauge, but I don’t think there is any coolant passage there? Wouldn’t hurt to verify the cylinder head casting number. Chevelle.com has an excellent tech section, might be some kind of Calif emission deal.

 

[Stroker Ace Ventura]

@Midmo Joe yeah, that was my thought too... The head boss/shoulder where that sensor is has a bulge not like any other head I've seen... We'll pull a cover and get the #s off and look. I'll post up the findings. Thanks for the info!!

 

[Stroker Ace Ventura]

@bruinfan1966 without pulling a rocker cover, any ideas on this sensor? Figured you've seen your share of cylinder heads in your day...

 

[Stroker Ace Ventura]

Mystery solved... My kid was in his Chevelle/ElCamino forum and some old salts knew right away. It's GM's crude attempt at a knock sensor used to shut off the A/C if detonation occurred while running. Simple and probably less than effective. His Elky has factory A/C so it makes sense...