Inliners International Forums General Discussion Engines Vertex magneto issue/question

Yesterday, my adult son and I started up my 1959 Chevy straight six ( 261 cubic inches) engine that had recently been rebuilt. Happily, it started on the first turn of the key after I spent a week re-installing the engine, trans, and other components. I spent some time tuning the idle and was happy with the outcome.

Today, I went to fire up the engine, but forgot to turn the fuel pump on. The engine ran for a few seconds until the fuel bowl was empty and then stopped suddenly. I then realized my error and turned the fuel pump on. The engine cranked but would not even cough to get started. I've spent all day chasing every angle of spark, air, fuel. Using a spark tester (wire between plug and wire that lights up with spark), I can see that there is spark but I've come to believe that the issue is with the magneto.

When I took the cap off to see what was going on, I saw that the engine builder neglected to put the red plastic isolator piece under the rotor, he probably lost it. I fashioned one from some gasket material and punched holes for the rotor, the conductor, and the two screw holes. Despite those efforts the engine still would not start.

I decided to ensure that the engine was getting adequate ground and using my multi-meter, I found that the engine was getting great ground, no issues. When I tested continuity from the frame to the Vertex (internal coil) magneto case, I saw that it was grounded, as I would have expected given that its mounted into the engine block, but I became concerned when I was getting continuity to the grounding terminal on the side of the magneto. In fact, I get continuity between the terminal and the magneto case too. I thought the grounding terminal was isolated from the case, so that when I used the switch on the dash it would ground out that terminal to stop the magneto.

Should the grounding terminal show continuity to the case?

Thanks in advance for any assistance.

Since the initial issue was fuel, did you prime it after running it dry?

Several times during the course of the day.

OK, Just checking the sample mistakes I make first. Is it a separate switch that grounds the mag to shut it off? Could the switch be bad and always grounding? Disconnect it? I haven't owned a mag on 60 years.

Yeah, I thought the same thing about the switch. I disconnected it and had a jumper setup to the frame in case the engine started. However, switch in circuit or not engine won't start. I still suspect that the mag is grounded full-time for some reason. I have a call into Joe Hunt magneto to inquire.

Perhaps. But I'm with Beater, the original issue was fuel starvation. Are you sure the system is primed and the float/seat is letting fuel into the bowl? Have you hit the engine with a shot of starting fluid? If it fires on ether the mix coming from the carb may be too lean for a spark to jump. Fouled circuit from running it dry - sucking gunk?

Plenty of fuel in bowl and pushed by fuel pump. Tried starter fluid several times, not even a cough hint of starting.

Talked to folks at Joe Hunt Magnetos today the P terminal (grounding terminal) should not have continuity to the mag body as its supposed to be isolated. I've removed the mag and will be sending to them for diagnostics and or repair.

It is good to have support from the maker. They will make short work if it and you'll have confidence is the repair. Let us know what happens and how long it takes.