HEI wiring questions

[Stocker]

Beautiful truck!

[cjoenny89]

thanks

[davepl]

Wow, I never thought of HEI as a high-draw unit. 30A is quite a bit. I think I'd run an auto-reset breaker rather than a fuse, just since Ignition is one of those "gotta have it" things.

[RichardJ]

>> it momentarily jumps up to 30A and due to the small contacts, that are probably dirty and worn <<

Dirty, worn contacts would increase resistance. If it is still true that E = I x R, then an increase in resistance would cause a decrease in current.

Older, pre HEI Ignition switch's were subject to much greater current when someone turned on the radio with the key ON and the Ign points happened to be in a closed position. Not good for the points and they would usually fail long before the Ign switch.



I suspect the reason Pertronix uses a 30 Amp relay in their kit that you mentioned, is because they are manufactured by the millions and are dirt cheap. Less than $3 in most places.
If you went looking for a 10 or 20 Amp relay, the sources would be much more limited and the price 5 x greater.
That's a good deal for Pertronix. $32 for a $3 relay and a couple of feet of wire. They don't even supply Vaseline.

[davepl]

According to Pertronix (not HEI but a close analog), two interesting things:

1) They're saying an amp per cylinder, basically, and we'd be at 8 amp with an Ignitor III. That's not HEI, but it's similar.

2) Even with a Pertronix they say leaving the key in the ON position can damage it, which I find pretty weird with a solid state ignition.

http://www.pertronix.com/support/tips/