Rembrant's new non-Bullnose project

[FuzzFace2]

I am with Gary on the #10 wire for the starter trigger wire.

I run a McRobb PMGR starter, made in the USA, on my drag car and they also say use #10 wire and is wired like shown.
It was done almost 15 years ago now.
Dave ----

[ArdWrknTrk]

Rembrant wrote

......
Oh, and what size wire do I need for the trigger wire to the PMGR starter? I seem to recall that it only draws 4amps?

IIRC it was 40A to pull and 13A to hold.
Gary does have the sheet here on the site.

I'm using a 40A cube relay and 12Ga. wire.
It's been working for as long as I've had my little relay box installed,

[Rembrant]

Gents,

I'll pulled the new DSII wiring harness out of the package today and it prompted me to check my new coil (again) to see if I could determine if it required an external ballast resistor or not. Ideally it is indicated on the outside of the coil, but it is not noted on mine. It's a Spectra Premium C610 coil from RockAuto:

https://www.rockauto.com/en/moreinfo.php?pk=6280596&cc=1121443&pt=7060&jsn=454

Screen snip below. I ordered the coil for a 1984 F150.



I was reading some different stuff online, like the nice write-up below, and my 1984 Factory Service manual to see if I could test the coil with my meter to determine with 100% certainty whether the external resistor was needed or not.

https://www.gomog.com/allmorgan/coiltest.htm

The 1984 Factory service manual gives the following specs to check the coil:

Primary winding ohms: 0.8 - 1.6
Secondary winding ohms: 7,700 - 10,500

When I check my new Spectra coil, it reads 9,600 ohms on the secondary, which is fine, but it reads 4.6 ohms on the primary.

With a reading of 4.6 ohms, it's way off of what the FSM says it should be (if it was the original 1984 Ford coil at least). It seems like it doesn't need the external resistor, but maybe I'm doing something wrong.

Any advice from the Duraspark II knowledge base?

I don't care if it needs the resistor or not, I just want to confirm it somehow. Thanks gents!

[Rembrant]

Second wiring question...

The brown wire in the diagram below (full 12v+ to coil during starting only). What is the point of having this wire on the "I" terminal of the solenoid? I know what the wire does obviously, but my Bullnose trucks never had a wire on the "I" terminal of the starter solenoid/relay.



The reason I ask is that I already have a starter solenoid/relay, but it's one of the ones that does not have the second "I" terminal. I guess the point of it being on the starter relay is that it gets full battery voltage and does not pass through the main harness into dash and fuse box, etc.

[Gary Lewis]

I see in the Spectra catalog that the C610 is the right coil for an '84 F150.  But the EVTM, shown below, says there's a 1.1 ohm resistor in the wiring, so I would expect you to need a ballast resistor.

As for you finding 4.6 ohms on the primary vs the spec of 0.8 - 1.6 ohms, have you checked to see if your DVM shows 0 when you put the leads together?  Low resistances are hard to measure and the leads sometimes cause the readings to be off a few ohms.

[Gary Lewis]

That wiring diagram is for a simple ignition switch, meaning one that doesn't have the different circuit for Start which bypasses the ballast resistor like the Bullnose trucks have.  So they use the I terminal, which gets full battery voltage when the relay when it is energized.  That effectively bypasses the ballast resistor.

[Rembrant]

Gary Lewis wrote

As for you finding 4.6 ohms on the primary vs the spec of 0.8 - 1.6 ohms, have you checked to see if your DVM shows 0 when you put the leads together?  Low resistances are hard to measure and the leads sometimes cause the readings to be off a few ohms.

Gary, yes sir, I always check and it does read zero with the probes touching.

At the end of the day, it's not a big deal and I'll test it with power on it when I have it all wired up, it's just one of those things that annoys me greatly that it isn't indicated on the outside of the coil one way or another.

[Rembrant]

Gary Lewis wrote

That wiring diagram is for a simple ignition switch, meaning one that doesn't have the different circuit for Start which bypasses the ballast resistor like the Bullnose trucks have.  So they use the I terminal, which gets full battery voltage when the relay when it is energized.  That effectively bypasses the ballast resistor.

Right. I'm just using a basic dash mounted ignition switch. I'll grab another relay that has both terminals...they're not expensive anyway. Thanks Gary.

[Gary Lewis]

I thought you might be.  

[ArdWrknTrk]

This kit is for vehicles being retrofit to DS-II.
Vehicles that had points didn't have the 'hot in start' wire that bypasses the resistance wire found in all our trucks.

The Painless diagram could just join the white (advance) and brown (full current to coil) wire together at 'I', but the key switched bl/r wire isn't going to provide enough current to reliably charge the coil.

As for your coil, it's obviously setup to only work with the DSII horseshoe connector.
There are two functions of the resistor. Minimize overheating of the coil because of all the dwell inherent in DSII and reduce load on the switching transistor in the module.

[Gary Lewis]

You could test the current flow to the coil.  At 12.8 volts it should pull 2.8 amps if it has a 4.6 ohm primary.

Similarly, a .8 ohm coil and 1.1 ohm resistor should pull 6.7 amps, and if the coil was to the other extreme of 1.6 ohms it should pull 4.7 amps with the 1.1 ohm ballast resistor.

But w/o the ballast the stock coil would pull from 12 to 16 amps, and Ford obviously realized that much current was too much for the DS-II module.

So if your coil pulls 5 - 7 amps on a 12.8 volt battery then you don't need a ballast resistor.

[Rembrant]

Gary Lewis wrote

I thought you might be.  

Oh...while I have you Gary...

Any suggestions on how to get run-only power to my carburetor choke? I know this has been discussed before, but I'm not remembering how to do this.

I am using a little fuel pump controller, so I guess I could use the fuel pump output to trigger a relay for the choke power.

https://www.revolutionelectronics.com/Products/Fuel_Pump.html

The little Holley pump says it needs to be fused with a 3-5 amp fuse, so it obviously doesn't draw much. The pump controller is rated for 7.5amp...or at least it has a 7.5 circuit breaker.

[ArdWrknTrk]

Not only too much current for the dinky trigger wire, but so much current it's likely going to cause arcing of the NSS or clutch safety contacts over time.

[ArdWrknTrk]

You could tap the alternator stator (bk/wh) wire or implement an oil pressure switch to trigger a relay like Bill Vose did.

[Rembrant]

Ya, I'm going to buy a new starter relay with both the "S" and "I" terminals to take care of that, and I'll install the ballast resistor and go with it for now. I'll do some tests once I have the 12v supply all hooked up.

I'll assume it needs the resistor for now. Thanks guys.

[Rembrant]

ArdWrknTrk wrote

You could tap the alternator stator (bk/wh) wire or implement an oil pressure switch to trigger a relay like Bill Vose did.

I installed a 3G from a 1996 F150, and everything else is from scratch basically, or with Painless wiring harnesses. I think I'll use the fuel pump output to trigger a relay for the choke. The fuel pump controller relay closes for 3 secs on power up, but won't stay closed until it gets a running tach signal.

[Gary Lewis]

Sounds like you have things lined out.  

[ArdWrknTrk]

Yep, I see that it works almost exactly like EEC fuel pump controls.
Should be fine since a typical 'Bosch' relay is only using milliamps to pull closed.

Edit: just saying how it has been done in other Bullnose trucks.

[Rembrant]

Gary Lewis wrote

Sounds like you have things lined out.  

I do...I think! One more question then...

What would happen if I installed this coil with 4.6 ohm primary into a Bullnose truck with a 1ohm resistor in the coil wiring? (PS: I just check the resistor that came with the Painless wiring kit, and it is reading 0.8 ohms).

I guess what I'm trying to say is, if I install the resistor, and it technically isn't even needed, will there be a negative effect on the ignition?

Can you think of a reason why an aftermarket coil would have such a high primary resistance? Would there be a reason for them to engineer it that way?, assuming the system it's being install in, like a Bullnose, doesn't require it.

[Rembrant]

ArdWrknTrk wrote

Yep, I see that it works almost exactly like EEC fuel pump controls.
Should be fine since a typical 'Bosch' relay is only using milliamps to pull closed.

Edit: just saying how it has been done in other Bullnose trucks.

I'm going to do just that Jim, thanks! I bought the controller to protect the pump (and for other safety reasons), but it will serve as a fine trigger for a choke relay. Any idea how many amps or milliamps a typical Holley choke pulls?