hei dizzy install

[kingswood country]

Hi, I've got an hei Chev style dizzy with the coil on top for the old red 253, I currently run single points system.
Now when I tried to fit it I couldn't get any spark, there are two terminals under the coil on top of the dizzy cap, one for tacho, one for battery. I've changed the ring contact on the power wire to the spade contact to suit and plugged it in and no spark, but afterwards was told I need a relay to get spark there, the instructions aren't very clear at all.and I've been wanting tonput it on for a year and a half. Does anyone have ideas or diagrams or anything at all to help the instal?
Thanks in advance.

 

[ari666]

Yeah man easy fix. The old positive wire will have a resistor on it, so wont have enough oomph to run the hei coil. The relay is just a switch between the battery and the coil. So the two opposite terminals make it work (hope i have my numbers right) 86 is to the battery + 87 to the coil 37(i think) to earth and the left over terminal to the old coil wire.

Ill check the numbers tomorrow

 

[kingswood country]

What are these numbers for? Are they just Numbers on the relay to identify which lead is which?

 

[kingswood country]

And how would I wire it?
There is only two plugs on the coil, one for tach and one for batt, where's the ignition come onto it?

 

[drewVHSS]

What are these numbers for? Are they just Numbers on the relay to identify which lead is which?

Yes they identify which lead is what compared to the diagram on one of the sides.
87 output to load (dizzy)
30 connect to pos terminal from battey (fused please)
85 and 86 are the switching terminals.
Try 85 with the cars original dizzy wire to control the relay and 86 to earth.

Some relays have a diode in them to prevent backfeed, some have a resister. Ford relays are backwards to holden (inc some aftermarket) so when you wire up 85 and 86, keep an eye on it in case the relay prefers to have these two wires around the other way. I've made the mistake of putting in a ford relay from my spare parts bucket only to have the switching wires try to fry... reversed the wires for 85-86 and all was good.

Also, most pts to hei conversions i've done using a relay had a problem of the engine continues to run after you switch the ignition off.
To fix this you'll need a 1/4 watt blocking diode (dick smith or jaycar will have these cheap, dont goto an auto electrician, he'll charge you $15 for one and have you believe it's a special component.... yeah right.....)
Wire the diode in line with the idiot wire on your alternator to stop the I output of the alternator backfeeding keeping the coil running. (the line on the diode should be on the load side of your wiring)

HTH
Drew

 

[kingswood country]

So what would I be asking for when I go get a relay? Just a Holden style relay or something more specific? And what size fuse would you recommend? I'll have to have a relay infront of me to understand a bit better, though a diagram would be awesome if anyone had one

 

[drewVHSS]

You usually can't go wrong with a narva 30 or 40 amp relay.
If it doesn't work the first time, swap 85 with 86.
The diagram is on the side of the relay with the numbers matching up to the pins.
Diagrams are on the net somewhere, although i googled earlier and couldn't find the easy to read diagram for you, only schematic style ones that I have a little trouble understanding!
PM me when you've bought one and i'll guide u through it.
Dont be suprised if you need that diode though.

 

[kingswood country]

I'll get one anyway, that way o can't go wrong, thanks for your help, I'll try and look and ask around for a diagram in the meantime.

 

[ari666]

lol, i was way off with my numbers

thanks google:

its really easy. one side is a magnet and the other side is the switch. when you power the magnet (old wire from the coil and earth) it closes the switch and creates a path from the battery to the coil.

doesnt get any simpler than that

 

[the_boozer]

as its hj after youve added the rely does your hand brake light work if not you'll need to add a diode on the alternator charge light to stop the rely latching. (staying on) personally i tend to replace the resistance wire and not worry about the relay but have done the relay before , if you find the relay is latching worry about the diode then usually the current the handbrake light draws is enough to make the relay open