Whats everyone using for spark plugs

[K4282]

I have a 73 F32, came with rwc 318's, i changed the port motor after a PO blew it up and stripped it down with a good used FWC 318, I found boxes of mis plugs in the boat, one champion plug part number in the starboard motor, a different number in my port motor and a different part number at a local parts store, some looked slightly different in length

[ready123]

My manual says Champion XJ10Y with gap of .035"...

[prowlersfish]

I come up with XN9Y Champion . They have a longer reach then the J plugs . I know the big block ( 440 etc) us the J reach plugs . LOOK at the threads in the head you should be able to tell


Ready Can you recheck your info ? Mine can from a Chrysler marine manual ( online here) and my memory ( for what that's worth )

[K4282]

i believe "xj 9y" is what I found in my port motor, "xj 12y" in my starboard and a the box of random spares had bosh and champion plugs of even more part numbers

[mikeandanne]

For small block chrysler----- in our 360's we use champion rn12yc--- Mike

[ready123]

I come up with XN9Y Champion . They have a longer reach then the J plugs . I know the big block ( 440 etc) us the J reach plugs . LOOK at the threads in the head you should be able to tell
Ready Can you recheck your info ? Mine can from a Chrysler marine manual ( online here) and my memory ( for what that's worth )

Checked and I put wrong manual up..... here is the LM page which confirms your XN9Y... I have edited this post accordingly to remove any chance for confusion as time goes forward.
Here is a copy of page from manual......

[prowlersfish]

I come up with XN9Y Champion . They have a longer reach then the J plugs . I know the big block ( 440 etc) us the J reach plugs . LOOK at the threads in the head you should be able to tell
Ready Can you recheck your info ? Mine can from a Chrysler marine manual ( online here) and my memory ( for what that's worth )

Here is a copy of page from manual......
]

I see your info is for the M318 ( old stlye ) My info is for LM318 , Different heads I believe the they switched to LM in the early 70s or late 60s look at the HP , . Most LM318s are 225 hp and would take the N plugs

OP what is your HP ? or can you post a photo of you engines I can tell you if you have a M or LM

[prowlersfish]

http://www.correctcraftfan.com/Download ... Manual.pdf



sorry about the poor copy

I will try and find photos of the M vs the LM engine

[ready123]

I come up with XN9Y Champion . They have a longer reach then the J plugs . I know the big block ( 440 etc) us the J reach plugs . LOOK at the threads in the head you should be able to tell
Ready Can you recheck your info ? Mine can from a Chrysler marine manual ( online here) and my memory ( for what that's worth )

Here is a copy of page from manual......
]

I see your info is for the M318 ( old stlye ) My info is for LM318 , Different heads I believe the they switched to LM in the early 70s or late 60s look at the HP , . Most LM318s are 225 hp and would take the N plugs

OP what is your HP ? or can you post a photo of you engines I can tell you if you have a M or LM

You are correct I posted the old manual, which still might suit the OP if his engines are that old.
I have changed my post to show the new manual for LM engines.

[captainmaniac]

I think the Champion 'replacement' part number is RN9YC