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1989 Johnson 70 Spark Plug Type

puretic

puretic

Member
Hi, replacing my plugs as preventative maintenance. (J70TLCEM)

Marineengine states plug type is Champion QL77JC4.

Current plugs are NGK BR8HS. Haven't noticed any issues, ordered another set of the same.

Any thoughts as to the suitability of these plugs?

Cheers.
 
puretic said:
Hi, replacing my plugs as preventative maintenance. (J70TLCEM)

Marineengine states plug type is Champion QL77JC4.

Current plugs are NGK BR8HS. Haven't noticed any issues, ordered another set of the same.

Any thoughts as to the suitability of these plugs?

Cheers.
Click to expand...

The recommended plugs are inductively suppressed ........ Thats what the "Q" means

Your NGK BR8HS plugs are resistor suppressed ... that what the "R" means . They are also a cooler heat rating than the QL77JC4

Resistor plugs are generally not recommended for OMC engines and Champion "Q" type plugs are generally recommended for all VRO2 equipped engines.

If you must use NGK plugs use BZ7HS-10.
The "Z" indicates inductive suppression and they are hotter than your 8 heat rating. ( The -10 indicates that they are supplied gapped at 1.0mm so they will need to be reset to between 0.7 and 0.8 mm.)
 
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What other maintenance is being done ?-----Does tell tale hose come off the side of the block or the top ?-----New water pump impeller ?
 
Tell tale outlet has been modded to the top. I changed the impeller six months ago. Changed the gear oil and o rings last week.
 
As an aside, I made a muffler to lessen the annoyance to my neighbours.


Seems to create good back pressure and idles well.


Will using this end badly?

IMG20210111152252.jpg
 
timguy said:
Sweet, you should patent it. Got a video clip of it in operation?
Click to expand...

No video Tim, but if you'd like to see one I'd be happy to make one for you, let me know.

Im also considering attaching a hose and feeding it into a bucket of water for more sound deadening.

Any idea if using this will damage my engine?
 
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