How do you tap into (1 Viewer)

[ScottFJ40]

the fuse box for a power supply. I am looking for a 12v power supply for my hei. How do you guys tap into the fusebox. Sorry for the noobish question, I am an electrical moron.

 

[Pin_Head]

Best way would be to run it off the stock key-on "engine" fuse circuit. This circuit is the wires that are black with a yellow stripe that originally ran to the coil, idle solenoid, VSV, etc.

 

[Vortec_Cruiser]

Your fuse block will have two male spade fittings on the front side. One is for keyed-power, and the other is constant power. You may have to unbolt the fuse block from the pillar to see the fittings. :

 

[woody]

I've used both of those spade fittings for external fuse blocks with great success....

But the black/yellow stripe wire is what connects to your HEI coil input. This is not only run-hot but also start-hot, which is important.

 

[Webster]

When you say start-hot you mean while cranking,correct?
I am doing a TBI conversion and am trying to find the correct wire that is hot while on/running/cranking.

 

[woody]

yeppers....hot while cranking....and that's the black-yellow wire in the Cruiser harness.

See the tech section/Chev swaps for some TBI 350 wire diagrams I just linked up today....

 

[ScottFJ40]

Thanks once again guys for your comments and suggestions. I have to buy a multimeter I guess.

 

[Degnol]

Scott,
Another suggestion would be to use your existing ignition-on wire in the stock loom and instead of running it straight to your HEI (it's too small) run it to a 30 amp relay that draws it's power straight from the battery. Then run a 10ga wire from the relay to the HEI. The HEI calls for a 10 ga wire. However I did wire mine direct, with no problems....yet. But I plan on wiring in the relay.
I'm still a "Rookie" so somebody please grade my paper. Seriously
Ed Long

 

[woody]

I did the relay on my carbed 350 for a while...there was no seat-of-the-pants difference at all. On my TBI350 install, I just used the wire direct.

 

[72cruiser]

hey guys,

i just finished my HEI (and in a hurry so i could actually go home over spring break, ha ha). i haven't done the fuse/relay thing yet.

could someone explain to me how and why for this? i'd be real grateful, esp. b/c i have no electrical experience whatsoever.

thanks,
jonathan

 

[Degnol]

Like I said, no problems with it wired direct, yet, but my experience with automotive wiring is, the bigger the better, with the appropriate fuse and/or relay. I don't think it is as much a performance issue as it is a safety issue. If GM calls for a 10ga wire, believe me they're not going to specify a wire any larger then necessary. IMHO
Ed Long
I hate electrical fires, they're so very....well...stinky and they fry a lot of sh*t