hoping the brain trust on here can help me figure out my starting/cranking issue.
I'm putting my truck back together...1979 f150 4x4.
Swapped out the motor from a 351m to a 400 and the motor came w/ an HEI distributor.
I got rid of the coil, took the wires from the duraspark unit to get 12v on run/crank to run to the HEI.
Tried to get a first start last weekend w/ a friend and noticed a few odd things.

At first, noticed that the starter once hooked up would crank on run position. Didn't actually think much about this at the time.
We had to crank a bunch to get it fired up and battery ended up dying/struggling, so we hooked up to my friend's truck battery w/ jumper cables.
At this point, solenoid/starter would not engage at all, on either run or start.
We ended up using a remote started hoooked between the S terminal and the starter post to get it to crank.
At first, I thought the solenoid gave up the ghost. replaced it today w/ same no click/crank on either run or start.
I'm pretty sure I didn't switch my S and I post wires, as the original wires only fit on their respective posts. The pic above is the new solenoid, and I had to replace the I wire end w/ a ring terminal as the original push on terminal did not fit the new post.

My understanding is that the S post gets energized during start, allowing current to pass to the starter terminal and the I goes to the coil. I deadheaded the I wire since I wasn't needing a coil w my HEI.
I don't see any in-line fuses on any wiring diagram for the ignition system. There is a megafuse going to my alternator coming off the positive battery post of the solenoid.

Any ideas?

PS. we were able to get it to start, run, set initial timing, and run it at 2000rpm for a bit (not as long as I would have liked) and had to stop for a carb/fuel issue that I'm sorting out right now.

 

if you can short from the front lug to the S post and the starter engages, then the solenoid is fine. You need to check the wiring from the ignition switch, through the neutral start switch (assuming it is an automatic) all the way to the solenoid.

maybe the wiring harness for the neutral start switch got disconnected/loosened during the engine swap, etc...

 

shorting between the S and the rear post (starter post) gets the starter cranking w/ a remote starter switch.
I'll check the NSS

 

update.
replaced the NSS and the truck will crank now. not sure if I just needed to adjust the old switch so the small hole was lined up or if the switch itself went bad
the only thing is (and I noticed this before it stopped cranking) the starter wants to engage in run position and not just in the crank position.
did I wire the solenoid wrong? i don't think I did as the original posts only fit on their respective I and S posts. I can put a test light on those wires I suppose but not sure why it would want to crank on run unless the S wire is hot on run and not just crank.

 

Pull the wires off the S & I studs before testing for power.
You may want to pull the wire off the + side of the coil not to over heat the coil.

With a test light check each small wire for power.
The wire that has power with the key on gets put on the "I" stud of the solenoid.

Now with the test light on the other wire turn the key to start and see if you have power on it.
If so that goes on the "S" stud.
If all is right it should crank when key is turned to start and it should run.
Dave ----

 

took a look at the wiring diagram and figured out where I messed up.
My HEI needs 12v at crank and run, so I used the old wires going to the duraspark and spliced them together. The 12v run wire is feeding energy back into the 12v start wire, causing the engine to crank on run position.
someone on FB mentioned that one of those wires are 12v on run AND start, so I'll do some investigating w/ a test light and rewire the HEI.
If not, then I'm looking into putting in a relay into the system.

 

On the 80's trucks with DSII they say to use the W/B wire going to the + side of the coil as that should have power both crank & start.
I dont know if your wire color will be the same or not?

FYI you did not gain anything but lost money by changing out the DSII IGN for a GM HEI that you may not have room to turn the dist. as the vacuum can hits things.
Dave ----

 

I understood that the coil wire has an inline resistor that drops the voltage to 8-9v on run.

 

You can power a relay with the resistor wire and go to battery for full 12V. Doesn't solve the problem of a carburetor size HEI. Nothing is as easy as it seems.

 

OK for those searching in the future, the red wire after the connector for the duraspark is 12v on run and start. The white wire is only 12v on start. Got my electric issue sorted out. Swapped out the NSS and functioning normal again. Need to hook up linkages and vacuum lines to new carb and will try firing it up again soon.