Here's what we're dealing with...the topside of the M117 engine with its CIS-E fuel injection system. This view is front-to-rear, with the distributor at the bottom of the photo and the firewall at the top. Pardon the filth and rust...I'll get to those tasks someday. The TVS is located in a hole as pointed to by the arrow. You can't reach it until the Mixture Control Unit (MCU) & Air Guide is removed.



Here's a close-up with the partially-visible yet dirt-encrusted TVS highlighted in red.