Big block Ignition harness

[Brenton M.]

On my new ignition harness there is a black & pink wire with a black connector on it that i think connects to the plus side of the coil, But there is also a black wire with the same type of connector on it,i dont know where it goes.

My other question is, on the main harness i know that the windshield wiper motor harness in the ignition wire goes threw the fire wall, the black in pink wire goes to one side of the resistor, could some one tell me where the wire comes from that goes from the other side of the resistor to the coil, in to the R side of the sol.switch.

THANKS.

[Wayne M.]

Re: Big block Ignition harness

Brenton -- could you tell us what year of BB; there are small but important variations in some years. I assume your mention of firewall ballast resistor means we're not dealing with transistor ignition.

[Brenton M.]

Re: 1965 Big block Ignition harness

I'm sorry its a 1965 big block non TI ignition wiring harness.

[Jack H.]

Re: 1965 Big block Ignition harness

I'm sorry too. Why? TI was a mandatory companion option for L78 BB's in 1965...

[Rich P.]

Re: Big block Ignition harness

Is this a new harness you need to modify for TI?

Rich

[Chris H.]

Re: Big block Ignition harness

For the L78, replacing the TI harness is quite simple. As you disconnect the old connections, just plug in the new ones. I got a harness from M&H Electric and it was of high quality. Sounds you've got a non-TI system in there.

[Brenton M.]

Re: Big block Ignition harness

Thanks for your comments Rich, My car does not have the TI ignition it has been replaced with a regular big block ignition system.

[Michael G.]

Re: Big block Ignition harness

Brenton,

FWIW....small block engines could be had with TI as well. If I'm not mistaken would appear as they would on a big block engine. Meaning, not a great deal of difference. If your car is an original 396 could have been converted over to a standard ignition system w/o much fanfare. Not that difficult to change back.

[Wayne M.]

Re: Big block Ignition harness

Brenton -- If I understand correctly, you have an original '65 L78 car that has had the transistor ignition system removed and is now running on a contact points distributor. [welcome to the club ] Was it running before ? You have purchased a new engine harness (goes from the inboard firewall connection to the volt regulator, horn relay and horns, and alternator, on the driver side, and to the blower motor and starter on the passenger side). Can you tell us from whom you bought this and the part # ?

Your 2nd paragraph in post #1; Yes, the black/w pink stripe ignition wire (B/P) comes through the firewall grommet along with the 5 wires for the wiper motor and windshield washer, and goes to one side of the firewall ceramic resistor (on non-TI cars). The other side of the resistor has a B/P wire that goes to the +ve side of the coil. There's a second B/P wire that goes under the same coil connection, and it comes from the 'R' terminal of the starter solenoid (so that coil sees full voltage when starter is cranking).

Of course much of the above changes when the (T.I.) impulse amplifier harness is added into the system. All depends on how much of the original TI configuration has been modified; eg. the factory cut off a section of the 2nd B/P wire because there was no firewall resistor. Several wire connection types were replaced to allow connection to the TI distributor and amplifier harness. Would help to know how much of this remains.

[Brenton M.]

Re: Big block Ignition harness

Thanks Wayne you have been very helpful that's what i needed to know, there is none of the TI System remaining. what i have is a 1965 engine harness for non TI ignition. the engine harness has the voltage reg. connection the alt. connection the horn relay connection all on the drivers side of car. it also have the starter wires, heater blower on passenger side of car, But what I'm not sure about is, there is a B/P wire and a Black wire with a female connection on them that reaches midway of firewall, where do these wires connect.

[John H.]

Re: Big block Ignition harness

Thanks Wayne you have been very helpful that's what i needed to know, there is none of the TI System remaining. what i have is a 1965 engine harness for non TI ignition. the engine harness has the voltage reg. connection the alt. connection the horn relay connection all on the drivers side of car. it also have the starter wires, heater blower on passenger side of car, But what I'm not sure about is, there is a B/P wire and a Black wire with a female connection on them that reaches midway of firewall, where do these wires connect.

Brenton -

If that's a Lectric Limited (or M&H) engine harness, you might call them to dope it out.

[Wayne M.]

Re: Big block Ignition harness

.....If that's a Lectric Limited (or M&H) engine harness, you might call them to dope it out.

John H. has good advice. You say your engine harness is new, yet the above two sources are the only ones that manufacture reproduction. And they definitely do not make a 396 engine harness that is NOT for transistor ignition; although you could make a few temporary connections to allow use of a contact points distributor, without the need for the additional transistor ignition harness and amplifier. I'm thinking that this is where you're at.

Below is a Photobucket pic of a partial original early 396 engine harness (RH side of pic to lower middle) and a partial TI harness (upper left of pic to lower middle) from the same car. To the left of the plugs with the purple wire, you can see a green wire with insulation (to the temp sender on the manifold); a black wire with pink stripe (from the starter solenoid 'R' terminal -- this would go to +ve terminal of ignition coil if you had no transistor ignition) and a black wire (ground from bolt on starter mount to blower motor ground and on to wiper motor ground). This photo might help visualization.

The other black wire w/pink stripe comes from the "IGN" terminal of the ignition switch, thru the firewall grommet, to one side of the ballast resistor; the other side (also) goes to the +ve side of the coil (but this section of wire is cut off on factory TI harnesses).

[Brenton M.]

Re: Big block Ignition harness

Hello john, thanks for that information, Look like the harness i have purchased is a 1965 corvette big block TI ignition harness, can you tell me what i need to do to get this harness to work with my big block non TI ignition system.

THANKS

[John H.]

Re: Big block Ignition harness

Hello john, thanks for that information, Look like the harness i have purchased is a 1965 corvette big block TI ignition harness, can you tell me what i need to do to get this harness to work with my big block non TI ignition system.

THANKS

I'm not familiar with the configuration of the BB T.I. ignition harness, but here's what you need to make the points system work:

1. 18-ga. black/pink wire from the "IGN" terminal on the ignition switch, through the firewall grommet, to the bottom terminal on the ballast resistor (switched 12V feed to the resistor).

2. 18-ga. black/pink wire from the top terminal on the ballast resistor, through the harness, to the (+) terminal on the coil (switched current-reduced feed from the resistor to the coil).

3. 18-ga. black/pink wire from the small "R" terminal on the starter solenoid to the (+) terminal on the coil (full 12V feed to the coil (+) only when cranking).

4. Black primary wire from the distributor base to the (-) terminal on the coil (points open/close circuit).

If you have those elements present, it'll run.

[Brenton M.]

Re: Big block Ignition harness

Thanks John. That took care of the problem.