HEI relay install.(PIC'S)

[BobbyK]

I installed a relay to power up my HEI today.
Pretty easy install.
I also installed a relay for my heated o2 sensor.
Here are a couple pic's.
ALL the pic's can be viewed HERE

The relays I used.rated at 40 amps.They are DPDT(Double Pole Double Throw) relays.$3.00 each at my local electronics wharehouse.


Ran these wire from a existing IGN. splice at the IGN. switch to trigger the relays on.


Here is the splice I had made at the IGN. switch(kinda hard to see)


I replace my existing 1 wire o2 sensor with a 3 wire(heated) o2 sensor.Here is the retrofit harness.


Here's the new 3 wire o2 sensor installed in the drivers exhaust manifold.


This is the power feed to the relays.Red goes to the HEI relay(12g wire).Blue goes to the o2 sensor relay(12g wire).
The circuit is protected by a 16g fusable link(light blue wire).


All hooked up now.


Here's the voltage now being sent to my HEI coil 14.12volts.
Should produce a nice arc!


Took me an afternoon to do this project (pissed around alot though) and maybe $10.00 in materials.

[Cethern]

Very cool what you did there Bob, But why use two relays? for back up? or just to take up part of the load?

Ceth

[BobbyK]

The 2nd relay is for my 3 wire o2 sensor.
I wired them up at the same time.That's the only reason I included it in this post.
Sorry to confuse anybody.

[Russell]

Not too sure I understand why you needed the relays, what are you trying to achieve with them?

[flip66]

sounds like good way to ensure a constant 12+ volts to the dist

[Cethern]

Book Antiqua Well I re-read your posting and it was there but I was looking at the pic's more than text
I wanted to ask you why you use the old style Alt Bracket and not the newer style.


Ceth

[BobbyK]

Russell,I used relays to get full power to my HEI.
14V compared to 12V is alot when your talking about the performance of a coil.

I've rewired my truck the way MAD electrical suggests.http://www.madelectrical.com/electrical-tech.shtml
I've read the site back to front and it has educated me greatly.

I'm trying to isolate all the high load accessories and run those circuits with relays.All high load circuits will be fed by a power distribution block on my firewall.
This distribution block is monitored by the "sense" wire of the alt.This way all high amp draw circuits go through the distribution block and the alt will compensate for the load via the "sense" wire.

I'm trying to avoid the deaded "voltage drop".
It's a little safer method of supplying power to High amp draw circuits.

[FRENCHBLUE72]

Thank's for the mad link it look's like I have some reading a head of me....

[kbs71]

I have rewired most of my under hood electrics after reading everything on the MAD site. Rewired to a internal altenator. Installed relays for my HEI, electric fans, electric water pump, and HID headlights (HI & LOW beams). Love the way everything has turned out and most all of my electrical problems have vanished.

[fatfords]

BobbyK,
It looks like you got the results you were looking for. One question/comment about the fusible link in picture 6. If your O2 senser shorts to ground, the 16 awg blue wire will act as the fusible link (assuming the other wiring in the circuit is larger than 16 awg). If the HEI shorts to ground, the light blue wire may not act as a fuse as it is the same size as the red wire.
I'm not trying to rag on your design (and maybe I don't understand what you're trying to do) but it may be worth a second look so you don't let the smoke out!
Good Luck!

[BobbyK]

The size of the red and blue wires are deceiving.
The red is 12g,the dark blue is also 12g.The insulation on the dark blue wire isn't as thick as the red wire.(cheap wire).

So I figured that the 16g fusable link will protect either of those 12g circuits adequately.

I see what you mean if the darker blue wire was smaller than the fusable link.