1974 70HP Evinrude

[miichael18]

I have a 1974 70HP Evinrude Model #70473-M and on my motor it says use spark plugs UL77V but in my repair manual it says for a 1974 70472-73 uses L77J4? The UL77V seems to foul out easy after about 10 times on the lake i gotta change them. Can i go with the L77J4 even though on my enigine it says use UL77V? Will it hurt anything?

 

[Dhadley]

Re: 1974 70HP Evinrude

Youll find the number is now a L77JC4. Use the QL77JC4 if you need a noise suppression plug.<br /><br />Your good to go!

 

[miichael18]

Re: 1974 70HP Evinrude

Whats a noise suppression plug? <br />So even it says ul77v on my engine the L77JC4 will work right?

 

[DJ]

Re: 1974 70HP Evinrude

Noise suppresiion plugs have resistors in them to stop potential radio interference signals. They are not always necessary. A lot depends on how your electronic react, on your boat.<br /><br />Yes, these L77JC4 will work.

 

[miichael18]

Re: 1974 70HP Evinrude

would there be a diffrence between the UL77V and the L77JC4 as far as running wise?

 

[DJ]

Re: 1974 70HP Evinrude

The "JC4's" will troll better. Gap them at .040"

 

[miichael18]

Re: 1974 70HP Evinrude

great i notice at very low speeds mine wants to chug and die. i figure they would be more spark also since you can gap them. the UL77V you cant gap there just flat. in my book it says .030 so would .040 gap be better as far as low speeds?

 

[DJ]

Re: 1974 70HP Evinrude

yes.

 

[miichael18]

Re: 1974 70HP Evinrude

maybe they will also help out on my fuel economy. it seems to want to drink gas when the UL77V gets a little fouled. thanks for all the fast replys !