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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 573 |
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flame thrower coil is 4 years old.Is the rest of the ignition system stock, or has it been upgraded to some aftermarket electronic ignition? If so, which one. If Pertronix, is it the basic Ignitor, or the Ignitor II / III?
The basic Ignitor doesn't have a thermal overload protection. When it over-heats, it dies, and stays dead. Replace it. Since your engine started running again, that doesn't sound like the basic Ignitor.
The Ignitor II & III both have thermal overload protection. When they over-heat, they shut down. But once they cool back down below the threshold temp, they start working again.
Hotter than stock coils are not appropriate for breaker points. For points, coils should be restricted to 24k volts or less. Hot coils can draw enough current to burn the points.
Hotter coils draw more current, which causes the points/ ignition amp to run hotter. If over-heating seems to be a problem with the Flamethrower coil, try installing a lower voltage output coil... one with a higher internal resistance, Re (R sub e).
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Carry a bottle of water with you. Next time the engine dies in that way, try slowly pouring the water over the carbs, cooling them down. If that solves the problem, then the carbs may be percolating in the heat.
That's easier said than done with the 907, since the distributor and starter are directly under the carbs. The point is to McGyver some way of cooling the carbs and see if that gets the engine running again (ie, cures the 'percolation').
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80F isn't exactly "hot", but the engine bay temps can be much hotter. What temperature thermostat is installed? A cooler T-stat rating is better during the hot Summer months. Thermostats are available in 165ºF, 185ºF, 192ºF & 195ºF.
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The stock water pump's impeller is pretty lame, and doesn't move much coolant. It's also prone to cavitation at higher rpm, which leads to overheating.
The impeller from the Turbo 910 is a dramatic improvement and moves a lot more coolant. The 910 impeller's nose is longer, so it won't fit into the JH pump's housing. Take it and the original impeller to a machine shop, and ask them to shorten the long nose to match the original impeller's. After that, the rest of the rebuild is by the book, and cooling is greatly improved.
Of course, make certain the radiator core is clean and working efficiently.
I'm just clutching at straws, and not presenting any of this as the 'fix' you seek. Just some things to try.
Regards,
Tim Engel