HEI Conversion-Sudden Death

[RustyPile]

Originally Posted by 67carry-all

...........<snip>..You've convinced me to ditch the relay set-up and simplify the 12V feed to the HEI. I'll get the Packard connector ordered and hopefully have it in time for a brief weekend project...<snip>...............

Why "order" the terminals.. The shipping will cost more than the terminals. Any parts store worth it's salt will have them in stock.. A package of 10 costs me $3.50 at my local parts store...

[67carry-all]

The tach is a 2 1/6" Autometer, 0-5,000 rpm; I don't recall the model number. It's been installed in the truck for literally years without being hooked up prior to this week, one of many little items that got put on the back burner along with the truck itself while life happened. My son's daily driver died, so the Suburban was pressed back into service. He loves the truck and gets positive comments about it virtually every day. The tach is certainly a non-necessity, but something I'd wanted to add a little interest to the non-gauge instrument panel.

"Any parts store worth it's salt ..." - yeah, about that. Nearest store is about 5 miles away, not sure how much further to find one worth it's salt (most recently, couple of guys at the store that should know better were stumped at my request for a new air cleaner stud). So, for something a little unusual such as a Packard terminal connector, it can be easier from a time and frustration standpoint to order from a reliable on-line vendor.

[67carry-all]

Well, guys, counterpoint from the guy I was ordering some electrical stuff from - his opinion is that the relay to power the HEI is the ideal way to go because it assures a constant 12+V. If I'm understanding him correctly, the power from the bulkhead goes through the ignition switch, as do other power demands such as heater fan and lights. When these are active, the demand is enough that it pulls down the power available to everything running through the ignition switch, and the HEI would therefore see a reduction in voltage. Thoughts?

Since we all like pics, here's one of the tach in question.

[Big Kev-O]

The lights do not go through the ignition switch, if they did you would not be able to turn them on without the key turned. Your ignition switch should be able to handle the load. Swapping out the resistance wire & using the Packard terminal is a clean & reliable way of connecting your HEI. Adding a relay has it's pros & cons. Yes it takes a small load off you ignition switch & provides a strong 12v power source but it also adds another potential point of failure. If you add a relay I recommend keeping a spare in your glove box.

Modern day Chinese made electronics are not exactly dependable. I have purchased 12v relays, ignition switches & headlight switches from auto part store that have failed. The first ignition switch I bought didn't last a month.