Spark plugs for 1975 25 hp--L-4-J?

[Motor Boater Bill]

I'm helping a fishing buddy who recently bought a boat with a 1975 Chrysler 25 hp (model 252HB). I found a parts list on Mercruiser.com that recommends CHAMPION L-4-J plugs. The motor came with J plugs in it, which I believe are shorter than an L plug. Just want to make sure we put the right thing in it. The plugs go in on an angle, so I expect reach is critical.

Also, any other info on good links for info and parts on this motor will be appreciated.

Many thanks!

 

[JUSTINTIME]

Re: Spark plugs for 1975 25 hp--L-4-J?

42-FS144227 is the oem number

 

[Motor Boater Bill]

Re: Spark plugs for 1975 25 hp--L-4-J?

Thanks, Justintime. I can't find any cross reference online that works with that oem Chrysler part number.

I did look up the L4J on the Champion site and they don't list it, but they recommend an RL82C as an alternative. However, if I follow their application chart, it leads me to two different plugs, either a 5933 for standard use or a L86C for racing application.

Anybody got a thought on this?

 

[steelespike]

Re: Spark plugs for 1975 25 hp--L-4-J?

I'd go with the 5933 with the resistor, should help stop interference with other electronics in the boat.

 

[Motor Boater Bill]

Re: Spark plugs for 1975 25 hp--L-4-J?

Electronics? We don't need no stinking electronics!

Seriously, the only thing even close to electronics on his boat is a trolling motor! The "depth guage" is looking over the side, and the "fish finder" is a panther martin on 6 pound test! Radio? We just sing 'cause we're so dad blamed happy to be fishing! And GPS? Well the river only runs in two directions, upstream and downstream...

Is the resistor the only difference between the 5993 and the "racing" plug? Just curious.

 

[eurolarva]

Re: Spark plugs for 1975 25 hp--L-4-J?

L4J plug was discontinued by champion. The best cross reference plug is the Champion L82C and gapped at .030.

 

[Motor Boater Bill]

Re: Spark plugs for 1975 25 hp--L-4-J?

We put in the new L82C plugs and she fired right up. Now we'll have to see how it does on the water. Thanks!