Technical HEI wiring into '57 Chevy question

I'm super lost when it comes to wiring but thanks to the HAMB I've got my new alternator wiring figured out but I have a question about conflicting info I've gotten about wiring in a big cap Chevy HEI into the car.

I understand that the ballast resistor needs to get eliminated and that the factory wiring for the coil is too small to handle the HEI, but I want to know the best way to do it.

One source said "Remove the 3 wires that go from the ignition switch to the ballest resistor and coil. Connect a jumper between ign1 and ign2 and run a 14 gauge wire from the jumper to the HEI "bat" terminal."

This was referring to a '56 Chevy, I have a '57, not sure if the ignition switches/wiring is different.

The other source said "On a '57, you only have one "IGN" terminal on the switch with a 20 gauge tan wire. Run a larger wire from the "IGN" terminal to the "R" terminal of the starter and from there run a larger gauge wire to the + coil terminal. This will eliminate the resistor and provide 12 volts from the starter while cranking"

So my question is, can anyone confirm that the '57 Chevy does not need a jumper wire on the ignition switch, and assuming it does not, is it best to run a wire down to the starter and then back up to the coil, or can I just disconnect the brown wire going to the ballast resistor and replace it with a bigger wire that goes directly to the coil?

It seems odd to run the coil wire down to the starter and back up to the coil.

I also read someone said to run the wire from an IGN post on the fuse box to the coil, instead of from the ignition switch. Any good reasoning for that?

 

If it was mine I would run a 12 gauge wire to the HEI.





Bones

 

If the 57 does indeed only have one IGN terminal on the switch, then you just connect that terminal to the HEI BAT connector. There is no need at all to connect anything to the R terminal on the starter with an HEI, if the ignition switch provides IGN power in both the cranking and run positions.

I forget how the switches work...and not sure I have 57 specific info around here, anyways.

 

You can't beat a relay if higher current is required.
Use the existing small gauge ignition wire (bypass the ballast) to signal the relay only and then find a good high current fused source and use heavier cables to connect the relay and HEI.
Good luck.

 

My 57 ignition switch does not power the coil [via ballast] while the ignition switch is in "start position". Release the key to "run position" and there is power to the coil.

On a 57 Chevy you need to splice together the Ignition wire and the "R" wire from the starter [ both should be green wires] then to the battery terminal on the HEI.

If the Engine doesn't have an "R" terminal on the starter [or R wire] , Tee off the "S" wire [purple] instead . BUT add a diode inline so the ignition doesn't keep the starter engaged.

 

Just as a security feature you could just run a 12 gauge wire from a 12 volt source to a H.D. toggle switch under the dash and turn it on when you start it up then turn it off when you turn the key off.

 

I'd keep the points distributor.. That car has one of those iron units too, they were so well built..

 

A GM HEI will require a ball peen modification to the firewall or side engine mounts that move the engine forward 3/4 of an inch.

Buy a "stock cap" conversion. Mine is powered by a wire from the fuse panel (aftermarket) that is an ignition circuit.

 

For clarification, this '57 Chevy was originally a 6 cylinder and sat with no engine in it for about 15 years. Then a newer small block engine was swapped in but the swap was kinda rushed and cobbled and I'm trying to go over the install and do things right.

I believe it is a "big cap" HEI but I could be wrong, it fits with some clearance to the firewall which was not modified (do the 6 cyl cars have a deeper indent on the firewall?) I'm really only using this distributor since it was there. My preference would be an earlier engine altogether, this is all done for budgetary reasons.

 

This sounds similar to the other info I found about 57's and that would confirm that the '57 is different and explains why it was suggested the wiring needs to go to the starter first and then to the distributor. I will try to get pictures of the back of my ignition switch and starter to confirm this but this sounds right. Would be a nightmare of confusion to wire it up and have no coil power at the starter, exactly the kind of issue I'm trying to avoid.

Thanks for this response, and all the responses. I'm a real novice at this particular issue so the feedback means a lot to me.

 

I scanned quickly.
It may have already been mentioned...
The "wire to thr starter, then back up again" is the solenoid contact that shoots a full 12v to the coil while cranking, then goes dead again when you stop cranking, which lets the OTHER ign wire from the switch take over with its "resistor voltage" for running after the engine starts.
Many cars switch back and forth as you do your start and run routine. That is why you have to put both wires together plus jumper across the resistor or remove it completely- so you have 12v ign while cranking, plus still 12v when running. You need both.
I like the reliability of a good heavy duty switch.
I have used relays before, but be aware that relays can fail eventually. Pick your choice, and carry a spare just in case.
I used to use relays for high power items until one late night my headlights went out completely. Always have a trusty fallback position!



WHY BE ORDINARY ?

 

That explains why they're asking for a jumper from the switch, to the starter, and then back to the coil, which makes sense and I appreciate it, but now I'm confused on exactly what I'm hooking up and to where. Is there a crank-only position on the ignition switch that I'm running a wire from, to the starter and then to the coil, and a run position that I need to run from the switch to the coil directly? If both wires end up at the + side of the coil, won't that back-feed power into the starter?

I apologize for being so needy, but I really need this stuff explained like I'm 10 years old so I can make it work and figure out why exactly I'm doing what I'm doing. I very much appreciate the advice I've gotten so far.

 

From IGN on keyswitch go straight to HEI power, with no resistor. (if you follow advice to use a relay, it goes to turn this wire on and off)
That takes care of the RUNNING power.
Now you need to assure 12v to the coil while cranking the starter...
It is usually the small terminal on the start solenoid that should also have some sort of IGN labeled on it too.
I am used to Ford style solenoids, so I cant be sure how GM labels theirs, but I think it should be the small wire IGN on the starter solenoid too.
One from the IGN on keyswitch gives running 12v to the coil while the solenoid IGN gives 12v to coil while cranking.
When Start vs Run switches back and forth, you will get 12v from either source.
The two small terminals on your starter should be one small wire that "Clicks" the solenoid (from Start switch), which leaves the OTHER small terminal (ign?) remaining as the 12v Out as the coil 12v source to your new hei coil..
I hope I said it right

Oh.. and Yes, there is a Start terminal on the keyswitch that should be labeled ST or similar, that sends power to the small terminal to click the solenoid. If you try to take your "cranking 12v" from there at the keyswitch, (input to the solenoid) instead of the "other" small wire output terminal at the solenoid, you risk feeding power to it when you want it off. So you need one wire from IGN at the key to coil , and one 12v output wire from IGN term at the solenoid, both going to coil.
That way they will take turns keeping the coil powered without having a feedback loop that keeps things ON when you want to turn everything off.
I hope that makes sense.

WHY BE ORDINARY ?

 

Yes there is a crank only position. Single terminal below ACC.

 

Thanks.
They might not all use the same labeling letters, but the markings and clues are usually pretty easy to decipher .
Pictures are always great


WHY BE ORDINARY ?

 

That really makes a ton more sense. I appreciate the followup. I'm making the assumption the ignition switch can handle the extra power from the extra gauge wire due to the other sources I had never mentioned turning it into a relay circuit, hopefully that is correct.

Beyond that, it seems fairly simple now that it's been explained to me, and I DEFINITELY would have done it wrong if I hadn't asked here, so thank you for the detailed writeup.

 

There are two different ignition switches used by Chevy in the mid-late 50s. the early one has IGN1 and IGN2, and one of them is only on during Run, the other is on only during Crank. This switch needs the two IGN terminals both connected to the HEI, so it gets power while cranking, and while running.

The later switch has only one IGN terminal, like Johnny pictured. This type of switch only needs one wire from that IGN terminal to the HEI.

I just don't remember what switch a 57 car used.

 

^^^^^ I've once worked on a truck and nothing to due with electrical. Didn't the trucks continue using 55 -56 car ignition switches into 1959?

 

I think so...the one I just put in my bread truck has two separate IGN terminals.

 

55 and 56 Chevys have ign 1 and ign 2 on the switch
57 Chevys dont. They rely on the "R" post on the starter.
Where the harness goes through the grommet by the ballast on the firewall there is 2 green wires
One comes from the ignition switch to the ballast
The other comes from the starter to the "coil side" of the ballast.
Splice these 2 together to feed the HEI
And remove the Ballast

If you want to keep the ballast (for appearance) simply bridge the ballast and hook it up to the HEI ( bridging also splices the 2 wires together)

 

The HEI requires 12V if you just do away with the resister it will work. Use the one to the resister and the one from the solenoid together between the two it will have power when needed.

 

There's a reason why GM stepped up the gauge (down numerically) on wire size so why all this talk about rerouting existing wiring?

 

We never got to see the distributor. Is it actually a GM hei?

Phil

 

From second sentence in OP's question. " big cap Chevy HEI"