MCM 165/3.7L/470 spark plug readings

natemoore

natemoore

Master Chief Petty Officer
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Jun 13, 2009
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#1 and #2 spark plugs: text book normal condition

#3 and #4 spark plugs: covered in carbon

Engine performance is good.

Possible causes?
 
S

stonyloam

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Mar 13, 2009
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Re: MCM 165/3.7L/470 spark plug readings

natemoore said:
#1 and #2 spark plugs: text book normal condition

#3 and #4 spark plugs: covered in carbon

Engine performance is good.

Possible causes?
Click to expand...

Read page 1C-2 troubleshooting in your #8 manual.
 
EddiePetty

EddiePetty

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Re: MCM 165/3.7L/470 spark plug readings

...and after you have finished reading Terry's reference.

Verify that all four existing plugs are the same manufacturer, tip type and heat range.
 
natemoore

natemoore

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Re: MCM 165/3.7L/470 spark plug readings

I suppose that rich fuel mix etc wouldn't apply since just a couple are fouled. So....

"bad ignition leads"....guess that's another name for spark plug wire? Mine are old. Looking for replacements this evening. Did the Pertronix/Flame Thrower conversion recently.

Stony, didn't you do the conversion? Which Flame Thrower plug set did you use? Did you have to buy a $50 crimping tool?
 
S

stonyloam

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Re: MCM 165/3.7L/470 spark plug readings

natemoore said:
Stony, didn't you do the conversion? Which Flame Thrower plug set did you use? Did you have to buy a $50 crimping tool?
Click to expand...

You mean plug wires? I went with OEM Mercruiser plug wires. Not cheap, but they fit perfectly "plug and play" LOL.
 
natemoore

natemoore

Master Chief Petty Officer
Joined
Jun 13, 2009
Messages
844
Re: MCM 165/3.7L/470 spark plug readings

stonyloam said:
You mean plug wires? I went with OEM Mercruiser plug wires. Not cheap, but they fit perfectly "plug and play" LOL.
Click to expand...

Oh! You haven't heard of those Flame Thrower spark plugs??? They added 20 hp to my engine! :p
 
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