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Old 04-12-2013, 05:56 AM   #1
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Displacement gasser

Folks that find a gasser , usually a plaining boat that will be run as a displacement boat need to make a check.

Depending on the age of the boat the ignition system may need a change.

AS the engine probably was set to run 3000-3500RPM for long periods of time , the spark plug heat range was selected for that service.

HOTTER spark plugs will be required to run basically just above idle , however there is a danger if these plugs are in when charging at 3500 again of the plugs causing pre ignition.

Simple cure is platinum plugs that have a wide heat range..

Or simply HOT up the std ignition to fire the std cool running plugs.

Take a look at a plug after the first 10 hours of displacement cruising to see what is happening.

Another tip is to take a look at how the secondaries on a 4bbl carb open.

The hot rod folks have a variety of systems to change the opening method.
A swop to mechanical is fairly easy and if set right will allow one to run on the smaller primaries longer in the RPM range.

The de-fuling secondaries are still operable , just tales a longer or harder push on the throttle.

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Old 04-12-2013, 07:06 AM   #2
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There is a ignition box made by MSD that can fire 3 sparks per power stroke under 3k rpm, That should help clean up the low rpm operation wile using the stock spark plug heat range../ Craig S
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