1993 Johnson 150 60'. Plugs Question.

[James R]

This motor came to me with NGK BPR6HS plugs. They need replacing.
The manual calls for Champion QL16V or QL77JC4. I have a preference for NGK having had problems in the past with Champion. Are these NGK BPR6HS plugs a good substitute?

 

[Vic.S]

Re: 1993 Johnson 150 60'. Plugs Question.

No.

the Q in the Champion number indicates an inductively suppressed plug The R in the NGK number indicates a resistively suppressed plug

If you must use NGK plugs then the equivalent of QL77JC4 is BZ7HS-10

and the equivalent of QL16V (which are surfaced gapped plugs) is BUZ8H

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Thanks VIC S. Very helpful. I have gone with Champion as there are some discrepancies between the NGKs that you have suggested and those in the dealer catalog. Not important as the NGKs are twice the price.
All this is in an attempt to correct an overheat on the stbd bank. I have carefully rebuilt this motor. The stbd side bores were excellent and only required a light hone and new rings. The port side are now 30 over with new pistons etc. Compressions are right on. Using 35:1 to break it in having disconnected the auto oiler. Motor runs well but for the overheat and oiling up.
Thermostats have been replaced and the water pump serviced. Lots of water through the system.
It could of course be the temp sensor. I can put my hand on the hotter side but not for too long. There are no physical signs of overheat.
I may be a bit prem' on this because the new plugs may correct the problem.
If you have any thoughts on this they will be appreciated.
Thanks again.

 

[Vic.S]

Re: 1993 Johnson 150 60'. Plugs Question.

there are some discrepancies between the NGKs that you have suggested and those in the dealer catalog

The NGK number I gave is from an equivalents list. It might not be exactly the best heat rating for the engine but everything should be correct. I think the inductively suppressed plugs, indicated by the Z in the number, are a newish thing from NGK but they are what should be used rather than a resistive plug.
Important to use the inductively suppressed plugs with VRO systems I believe.

Tech explanation of the reasons behind using the Q (or Z ) plugs:

http://members.iinet.net.au/~pauldawson/iame26-spark-plugs.PDF

BTW The P in the NGK number indicates a projected core nose ... like the Y does in Champion plugs such as QL78YC

Cant help with the overheating issues but be surprised if a small change in plug type would make that much difference. Can you be sure you are getting a good water flow through both banks?. From what you say though it could be just a sensor fault. Can you measure the temp with an infra red thermometer and compare the two banks.

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Thanks again Vic S, a very informative article.
Never saw a need for a temp gun but it would be a useful addition to my shop. Will obtain one and see just what we are getting.
Thanks.
By the way this is an ex limey here.

 

[tashasdaddy]

Re: 1993 Johnson 150 60'. Plugs Question.

go back to the correct Champion plug, gapped properly. NGK and other brands are known to cause misfires.

 

[Vic.S]

Re: 1993 Johnson 150 60'. Plugs Question.

NGK and other brands are known to cause misfires.

I wonder what NGK would say about that. They are used by many if not most of the other outboard brands and are the most readily available plugs in the UK. I have a pair of Champion plugs (the originals) and a pair of NGK and do not notice any difference. IIRC the NGK ones are in use at the moment.

I wonder maybe the troubles, and reputation, has arisen because people have used the resistively suppressed NGK plugs in place of the inductively suppressed Champions. I dont know how long the inductively suppressed NGK ones have been available but certainly not for as long as the Champion one. Even now they dont appear on some of the equivalent lists. All too easy to end up with BR...... when they should be BZ...... and I dont suppose many dealers or mechanics will have read that article by Paul Watson!

My NGKs are B7HS-10 ... unsuppressed. The BZ ones weren't available when I bought them.

Other articles by Paul Watson on his website http://members.iinet.net.au/~pauldawson/index.html if anybody enjoys the reading.

As a tail note .. the only plugs I've had trouble with were Champions! The motor club at work got a whole batch of dodgy ones that were the type I was using in my car at the time. OK for a while but then started misbehaving. The supplier replaced the whole box full!

 

[tashasdaddy]

Re: 1993 Johnson 150 60'. Plugs Question.

NAPA Auto Parts Stores, has a 600 page marine parts catalog. on their computer under OMC spark plugs the even have the note about substituting other brands for Champion

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Thanks to both of you guys. I figured NAPA could do it but I needed to get this motor checked out and NAPA takes a day or so. Will go to them next time.
Update. Fitted new plugs and ran in the tub. Can't do much more than Idle or the water blows out of the tub. Plenty of water from both ports and telltale. Running in about 87 F ambient with the cover off and blipping the throttle occasionally. Checking the heads with my nice new IR Gun ran the motor for about 45mins.Temps settled out at 61C port and 63C stbd. All cylinders about the same for each side.
These temps may be good but I still need your expert opinions.
I appreciate your help guys.
Thanks.
Panthers country of course.

 

[Dhadley]

Re: 1993 Johnson 150 60'. Plugs Question.

Carb'd OMC motors are calibrated for Champion plugs. Some OMC motors are more sensative to plug heat ranges, some are less sensative. Your particular motor is fairly sensative to heat range. You can use a different brand but you'll want to make sure the motor runs rich enough for the non-Champion brand.

If you're having overheating issues your choice of plugs will be more important than usual. Now, you didn't mention how you know your motor is overheating. Did the hot horn sound off?

 

[nymack66]

Re: 1993 Johnson 150 60'. Plugs Question.

Thanks VIC S. Very helpful. I have gone with Champion as there are some discrepancies between the NGKs that you have suggested and those in the dealer catalog. Not important as the NGKs are twice the price.
All this is in an attempt to correct an overheat on the stbd bank. I have carefully rebuilt this motor. The stbd side bores were excellent and only required a light hone and new rings. The port side are now 30 over with new pistons etc. Compressions are right on. Using 35:1 to break it in having disconnected the auto oiler. Motor runs well but for the overheat and oiling up.
Thermostats have been replaced and the water pump serviced. Lots of water through the system.
It could of course be the temp sensor. I can put my hand on the hotter side but not for too long. There are no physical signs of overheat.
I may be a bit prem' on this because the new plugs may correct the problem.
If you have any thoughts on this they will be appreciated.
Thanks again.

Using 35:1 for break it in ? Is this correct or a typo ? Recommend pre mix is 50:1, break in is double or 100:1 ? Am I missing something here ?

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Hi DHadley.
The horn went off with the overheat signal. Pulling the sensor connection at the stbd head shut the horn off. Reconnected, the horn came back on. The stbd was considerably hotter than the port.
Now with the test I was able to do after replacing the plugs, the stbd is only showing 3 deg' hotter. Will take her on the lake at the end of the week, if the temps I am getting are acceptable to you guys and see how she runs.
Thanks for your input on plug sensitivity.
I hope my responses to others needs are as helpful as the responses I am getting.
Thanks.

 

[Vic.S]

Re: 1993 Johnson 150 60'. Plugs Question.

Using 35:1 for break it in ? Is this correct or a typo ? Recommend pre mix is 50:1, break in is double or 100:1 ? Am I missing something here ?

I dont know about missing something. .... ceratinly a bit shaky with the arithemetic.

If the recommended mix is 50:1 the normal recommendation for break in would be twice as much oil which is 25:1 !

 

[Dhadley]

Re: 1993 Johnson 150 60'. Plugs Question.

Using 35:1 for break it in ? Is this correct or a typo ? Recommend pre mix is 50:1, break in is double or 100:1 ? Am I missing something here ?

35:1 is about 1.5 times the normal oil which is very acceptable on pre-mix oil for break-in. 100:1 is 1/2 the normal oil ratio. The first number represents fuel, the second number represents oil. 50 parts fuel to 1 part oil is 50:1.

 

[Vic.S]

Re: 1993 Johnson 150 60'. Plugs Question.

Hell of a lot easier to work in ccs, litres and percentages (100:1 = 1%, 50:1 = 2%, 25:1 = 4%)

But the US is stuck in a time warp with ozs, pints and gallons (curious when the monetary system is decimal) and no body seems to understand percentages.

Except that of course if you tell someone they are getting a % pay rise they can always work that out!

 

[nymack66]

Re: 1993 Johnson 150 60'. Plugs Question.

35:1 is about 1.5 times the normal oil which is very acceptable on pre-mix oil for break-in. 100:1 is 1/2 the normal oil ratio. The first number represents fuel, the second number represents oil. 50 parts fuel to 1 part oil is 50:1.

Thanks for this information...

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Love it! Love it! Love it! but I am talking Temperatures, Guys.
It has been my experience that 25:1 just oils the hell out of the plugs and gets me stuck on the pond. Gentle with the break in is my motto.
Please give me your thoughts on my temperatures. I'm keeping my fingers crossed that we are good.
Thanks again guys.

 

[nymack66]

Re: 1993 Johnson 150 60'. Plugs Question.

Please do not run your engine hot, you can buy a laser thermometer at harbour freight and check also just to be sure. I have dual senders installed on mine connected to two gauges red wire in photo

 

[tashasdaddy]

Re: 1993 Johnson 150 60'. Plugs Question.

good point. i keep one of these in my boat bag. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93983

 

[James R]

Re: 1993 Johnson 150 60'. Plugs Question.

Still looking for opinions on my motor temps. My IR Gun shows 61 Deg port and 63 Deg stbd, after running in the Tub for 45Min. Lots of water from both ports and telltale. Are these acceptable.
Thanks.