Correct plug heat range for 360

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low compression 318 360 take a look at
RC12LYC
RFN14LY
super extended tip was developed for smog but really improves missing at idle
there are several other numbers
 
toolmanmike said:
Yep, just depends where you look. You apparently have a FSM. Is that a car or truck engine?
Click to expand...
That's the '73 Dodge Chassis - no truck info.
I figured that's about as early as might be relevant to a stock 360 in a car.
The stock applications I've seen for the N9Y plugs is the 340. Didn't pull my '67 FSM off the shelf to check the 273 4 bbl. Figured it wasnt really relevant. Only reason I went FSM at all was the number of bad experiences I had with box store parts counter people whose 'book' showed a 12 or 14 for the '68 340. And I've had similar issues with the '85 AMC 360. The factory did not use the same plug for all years, but the counter 'books' show just one plug.
 
Mattax said:
That's the '73 Dodge Chassis - no truck info.
I figured that's about as early as might be relevant to a stock 360 in a car.
The stock applications I've seen for the N9Y plugs is the 340. Didn't pull my '67 FSM off the shelf to check the 273 4 bbl. Figured it wasnt really relevant. Only reason I went FSM at all was the number of bad experiences I had with box store parts counter people whose 'book' showed a 12 or 14 for the '68 340. And I've had similar issues with the '85 AMC 360. The factory did not use the same plug for all years, but the counter 'books' show just one plug.
Click to expand...
I ran into the same kind of thing when I tried Autolites. I went from a 10.5/1 273 to an actual 9.6/1 after the rebuild. The factory plugs were n9y's. The exchange chart got me the equivalent to a n8y and with the lower compression it didn't like it. I could never get it to idle clean. It didn't sound right and ran rich no matter how much I leaned it out. After chasing the issue for a couple seasons I decided to change plugs and go with a n12y which is between the n14y 2 barrel plug and the n9y 4 barrel plug. Well, immediately the engine ran smoother and cleaner. They are still in there after 5 or so years.
 
fklskv said:
NGK’s are a waste. All those fancy iridium plugs etc. are made for one reason. 100,000 mile plug changes. Other then that they have no advantage. IMHO that is.
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Reading your post was a waste.
You you sum every NGK plug up to the characteristics of an iridium plug which is still better then you even understand.
dumb ah.

Try a gr4
 
Thanks all for the recommendations. I am currently running RC12LYC. Loving the smaller socket size. Car seems to like the extended tip, after this tank of gas we will see what it does to fuel economy.
 
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