Mopar LA small block 318 ignition problem

[Brian Clark]

Hello everyone,

I'm new to the forum and I am currently restoring a 1974 dodge dart swinger. I removed the engine a couple months ago to clean, rebuild. etc. The engine is currently installed and everything is hooked up the way it was before I removed the engine. The problem that Im having is that when I turn the key the engine fires, when I let go to the ignition, the engine dies. I already replaced the ignition switch in the column so that's no longer the issue. The ballast resistor isn't a problem due to that I have a msd 6A cal box installed. I'm stumped and really need some answers or at least a path for me to follow. Thanks for the help!

 

[67Dart273]

Did the MSD ever run right or did you just install it?

If it had been running you may have bumped some wiring up near the ballast. If you just installed it you may have it wired wrong

There are two feeds involving the ballast. One, IGN1 "run" is hot with the key ONLY in "run." It feeds to the one end of the ballast where (if a 4 pin) the two pins are jumpered. THIS GOES DEAD in "start"

During "start" the feed comes from the key and what I call the "bypass" circuit. Originally, this fed full battery power to the coil+ side of the ballast for a hot spark for starting. This is normally brown but not always.

On the opposite end of the ballast from the first described above, you have 1 wire terminal each. One originally fed back to the Mopar box and is now not used (MSD) The remaining one contains the bypass circuit, and it must be jumpered to the remaining wires on the other end.

You can buy male flag/ spade "push on" terminals, and one easy way is to simply make up a male to male jumper to replace the ballast

 

[67Dart273]

Also I don't know if you can PM me with only one post, you can try. I have a digital 74 shop manual, but it's "huge." You cannot email the file. If you want to PM me, mail me a USB stick with a return mailer, I'll copy the files and mail it back

 

[Professor Fate]

Also beware of the '74 only seatbelt interlock system... lots of posts on here about those.
It cuts out your ignition when triggered.

 

[67Dart273]

^^Small correction it (the interlock) cuts out the starter relay. And to the OP you should bypass it. Look on the driver's inner fender for a box about the size of a horn relay with a (used to be red) reset button out the top. There are two "yellowish" wires. Splice them permanently together

The interlock was a 74 year only deal mandated by the federales, and people raised so much hell that it was stopped.

 

[Bewy]

It sounds like you are getting power to the 6A in the crank position, but losing power in the run position. Check the ign switch, wiring etc.