spark plug help

[dfg4240]

Hi
Just bought this boat and it has the chrysler 440 engines-1978.
book says champion XJ-10Y-hard to find.
what is a good substitue and the book says size is 14mm
seems like a small socket to me and also when it comes to spark plug wires do I have to get marine type or any other good type spark plug wires thanks.
dfg4240

[Commissionpoint]

NGK BP6S or BPR6ES if you need a resistor plug.

See what Big D runs. NGK's or Delcos I bet.

[prowlersfish]

Champions work best in Chrysler's I don't recc NGK in any GM Crlsler or ford . ( car or Boat)
They do work well in japaness OB and cars . But don't seem to work in as well in the US stuff .

I will try and find a updated Champ number .

[prowlersfish]

RJ12YC ?? Big D ?

[dfg4240]

ok-RJ12YC
thanks

[prowlersfish]

You may wany to to wait and see what Big D runs and whats heat range works best .

[Commissionpoint]

12's or 14's for Champions for sure Paul.

I run the NGK's now in the Chevys. Japanese made no doubt, but they work just fine and have much better quality control than a lot of other stuff I have seen recently including Bosch. I really don't buy into the whole US plugs for US engines Jap plugs for Jap engines, etc theory. I buy heavilly into whoever is making the best quality parts in the proper spec at the moment theory. For me right now, thats NGK when it comes to spark plugs. YMMV.

[dfg4240]

You may wany to to wait and see what Big D runs and whats heat range works best .

Ok I will wait and see-no hurry right now=boat runs fine.

[prowlersfish]

12's or 14's for Champions for sure Paul.

I run the NGK's now in the Chevys. Japanese made no doubt, but they work just fine and have much better quality control than a lot of other stuff I have seen recently including Bosch. I really don't buy into the whole US plugs for US engines Jap plugs for Jap engines, etc theory. I buy heavilly into whoever is making the best quality parts in the proper spec at the moment theory. For me right now, thats NGK when it comes to spark plugs. YMMV.

I have to stand by my work as a pro . Vehicles just don't seem to run as good on NGKs ( or bosch). I have used them per custmer request , and remove them per request 2 out 3 times . But I see the same issues when using AC in toyota . Bottom line stay with OEM brand on plugs . If you have to make people happy . If your doing in your back yard then do what ever . OEM on Chrysler is Champion

[Big D]

RJ12YC ?? Big D ?

Really depends on how she's running with a given heat range and the condition of the plugs, whether they are are fouled or not; whether you need to run a hotter or colder plug. RJ12YC is ok. I'm pretty sure I'm running RJ14YC (experimented with different heat ranges) and that's what's in my manual but really, you should pull yours, inspect, then adjust heat range from there if you need to. Some original literature also suggests XJ10Y.

FWIW, I have used NGK in a lot of engines with very few failures. I still have Champion in mine but am not maried to them, just haven't had to change them for a while. They're both good plugs IMO.

[prowlersfish]

Its not that they fail its just that the engines don't seem to run as well . I also find a higher incident of misfires when monitored on a OBD II system . The system will pick up misfires you don't feel . A little high tech compared to what we have on our boats But ......

[dfg4240]

OK- I did some digging and advanced auto says the AC-85 is the exact same plug as the XJ-10y.
the Auto store here said the champion the RJ 12YC supercedes the XJ-10Y and is the same plug but better material and supposed to last longer than the XJ-10Y.
I bought the RJ12YC plugs anyway and will try them. Hey-If I run across the XJ-10Y plugs I will buy them also.
I want to replace the spark plug wires also.
thanks
dfg4240
I will have to pull the plug to make sure he has the right plug for the 440.
He has a 318 manual and I saw that the plug was an RN12YC for the marine LM318.
Anyway time and test will tell.

[Commissionpoint]

Generally you are going to want to stay away from the auto parts store when buying stuff for your boat. Spark plugs may be ok if they are the EXACT SAME ones you need, but its still better to source all of your parts from a marine supplier. For instance, you can get a starter or distributor for your 440's from Auto Zone or whomever and it will bolt right up and work like a charm until you cause a large explosion from igniting bilge fumes with a non ignition protected automotive part.

[dfg4240]

I realize that -this was just for plugs nothing else.
I know the marina has everything else ar Barretts marina .

[Big D]

Curious, has anybody here used stainless marine plugs? Thoughts?