Intermittent slow crank when coil wire is plugged in to the dist

[ESP47]

This is a 68 Barracuda with 408 blueprint engine stroker with their Ready to Run distributor that comes with an internal ignition. No ballast. I rewired a good amount under the hood and dash and swapped out the bulkhead connectors not too long ago. I'm just now attempting to start the engine for the first time.

Symptom is the starter slow cranks about 4 out of 5 tries with the turn of the key. If I use a remote starter on the starter relay or I unplug the coil wire from the distributor, it'll crank just fine.

I did identify one problem, which is I'm only getting 10v at the starter relay on the "run" wire when I have the coil wire unplugged and the engine is cranking normally. When I plug the coil wire back in, I see 7-8v or so.

Anything else I should look for on top of ensuring all my connections and continuity look good? I'm not understanding exactly why I'm getting less voltage at the starter relay connector when I have the coil wire plugged in vs. when I don't.

I have gotten the engine to start a few times and got the timing dialed in close enough to at least have it idle on it's own but this problem is puzzling me.

 

[Dana67Dart]

When you say coil wire do you mean the high voltage spark plug wire or the 12v feed to the coil?

 

[Bewy]

Using a lot of initial timing is the usual cause. Removing the ign, removes the load, & so the engine cranks faster
Fixes:
- check all starter connections
- use heavier starter cables
- get a starter that produces 3+ hp [ MSD dyna force ]
- use a switch to disable ign while cranking, then switch in ign once engine is cranking

 

[eekvonzipper]

- use a switch to disable ign while cranking, then switch in ign once engine is cranking

^^^ RaceCar Stuff! My Dad used to start his 440 this way... Needed a bunch of Timing for some reason.
He would start it rolling and then let Me flip the Switch and Bam! She would light right off!
Thanks Bewy for that Memory!

 

[Dave999]

check earth strap from motor to chassis/mount back plate. i.e make sure the chassis end is bolted on on the chassis side of the rubber insulator
check the battery + connector. if its a clamp to wire fitment, rather then a soldered and crimped original check its all good under the clamp
set initial timing to 10 BTDC and see if it starts ok

you have a current flow issue rather than a voltage issue by the sound of things.....

you symptom is identical to what i had when i had failed to connect up the earth strap after an engine out job

voltages all look good
current however isn't because in my case we are accidentally expecting the starter motor to find a route back to the battery through the coolant and radiator and the throttle cable as it passes through the fire wall ferrule.

you have found by taking the ignition load off the system, which will also be earthing via the same restricted route, that it spins a bit faster.... i.e you took an extra 3-7 amps out of the equation and the starter had more to work with.

Its a guess not everyone is as clumsy/forgetful as me..... i only noticed because it was dragging on the ground... and this is of course the first time i'm admitting this in public

Dave

 

[Oldmanmopar]

MSD digital 6 has a built in timing retard for this reason. The unit retards the timing 20 degrees while cranking. . As soon as it starts and reaches 800 RPM's it advances it 20 degrees. You can also do this with weights and springs if you know what you are doing . Weld up the slots from 1/2 to 3/8 outside and use one light spring to hold the advance until it starts. 1/2 -3/8 is 20 degrees . The light spring will hold the timng back until it fires up.

The kill switch mentioned above is the easiest fix. switch on after you have it cranking.

 

[AJ/FormS]

If you are running so much Idle-advance as to affect the cranking, my guess is that the Transfer slots are gonna be nearly closed too, just so it will idle slow enough. That's also gonna lead to long crank times as the engine struggles to get fuel, and whatever it does get, if it ain't burning it, some to a bunch of it, is gonna wash the oil off your cylinder walls, and end up in the oilpan.
Do your engine a favor; dial the Idle timing back, get the transfers set right, then fix the Timing Curve.
That's my 2cents