Thank you, Jon, for your further advice. Poster Phak1 also noted the voltage draw above. Your advice seconds that. This high voltage draw is a new thing that I learned from these postings. My original reason for adding the terminal block was that I was running out of length of screw on the ignition switch (aftermarket bought in 1977) to add more accessories, but I've now learned that all of those added draws can over burden the switch. In the last few years I have added an electric fuel pump, reverse lights, and the wiring for an overdrive. These three things are now powered from the terminal block. The HEI (when I install it) will be powered also from that block, and I will move the fan motor to it.

If I correctly understand what I am learning, people are using 30/40 amp relays just for their HEI units. I was thinking I should use a 50 amp relay to power the terminal block. I could also leave the terminal block as is and add a 30/40 amp relay for the HEI after the terminal block just for the HEI. Does anyone have advice on that?

I bought a 1978 C20 new. The odometer quit working at 385K miles maybe 10 years ago. I figure it now has well over 400K miles on it. The HEI on that has that very high mileage engine starting easily and purring nicely. I look forward to having that same service for my 1958 270.

1950 GMC 100 Panel Truck, 1958 270,
3-spd Saginaw with BW OD,
3.73 12 Bolt Differential from a 1966 C10,
Front Disc Brakes
Bought it in pieces 9-1976, driving since 6-1978
Follow in the DITY