[Torx]

So i'm trying to backtrack the ignition on no spark.. and while i'm in the process of learning and exploring this points system.. I was wondering if the interlock safety system had anything to do with killing spark too alongside the starter kill.

I've already experienced the no starter turn over, but i've been bypassing that with a solo man remote switch wired to the starter.
Not sure if the bypass button under the hood is operable havent really messed with it much..

But while i'm giving this ignition points system a few more opportunities before throwing in the hei, I wanna make sure this seat system isnt screwing with me.
I got 12v at the + on the coil in ON position, tested various grounds with multimeter/battery after cleaning all ground points.. checked connectivity on the - wire going to the distributor points, and adjusted points in various ways and still see no spark or got nothing. Tested only the primary on the coil, but will the secondary, and mess with points again...

Just making sure i can rule out this pesky ignition interlock, but serves as a good "kill switch" feature too for would be theives, thanks

 

[ZumpTA]

I can't really speak on the no spark issue, but two questions come to mind. What's the condition of the condenser? and, What initial gap did you start from? I really just wanted to say that there's a step in-between what you have now and HEI. If you weren't aware, look into PerTronix Electronic Ignition conversion kits. They're only about $100 and completely do away with the points and condenser. If you're trying to retain the "stock" look but want more reliable ignition, conversion is the way to go.

 

[b_hill_86]

Don’t believe the interlock affects the spark. Could be wrong though.

 

[brianb]

The much maligned 1974 First Generation Seat Belt Starter Interlock System was mandated by NHTSA but only lasted one year. As we all know, it was improved and returned years later. I have this in my '74 car as well. I found it a fun and quirky vintage feature at first but soon it became annoying. I could not start my car until my wife first attached her seat belt followed by mine. If we didn't follow that exact sequence, no start. In my case I easily defeated it by disconnecting the electrical clips shown in this picture. I use the Pertronix Ignitor III system with no issues doing this. You can also see that I fuse protected mine in the 12 volt orange wire supply line for the Pertronix. You might be able to do this as well. Look for the 3 wire connector with Green/Yellow/Orange wires underneath your dash on the left side by the fuse box. FWIW I left in place the original 6 volt feed/resistor wire for the points style distributor. If I ever blow the fuse on my 12-volt Pertronix hook-up(which I've done) I can limp home and put in a new fuse if there isn't one in my glove box. My Pertonix runs fine on 6 volts unless I floor it whereby the spark dies off at 4000 RPM and the car takes a nose dive. For your viewing pleasure is a short film from 1974 explaining the 1974 system in the YouTube link below.

Seat Belt Starter Interlock System & Wiring Explained - 1974 GM, Ford & Chrysler - YouTube

 

[brianb]

As a follow-up to my post above: At the 2:50 mark in the film its explained that this system is tied into the starter circuit and not the ignition.

 

[Torx]

As a follow-up to my post above: At the 2:50 mark in the film its explained that this system is tied into the starter circuit and not the ignition.

Thanks for that bit of info, picture and the clip to inspect. Will check this out, and good to know it doesnt affect spark. So i can rule that out, but at the same time i probably want this hassle removed and disconnected lol. Thanks again, hahah and yes i saw that video i rolled my eyes a few times at how much of a hassle it looked to be back in the day.

 

[Torx]

On the subject of the interlock, im not sure how well it can live up today to being a theft deterrent quirky feature, but that would be the one and only reason i would keep it on..

 

[Injuneer]

I don‘t think it was intended as a theft deterrent. It was an attempt to increase the use of seat belts.

 

[brianb]

I appreciate the attempt for more safety but today the whole thing seemed like a "contraption." But that was the technology available back then.

 

[Injuneer]

I'm not trying to push it as a safety feature…. just trying to clarify for the OP why the NHTSA implemented the law.