Hey Silvertip

[Texasmark]

NGK BP8H-N-10 plugs still running good. Light tan insulator and piston has uniform coloring across it. Was out yesterday (running my 21P prop rather than the 24) and it turned out 6400 @ 48 and kept a purring.

Mark

 

[Silvertip]

Re: Hey Silvertip

I assume you are now a "believer"????

 

[Texasmark]

Re: Hey Silvertip

Yea verily.

 

[Benny1963]

Re: Hey Silvertip

hey guys have been watching yalls post on the ngk s im running ul77vs
was going to try the ngks instead of ql77jc4s how do they do on 1985
evinrude 150 crossflow .the ql77jc4s seem ok will the ngks cause clearence issues or are they like ql77jc4s
thanks sorry to but in on thread.
but hated to start fresh thred on and issue thats run in the ground
thanks
benny b

 

[Texasmark]

Re: Hey Silvertip

On clearance, before I installed mine, I took a scale (ruler) and a popsickle stick and measured the distance from the land where the plug stops turning and compresses the washer and the top of the piston, comparing to the corresponding length of the plug. I had like twice the distance I needed for clearance.....obviously the piston has to be at the top of it's stroke.

I have a looper with flat top pistons so it was easy. If you have a crossflow with a domed piston, be sure and get the highest point that could contact the plug.

On running, as silver said, there are two things to look at...heat range correct?.....color of insulator should be tan, and piston top uniform in color...no hot spots where plug is.

If you get that you should be good to go. If not, tweak number till you get there.

I don't know what your thread size is so you might insure they'll screw in. Don't know if OB's use a common thread size or not.

HTM,

Mark

 

[Silvertip]

Re: Hey Silvertip

Benny -- if all you are doing is crossing over from Champion to NGK, that switch will not present an interference problem. The thread Mark and I had going (much of which was using private message) involved running conventional plugs instead of surface gap plugs in my personal 75 HP Merc and his 90 HP Merc. I was not having good luck with surface gap plugs in the type of service my engine saw and it now performs flawlessly with conventional plugs. I do not recommend making a plug type switch just for the sake of switching. If the plugs you are using are working ok, there is no need to change and in the case of Johnson/Evinrude, the ignition system is designed around Champion plugs of a given type and heat range and over the years I've found that they run best on Champions. Two stroke engines are very particular about plugs and an incorrect selection can cost you dearly. I have not experimented with your engine so I can't offer any advice on plug manufacturer, plug style, or heat range.