Fresh motor won't start

[Jerry M.]

Installed rebuilt 340 hp in my '62 chassis to test fire before body drop. I hooked up the wiring per the attached diagram from RJM. On first try at starting, motor tried to start right away but then almost immediately died. Since then it will crank over but not even try to start.

I took some readings which are penciled in on the attached drawing. Note that across the ballast resister I'm only getting 5.3v at the discharge (?) of the resister and at the positive terminal of the coil. I'm hearing that this should be around 9.0v. It reads 12.2v until points close (?) which then drops to 5.3v.

I'm wondering if this is not sufficient for a proper spark. Pulled a couple of plugs which were a little wet and I may have flooded it while trying to get it to start yesterday. Getting a fairly bright white spark at test. Thinking that it might be a resister problem, I have replaced it now three times (one CC repro (tested at 2.1 ohm), one nice looking original off ebay (tested at 1.8 ohm), and one very ugly one that was on the car when purchased over 40 years ago. Same result (5.3 volts out) with all three.

Maybe a coil problem? Supposed NOS 081 bought off ebay years ago. I don't have a replacement at hand to try.

Appreciate any help.

Jerry M

62 wiring dia.jpg

[Patrick B.]

Re: Fresh motor won't start

Does the battery go down to 5.3v when the starter is cranking? If so the battery is probably the problem. If not, the solenoid would be the suspect if the voltage at the R terminal is not the same as the battery voltage.

[Timothy B.]

Re: Fresh motor won't start

If the spark plugs are clean jump a 12 v wire to the coil + and see if it starts.

[Mark E.]

Re: Fresh motor won't start

With the engine off and ignition on, there should be about 8v at the output of the ballast and at the coil's + terminal.

While the engine is cranking, there should be full battery voltage at the coil's + terminal.

Another thing to check are points, condenser, and their connection to the coil including the ground wire below the breaker plate. A poor primary circuit or condenser will cause a hard start/no start. Make sure the wire from the coil's - terminal to the points is in good condition with tight connections. The easiest way to test the points and condenser is to replace them with a known good set.

[Jerry M.]

Re: Fresh motor won't start

Thanks for the input guys. That gives me a few things to check when I get back in town.

BTW, battery is brand new; distributer was just checked out by very reputable, NCRS known specialist with I believe new condenser and points; starter and solenoid are fresh professionally rebuilt. As mentioned previously, three separate ballast resistors have been installed.

I'm still learning about the ignition and starting electrical, so concerning Mark's comment, with the engine off and ignition on, I'm finding 12v at the output of the ballast resistor (indicating that the points are open ?) which drops to 5.3 when bumped (to when the points are closed ?). Is this how that works (in principal, not the low voltage reading).

[Jerry M.]

Re: Fresh motor won't start

Thinking more about this, could a bad condenser cause a low voltage (ie.5.3v) output from the ballast resistor?

[Jim L.]

Re: Fresh motor won't start

I'm finding 12v at the output of the ballast resistor (indicating that the points are open ?) which drops to 5.3 when bumped (to when the points are closed ?). Is this how that works (in principal, not the low voltage reading).

Thinking more about this, could a bad condenser cause a low voltage (ie.5.3v) output from the ballast resistor?

yes and no, in that order.

[Greg H.]

Re: Fresh motor won't start

Hi Jerry,
Simple test is to attach your loose spark plugs back into the plug wires and ground them on the engine and look for the spark at the gap when you attempt to fire the engine. If No spark I suspect your coil.

[David H.]

Re: Fresh motor won't start

Jerry

By any chance, has your ignition been left on for an extended period WITHOUT your engine running?

Dave

[Jerry M.]

Re: Fresh motor won't start

Dave
Ignition "on" at this point is by a simple toggle switch. It may have been left on for maybe a minute or so (maybe longer ???) while I was checking things out and taking some voltage readings, etc. What effect would this have?
Thanks
Jerry

[Paul D.]

Re: Fresh motor won't start

If ignition is on for a extended period of time and the points are closed or close enough to arc, you would have burned up points.
I may have missed something, so please excuse my back tracking. You are test firing this engine using a improvised harness, correct? If so, do you have a wire running from the R terminal on the solenoid to either the coil or the side of your resister that connects to the coil? This wire would essentially by pass the resister and allow full battery voltage to the coil during cranking and then go cold after the starter disengages and you would then have reduced voltage at the coil (and points) after the engine is running. This is what Patrick was asking in a earlier post.

[Jerry M.]

Re: Fresh motor won't start

Okay, I'm following this thought now. That may have been a possibility, and I understand now how that could have burned up the points, and caused a no start condition. I'll check point condition when I get back home this weekend.

I'm still unsure why I'm only getting 5.3v at the ballast resister output. Could this be a result of the burned points as well?

I really appreciate all of the help and suggestions.

[Paul D.]

Re: Fresh motor won't start

You would only have voltage greater than resister voltage (5.3) while the starter is engaged. Inside the solenoid is a large washer that, when the starter is operating (spinning), it bridges the positive battery cable and the "R" terminal causing the "R" terminal to have full battery voltage while the starter is engaged. During cranking, with a healthy battery, you should get 10-12 volts on this terminal. A wire run from this terminal to your ballast resister output would provide this greater voltage to the coil during cranking to aid starting.