Spark plugs Expert - Please

[cloumar]

Can someone tell me what regular gap plugs I could use to replace the surface gap plugs of my 1998 Force - 75hp, I am doing more often slow peed and mid cruising at around the 4000 RPMs and also trolling and I am really tired to replace plugs fouled by oil, by the way I am mixing with Synthetic oil. Can I use the L77JC4 to replace the L76 any similar experience ?<br /><br />Thanks <br /><br />Smokey

 

[12Footer]

Re: Spark plugs Expert - Please

heat range and gap potentials are so critical in outboards, that most manufacturers void warantees over replacing with other than those recommended . A too hot plug will cause rapid heat buildup and bore a hole in a piston in short order. Too cold, and you'll have twice the fouling problem, and in both cases, may be causing the coils or CD pack to operate out of it's range, thus shortening thier life greatly.<br /><br />I feel your pain tho, as most of the water I operate in is "Idle Speed Only", due to manatees.<br />I must decarb after every other outing, and a new set of plugs is kept in the boat bag.

 

[cloumar]

Re: Spark plugs Expert - Please

Thanks 12Footer,<br /><br />But I saw in some forum that some guys gave the link for a web site where there is a listing for Evenrude/Johnson spark plugs and often you could see that the replacement for L76V or QL76V (surface gap)is the L77JC4 or QL77JC4 (regular type)and those plugs are matching with just about the same size engine that I have, this is why I am asking if some ever tried those in Force engine.<br /><br />Smokey

 

[rickdb1boat]

Re: Spark plugs Expert - Please

I believe and I could be wrong about this, but if the heat range and plug reach are right(Very important), I see no reason you could not try an alternative plug such as the Champion QL77 JC4 or similar NGK gapped at .040. I would call a dealer and see if he has any recommedations on an alternative plug to be sure.. I would also say that most times this is a carb related problem, rather than a plug problem.. As was mentioned, heat range is also a BIG consideration. You may also try a slightly hotter surface gap plug..I assume you are using NGK BUZHW plugs now?

 

[cloumar]

Re: Spark plugs Expert - Please

Thanks Rick,<br /><br />Yes I am using NGK - BUHW and this is where I am having problem, because NGK don't offer much or no choice for different heat range with the surface gap plug. So since the recommand plug is L76V I think that L77 JC4 is in the same heat range, unless I am deadly wrong (?)<br />Question: why you believe that I may have a carb problem ? Don't forget that this type of engine has no oil injection system so I am using premix at 50:1 - <br /><br />Smokey

 

[rickdb1boat]

Re: Spark plugs Expert - Please

Could be running rich at low speed or idle. I don't know if the force has adjustable low speed needles, but if so, I would run them in a 1/8 turn at a time, each the same, and see if this helps. If not, try another 1/8 turn in. Just a thought as I am not real familiar with the force motors.. Others will know for sure...

 

[eurolarva]

Re: Spark plugs Expert - Please

If you change plugs to a regular plug versus a surface gap plug another thing you need to consider is the distance of the piston to the tip of the plug. If you put a regular plug in there is there going to be enough clearence for the piston so it dont slam into the plug. I agree with 12 footer. Stay with what the manufacture recommends. If you troll alot get a trolling motor or a kicker motor

 

[blueskiiies]

Re: Spark plugs Expert - Please

The best article I've found so far on reading plugs. It's long with some inapplicable information in the beinning but much is relevant and well explained. <br /><br /> http://www.strappe.com/plugs.html

 

[rbyates]

Re: Spark plugs Expert - Please

I have a 75hp Force with the same spark plug fouling problem. Did you have good results with the alternative Champion plugs??

 

[Albatross]

Re: Spark plugs Expert - Please

Hi from Australia. I have a 75hp Chrysler 1978 and regularly run at under 2000rpm for approx 1 mile on 50:1 pre-mix from my mooring to open water. I have tried BUH and BUHW and have experienced exactly the same problem. I clean my plugs every 2 trips. If anyone fined a solution, I would be keen to know. By the way, these plugs are $10 each down here.

 

[roscoe]

Re: Spark plugs Expert - Please

Well my motor must be the exception.<br />1995 Force 70.<br />Cheap walmart or Pennzoil oil at 50:1<br />I've had only used 1 set of plugs in 6 seasons and have never fouled one.<br />I decarb once a year and then wipe the plugs off. I do have a spare set, but they've never been out of the box.<br />Also, the compression still reads in the mid to upper 130's.<br /><br />Using the BUHW plugs.<br />I don't troll with this motor as it pushes the boat way to fast.<br /><br />Just a thought, Do you have the proper thermostat in your motor?