MCM 165/3.7L/470 spark plug readings

[natemoore]

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

#3 and #4 spark plugs: covered in carbon

Engine performance is good.

Possible causes?

 

[stonyloam]

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

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

#3 and #4 spark plugs: covered in carbon

Engine performance is good.

Possible causes?

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

 

[EddiePetty]

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]

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?

 

[stonyloam]

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

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

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

 

[natemoore]

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

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

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