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1956 30 hp johnson...Water in lower cylinder?? Head Gasket?

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cjbrill715

Regular Contributor
Hi guys, was running my 1956 30 hp Johnson (RD-18) In a 55 gallon drum today, and I pulled the plugs to see what color I was getting. The top plug was a nice golden brown with a little black, But the bottom plug was almost clean as a whistle. The compression reads around 120 psi top and bottom, but It does seem to have an issue idling down smoothly without cutting out. I can't find any exploded views of this motor, and I'm not too familiar with the anatomy of this motor. My question is, are these motors subject to water getting into cylinders if the head gaskets get bad?? It is running on both cylinders, but it seems a bit "tuggy/jerky" at lower rpms.
 
cjbrill715 said:
Hi guys, was running my 1956 30 hp Johnson (RD-18) In a 55 gallon drum today, and I pulled the plugs to see what color I was getting. The top plug was a nice golden brown with a little black, But the bottom plug was almost clean as a whistle. The compression reads around 120 psi top and bottom, but It does seem to have an issue idling down smoothly without cutting out. I can't find any exploded views of this motor, and I'm not too familiar with the anatomy of this motor. My question is, are these motors subject to water getting into cylinders if the head gaskets get bad?? It is running on both cylinders, but it seems a bit "tuggy/jerky" at lower rpms.
Click to expand...

Anyone?
 
racerone said:
Running on one cylinder ?---Does spark jump a gap of 5/16" on both leads, yes or no ?
Click to expand...

It is running on both cylinders for sure, I can tell by the sound. I just did the gap test, and the top cylinder jumped 5/16" with a snappy blue arc....However, the bottom cylinder (The one with the cleaner plug) didn't jump the gap....It gets spark on the plug, but evidently it's not as healthy as the top plug setup....I'm going to replace the plug boot, and possibly the wire on that one, and check the spacing between the coil and flywheel magnet. It's got new coils and condensors, the points are set at .02".....What else do you recommend??
 
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