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Twisted6
Total Likes: 1
Original Post (Thread Starter)
#101389 09/24/2024 12:55 AM
by BobK
BobK
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.
Liked Replies
by BobK
BobK
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.
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