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Old 05-07-2019, 05:40 PM
tmcdonagh tmcdonagh is offline
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Quote:
Originally Posted by Dave Neptune View Post
Tom, the plugs don't actually talk but they do leave clues to be read.

First, the lack of color on the electrode porcelain indicates a plug whose "heat range" is to hot as there is very little deposited, dark or light. A cooler plug will make more power, run smoother and allow deposits to coat the ceramic which is nothing more than a heat sink.

The darker color on the ground indicates a pour burn inside the cylinder. This poor burn most likely is the timing is to far advanced.

The color that shows is OK for "economy" however more power and cooler running engine needs a bit more color like Jerry mentioned.

Try a set of stock range plugs for a couple of hours and take another "read" of the color. You want to see the beige~tan on the porcelain and about the same on the ground albeit a bit darker. Set the gap to .030 with points and if you run an EI go to at least .035/. The additional gap will idle smoother and start faster too, a big advantage of the EI systems.

Do you know if the plugs shown are in the same heat range or did you go hotter for some "fix-it" reason?

When installing the plugs give the entire outside of the plug a thin coat of dielectric silicone. This aids in both rust prevention and heat transfer through the boots by maintaining "contact' for good heat transfer and the boots won't tear when removing.

NOTE the boots are a big part of the "heat sink" equation related to plug running temps.

Dave Neptune
Thanks Dave!. Oh, plugs don't talk! I thought they were not listening.

I replaced the plugs with Champion RJ12C's and gapped that @ 0.04 as suggested on the forum. I will go back and remove, regap at 0.03 as I don't have the electronic ignition yet and spray with the dielectric silicone. Are there better spark plug wires for heat dissipation?
The plugs were leftover by the previous owner and I have no knowledge of why they were installed.

After installing a new gas filter and plugs she still runs rough for 1-2 minutes, coughing, stumbling and backfiring. She settles down nicely after that time. If I restart her right away, it runs normally. If she sits for 4-6 hours or overnight, the histrionics return. I have not been able to pressure test her on the water as of yet.

Thanks again!
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