Correct spark plugs?

[wjhuskey]

I'm going to try new spark plugs in my 1979 55 hp Evinrude to see if it helps before I start trying other things. I posted in the forum here about it starting great but dying at takeoff. The plugs in it are Champion L77J4 and that's what the tag on the wire recommends too. I went to Wal-Mart to buy Champion plugs with this number on it but the closest thing I could find to the same number is QL77JC4. These were one of the very few on the shelf that were in a "marine style" package. Will these work?

 

[Roberthill]

QL77JC4 is for a rope start engine . L77J4 is for electric start engine .

 

[F_R]

I wonder what the thinking is behind that? The "Q" plug has an inductive noise suppressor built in. What's that have to do with how it is cranked? Just asking. In the meantime, I would have no hesitation whatsoever using the Q plug in that engine.

 

[Vic.S]

The recommended plugs are L78V, which are surface gap plugs, or QL77JC4 gapped at 0.030".
If suppressed plugs are not needed L77JC4 would also be suitable

Certainly not heard any suggestion before that different plugs are required for electric or manual starting. Would also like to know the reasoning.

 

[David Young]

My 1977 70 hp Evinrude calls for L77J4 or QL77JC4 spark plugs. It had L77J4 in it but i changed to QL77JC4 because they cost a little bit more. I 'thought' they cost a 'little' bit more was because they were less likely to rust. Just a guess

 

[F_R]

They cost more because they have the radio noise suppressor in them. That's what the Q stands for. The C stands for marketing hype. Well officially it stands for copper.

 

[NAT1VE]

QL82C, L77JC4 and L77J4 can be used I am pretty sure? My 81' 9.9 runs either plugs and so does my 79' 115hp with no problems gapped at .30 for performance or .40 for trolling. When I first was given the 9.9 Rude it had one of each and ran all day perfectly fine.

 

[Vic.S]

My 1977 70 hp Evinrude calls for L77J4 or QL77JC4 spark plugs. It had L77J4 in it but i changed to QL77JC4 because they cost a little bit more. I 'thought' they cost a 'little' bit more was because they were less likely to rust. Just a guess

I think you will find that there are "marine" versions of all the plugs mentioned, They have a corrosion resistant shell and naturally cost a little more than the standard versions.

The Q plugs as F-R says have inductive suppressors. ITYWF that they were developed for the (early) OMC CDI ignition systems which do not work well with resistance suppressed plugs. They are also recommended for all motors with VRO.

 

[Roberthill]

On the breakdown of this motor it calls out two different plugs . Myself I would not want to rope start a 55 horse motor but when I seen they had these two plugs listed I posted them hoping someone could enlighten us . Rope start verses electric start ??????

 

[Vic.S]

On the breakdown of this motor it calls out two different plugs . Myself I would not want to rope start a 55 horse motor but when I seen they had these two plugs listed I posted them hoping someone could enlighten us . Rope start verses electric start ??????

This distinction seems to be only made in the original parts breakdown for 1979 models

Only L77J4 are listed for earlier models

There are various changes for later years but no distinctions made between electric and manual starting AFAICS

However the latest available official plug recommendations seem to be for L78V or QL77JC4 right through from 1976 to 1989, with no differences suggested for electric or manual starting

 

[wjhuskey]

So to sum this all up, should I use the QL77JC4 plugs in my motor that doesn't have it written on the tag? (Has L77J4 on the tag)

 

[Vic.S]

So to sum this all up, should I use the QL77JC4 plugs in my motor that doesn't have it written on the tag? (Has L77J4 on the tag)

Yes
They are the currently recommended conventionally gapped plugs for the engine

I have no doubt that L77JC4 will be equally satisfactory if you do not require or do not want to pay the extra for suppressed plugs.

 

[Vic.S]

Rats . Duplicated post deleted

 

[wjhuskey]

Yes
They are the currently recommended conventionally gapped plugs for the engine

I have no doubt that L77JC4 will be equally satisfactory if you do not require or do not want to pay the extra for suppressed plugs.

Ok I will get them put in the motor. Thanks for your help.