TLDR: Is it normal for water to sizzle when splashed on the plugs if it doesn't sizzle on the head itself?
I got my grandfather's 1954 QD running again but had problems with it overheating at wide open throttle. I discovered the water pump grommet was split and figured that was the cause of overheating.
After rebuilding the water pump I got a lot more water and much warmer water out the exhaust bypass. But I also still got a sizzle when splashing water on the heads after a couple minutes at WOT.
I looked in the service manual for possible causes. It listed blocked water passages, running too lean, and carbon buildup.
The carburetor seemed adjusted correctly and I wanted to save pulling a 60 year old head for last, so I ran the SeaFoam de-carb procedure at 3/4 throttle (because full throttle apparently leads to overheating).
Afterwards I ran a couple minutes at WOT, then stopped and splashed water on the heads. Sizzle. But I also noticed water beading in the corners of the head cover.
Another run and more careful splashing showed that the sizzle is coming from the plugs, not from the head.
So... my stupid question. Is it normal for the plugs to sizzle when water is splashed on them if the head itself will bead water? I still can't touch the head for more than a partial second. Certainly not for a slow three count. But my engine no longer boils water splashed on it. Good enough? Plugs are J6C and new after the de-carb.
I got my grandfather's 1954 QD running again but had problems with it overheating at wide open throttle. I discovered the water pump grommet was split and figured that was the cause of overheating.
After rebuilding the water pump I got a lot more water and much warmer water out the exhaust bypass. But I also still got a sizzle when splashing water on the heads after a couple minutes at WOT.
I looked in the service manual for possible causes. It listed blocked water passages, running too lean, and carbon buildup.
The carburetor seemed adjusted correctly and I wanted to save pulling a 60 year old head for last, so I ran the SeaFoam de-carb procedure at 3/4 throttle (because full throttle apparently leads to overheating).
Afterwards I ran a couple minutes at WOT, then stopped and splashed water on the heads. Sizzle. But I also noticed water beading in the corners of the head cover.
Another run and more careful splashing showed that the sizzle is coming from the plugs, not from the head.
So... my stupid question. Is it normal for the plugs to sizzle when water is splashed on them if the head itself will bead water? I still can't touch the head for more than a partial second. Certainly not for a slow three count. But my engine no longer boils water splashed on it. Good enough? Plugs are J6C and new after the de-carb.