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Another spark plug question

R

rmm

Regular Contributor
"Following up on a previous th

"Following up on a previous thread, I just checked the manual and specifies RV8C or MR44T OR use RV9YC for severe duty. The previous logic on the reasoning for the colder plug makes sense and appropriate for my use with many hours at trolling speed or cruise speed.

Someone stated above that "Y" in Champion specifies a cold plug, but I thought a higher number (9 vs 8) specified a hotter heat range?

Is the RV9YC comparable to a MR43T or MR44T? Also what is the MR 43TS?

Thanks"
 
Thanks goingto switch to the m

Thanks goingto switch to the mr43t and see how it runs. Would still like to know the answers tough. Thanks

The ACDelco site has little info.
 
"MR43T is a "cold" plu

"MR43T is a "cold" plug. A cold plug is what you would want in a marine engine. The heat range of the plug refers to the ability of plug to dissapate heat away from the electrodes much like the fins on an air cooled engine draw heat away from the cylinder. During prolonged operation, which is more than a few minutes, the main concern is to reduce the literal burning away of the electrodes in the heat of the combustion chamber.

Conversely, "hot" plugs are helpfull mainly in automobiles that are run a few blocks at a time, say on errands within the neighborhood. In those cases the hotter heat range allows the part exposed to the combustion chamber to heat up more so as to have a better chance to burn off carbon that might cause plug fouling."
 
Hence the hotter plug for a bo

Hence the hotter plug for a boat that see's alot of time at idle speeds 600 to 800 rpm range on "Harbor Cruises". My engines are raw water cooled and never moves the temp gauge above 125 degrees even after 4hours at 18-20 knots.
 
"..."My engines are raw wa

"..."My engines are raw water cooled and never moves the temp gauge above 125 degrees even after 4hours at 18-20 knots."

That is bad news! Your engines need to warm up enough to burn off the moisture in the oil. Those motors should run at least 140 - 150 'F when warmed up. Otherwise, you'll not only have fouling problems, sludge will build like crazy inside the engines.

Suggest you replace the thermostats.

Jeff"
 
No thermostats just block off

No thermostats just block off plates.According to original owner that i bought it from its been this way since 1966
 
"Uh, better get some thermosat

"Uh, better get some thermosats! You should run at about 143 degrees in salt water or 160 degrees in fresh water."
 
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