1983 Evinrude 235: Using Surface Gap Plugs - Moderated Discussion Areas

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Repairs/Mods
  1983 Evinrude 235: Using Surface Gap Plugs

search | FAQ | profile | register | author help

Author Topic:   1983 Evinrude 235: Using Surface Gap Plugs

Narragansett Outrage posted 07-09-2009 11:34 AM ET (US)
I've read several threads here about the correct plugs to use in various motors. I [want] to replace the Champion plugs in my 1983 Evinrude 235. The current plugs are Champion with the "J" shape, and given what I've read, I assume that these are the correct plugs for this motor. However, interestingly enough, pretty much every site I go to to look for the correct spark plugs for this engine says to use surface gap plugs (which seems to be what Jeff advocates).
So I guess that's what I'll do; they're going to be NGK.
jimh posted 07-09-2009 09:16 PM ET (US)
Surface gap plugs are ~~only~~ recommended on Evinrude motors when the motor will be running at high speeds almost all the time, such as in racing applications.
Cf: http://continuouswave.com/whaler/reference/BRP/SparkPlugChart2008.pdf
jechura posted 07-09-2009 10:44 PM ET (US)
jimh, your chart may be wrong as for the recommend plug for the 235's. All the research for plugs on my engine point to only the surface gaps. This even includes Doug from Lockmans.
Narragansett Outrage posted 07-10-2009 08:48 AM ET (US)
Jim - thanks - that chart, though, is what I've seen while surfing the web... unless I'm misreading it, it calls for surface gap plugs (actually says it next to the plug numbers), and while it says to use Champion, I can't see anything on there that talks about only installing them for racing. What am I missing?
Whaler_bob posted 07-10-2009 11:00 AM ET (US)
IIRC... surface gap plugs run "cold" as compared to standard plugs. I think they're more suited to hi-speed, heavy use conditions where oil fouling isn't a concern.
Tohsgib posted 07-10-2009 12:20 PM ET (US)
Do not use surface gap if you troll or have long no wake zones...OMC's don't like that. On the fllip side I was VERY surprised to see my 1981 Mercury 7.5 uses Champion QL77JCY or whatever they use in OMC's and not a surface gap. I did not believe the guy at the store and went home and looked it up...weird.
jimh posted 07-11-2009 11:31 AM ET (US)
My comments about using surface gap plugs are based on the recommendation in the service manual for my motor. If they do not apply to the 235-HP V6 I would be surprised. The best indicator is the outcome from using them. Give the surface gap plugs a try. Perhaps they will improve performance. However, there is a general tendency in human nature to look for an improvement after investing time and money in the modification. You should establish some sort of metric to test so that you don't mislead yourself from your natural tendency to find improvement after effort expended.
pglein posted 07-11-2009 11:50 AM ET (US)
In all the research I've done, the the recommended plugs for my Johnson V6 150 are surface gap. The reference charts don't specify the type, the just happen to be surface gap.
My assumption was that this was because of piston clearance issues. I've heard of people ruining these motors because they installed plugs with an extra 1/4" of thread on them.
Jeff posted 07-11-2009 11:00 PM ET (US)
I ran NGK Surface Gap plugs exclusively with my 235 Evinrude without any problems. I even had a lot of no wake usage in my normal outtings. (for a 4-5 hour ride 1.5-2 would be no wake usage).
I prefer using the surface gap plugs as they are easy to clean and carry aboard as you never had to have a tool to check/set the gap.
Here is an article Jimh posted about how well and smooth the old motor ran.
http://continuouswave.com/ubb/Forum4/HTML/004986.html
jimh posted 07-12-2009 10:33 AM ET (US)
I am confused about reports that the Chart (linked above) has incorrect data. As I read the chart, for the 235-HP motor it says:
235-->1978 - 1985--->QL16V or UL77V Surface Gap
My interpretation is the chart recommends surface gap plugs. Is the chart wrong? It seems to be consistent with what others are saying.
The QL16V plug is a "fixed gap" or surface gap plug. In my Evinrude literature for my 225-HP V6 the QL16V is noted as being an alternative plug for "sustained high speed" use.
I am afraid I have caused some confusion, I should have said:
"Surface gap plugs are recommended on Evinrude motors when the motor will be running at high speeds almost all the time, such as in racing applications."
Narragansett Outrage posted 07-20-2009 07:02 AM ET (US)
Well, I can now say most assuredly that surface gap plugs are not for my 1983 Evinrude 235. It may very well work for a VRO system, but not pre-mix like my set up.
The motor ran a little rough at idle, but we made it out of the harbor and out the channel. When I tried to increase rpm to get to plane, the motor hesitated and wanted to die. I then put it in neutral and gunned it a little bit, immediately engaged the transmission, and off we went. Ran very well at speed, but then when slowing down, it really wanted to die - it had no intention of idling.
My stupidity - the family wanted to get off the boat at the beach near our house, so I motored them in, let them off... and then couldn't get it started again before being pushed back to the beach (and having to raise the motor). I then battled the surf for an hour, pushing the boat out as far as I could, attempting to put the motor down and start it, but always ending up back at the beach before I could give it more than a few tries. Then the batteries started dying....
Finally ran home and pulled the old Champion plugs out of the garbage, ran back to the boat, changed them out, had a friend at that point who helped me push the boat out past the break. Vroom, started first time.
No more surface gap plugs for me on this motor, and no on-beach drop-offs either.
L H G posted 07-20-2009 01:44 PM ET (US)
All seven of my Mercury conventional 2-stroke outboards, 90-200Hp range, 1984-2008, both cross flow and loop charged, use surface gap plugs. I wonder what the design difference in the engines between OMC and Mercury is that different types of plugs are used.
jimh posted 07-22-2009 07:59 AM ET (US)
This anecdote about starting problems with surface gap plugs in an Evinrude 235 cross-flow engine is interesting. I wonder if there might be a problem with the spark generation. I mention this based on the following observation:
I was watching an outboard technician use a spark test fixture to diagnose an engine problem. A spark test fixture is a test device which has leads that connect to the spark plug wires of an engine, and then convey the voltage to ground via a choice of paths. The test fixture can be set to convey the voltage via a resistance or via an air gap. When set for air gap, the technician can observe the spark being generated for each individual cylinder. This can be useful in making a diagnosis of problems related to the spark.
The test fixture air gap is quite large, probably about 0.5-inch! A motor with good spark generation will produce enough spark voltage to jump this distance, even when just cranking over at low speeds with the starter motor. I watched with surprise as I saw a V4 motor produce ample voltage to jump the air gap. While watching, I thought of this surface gap plug discussion. If there is enough voltage to jump 0.5-inch, there ought to be enough to jump the gap in a surface gap plug without any problem. The gap there can't be nearly as long as the air gap in this tester.
I suspect that problems with getting spark in the situation mentioned above were aggravated by the plugs being wet with fuel. Too much unburned fuel in the combustion chamber can probably create a situation where the voltage on the spark plug bleeds off without arcing over. Also, I wonder if the spark voltage might be weaker than normal, also leading to a problem getting spark across the wider gap of a surface gap plug.
Also on the tester: you can compare the spark generation among the cylinders by observing the strength and color of the arc across the air gap. This gives a nice indicator and diagnostic tool for finding a weak spark situation in one cylinder.
Narragansett Outrage posted 07-22-2009 08:43 AM ET (US)
I think that you'd be correct in assuming that in my case, the plugs were becoming fouled with the fuel/oil mix.
When running with the regular j-plugs, if I removed them immediately following a long wot run, they would be a tan color and dry. If I idled the motor for a few minutes and removed them, they would be wet and dark. I'm assuming this is normal. In any case, the motor ran fine.
I didn't get a chance to remove the surface gap plugs after a long run, so I can't comment on what they looked like - but when I removed them to replace them, they were wet and dark. I'd say, therefore, that the j-plugs have a better ability to operate in that oily environment than the surface gap plugs.

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: 1983 Evinrude 235: Using Surface Gap Plugs
Narragansett Outrage	posted 07-09-2009 11:34 AM ET (US) I've read several threads here about the correct plugs to use in various motors. I [want] to replace the Champion plugs in my 1983 Evinrude 235. The current plugs are Champion with the "J" shape, and given what I've read, I assume that these are the correct plugs for this motor. However, interestingly enough, pretty much every site I go to to look for the correct spark plugs for this engine says to use surface gap plugs (which seems to be what Jeff advocates). So I guess that's what I'll do; they're going to be NGK.
jimh	posted 07-09-2009 09:16 PM ET (US) Surface gap plugs are ~~only~~ recommended on Evinrude motors when the motor will be running at high speeds almost all the time, such as in racing applications. Cf: http://continuouswave.com/whaler/reference/BRP/SparkPlugChart2008.pdf
jechura	posted 07-09-2009 10:44 PM ET (US) jimh, your chart may be wrong as for the recommend plug for the 235's. All the research for plugs on my engine point to only the surface gaps. This even includes Doug from Lockmans.
Narragansett Outrage	posted 07-10-2009 08:48 AM ET (US) Jim - thanks - that chart, though, is what I've seen while surfing the web... unless I'm misreading it, it calls for surface gap plugs (actually says it next to the plug numbers), and while it says to use Champion, I can't see anything on there that talks about only installing them for racing. What am I missing?
Whaler_bob	posted 07-10-2009 11:00 AM ET (US) IIRC... surface gap plugs run "cold" as compared to standard plugs. I think they're more suited to hi-speed, heavy use conditions where oil fouling isn't a concern.
Tohsgib	posted 07-10-2009 12:20 PM ET (US) Do not use surface gap if you troll or have long no wake zones...OMC's don't like that. On the fllip side I was VERY surprised to see my 1981 Mercury 7.5 uses Champion QL77JCY or whatever they use in OMC's and not a surface gap. I did not believe the guy at the store and went home and looked it up...weird.
jimh	posted 07-11-2009 11:31 AM ET (US) My comments about using surface gap plugs are based on the recommendation in the service manual for my motor. If they do not apply to the 235-HP V6 I would be surprised. The best indicator is the outcome from using them. Give the surface gap plugs a try. Perhaps they will improve performance. However, there is a general tendency in human nature to look for an improvement after investing time and money in the modification. You should establish some sort of metric to test so that you don't mislead yourself from your natural tendency to find improvement after effort expended.
pglein	posted 07-11-2009 11:50 AM ET (US) In all the research I've done, the the recommended plugs for my Johnson V6 150 are surface gap. The reference charts don't specify the type, the just happen to be surface gap. My assumption was that this was because of piston clearance issues. I've heard of people ruining these motors because they installed plugs with an extra 1/4" of thread on them.
Jeff	posted 07-11-2009 11:00 PM ET (US) I ran NGK Surface Gap plugs exclusively with my 235 Evinrude without any problems. I even had a lot of no wake usage in my normal outtings. (for a 4-5 hour ride 1.5-2 would be no wake usage). I prefer using the surface gap plugs as they are easy to clean and carry aboard as you never had to have a tool to check/set the gap. Here is an article Jimh posted about how well and smooth the old motor ran. http://continuouswave.com/ubb/Forum4/HTML/004986.html
jimh	posted 07-12-2009 10:33 AM ET (US) I am confused about reports that the Chart (linked above) has incorrect data. As I read the chart, for the 235-HP motor it says: 235-->1978 - 1985--->QL16V or UL77V Surface Gap My interpretation is the chart recommends surface gap plugs. Is the chart wrong? It seems to be consistent with what others are saying. The QL16V plug is a "fixed gap" or surface gap plug. In my Evinrude literature for my 225-HP V6 the QL16V is noted as being an alternative plug for "sustained high speed" use. I am afraid I have caused some confusion, I should have said: "Surface gap plugs are recommended on Evinrude motors when the motor will be running at high speeds almost all the time, such as in racing applications."
Narragansett Outrage	posted 07-20-2009 07:02 AM ET (US) Well, I can now say most assuredly that surface gap plugs are not for my 1983 Evinrude 235. It may very well work for a VRO system, but not pre-mix like my set up. The motor ran a little rough at idle, but we made it out of the harbor and out the channel. When I tried to increase rpm to get to plane, the motor hesitated and wanted to die. I then put it in neutral and gunned it a little bit, immediately engaged the transmission, and off we went. Ran very well at speed, but then when slowing down, it really wanted to die - it had no intention of idling. My stupidity - the family wanted to get off the boat at the beach near our house, so I motored them in, let them off... and then couldn't get it started again before being pushed back to the beach (and having to raise the motor). I then battled the surf for an hour, pushing the boat out as far as I could, attempting to put the motor down and start it, but always ending up back at the beach before I could give it more than a few tries. Then the batteries started dying.... Finally ran home and pulled the old Champion plugs out of the garbage, ran back to the boat, changed them out, had a friend at that point who helped me push the boat out past the break. Vroom, started first time. No more surface gap plugs for me on this motor, and no on-beach drop-offs either.
L H G	posted 07-20-2009 01:44 PM ET (US) All seven of my Mercury conventional 2-stroke outboards, 90-200Hp range, 1984-2008, both cross flow and loop charged, use surface gap plugs. I wonder what the design difference in the engines between OMC and Mercury is that different types of plugs are used.
jimh	posted 07-22-2009 07:59 AM ET (US) This anecdote about starting problems with surface gap plugs in an Evinrude 235 cross-flow engine is interesting. I wonder if there might be a problem with the spark generation. I mention this based on the following observation: I was watching an outboard technician use a spark test fixture to diagnose an engine problem. A spark test fixture is a test device which has leads that connect to the spark plug wires of an engine, and then convey the voltage to ground via a choice of paths. The test fixture can be set to convey the voltage via a resistance or via an air gap. When set for air gap, the technician can observe the spark being generated for each individual cylinder. This can be useful in making a diagnosis of problems related to the spark. The test fixture air gap is quite large, probably about 0.5-inch! A motor with good spark generation will produce enough spark voltage to jump this distance, even when just cranking over at low speeds with the starter motor. I watched with surprise as I saw a V4 motor produce ample voltage to jump the air gap. While watching, I thought of this surface gap plug discussion. If there is enough voltage to jump 0.5-inch, there ought to be enough to jump the gap in a surface gap plug without any problem. The gap there can't be nearly as long as the air gap in this tester. I suspect that problems with getting spark in the situation mentioned above were aggravated by the plugs being wet with fuel. Too much unburned fuel in the combustion chamber can probably create a situation where the voltage on the spark plug bleeds off without arcing over. Also, I wonder if the spark voltage might be weaker than normal, also leading to a problem getting spark across the wider gap of a surface gap plug. Also on the tester: you can compare the spark generation among the cylinders by observing the strength and color of the arc across the air gap. This gives a nice indicator and diagnostic tool for finding a weak spark situation in one cylinder.
Narragansett Outrage	posted 07-22-2009 08:43 AM ET (US) I think that you'd be correct in assuming that in my case, the plugs were becoming fouled with the fuel/oil mix. When running with the regular j-plugs, if I removed them immediately following a long wot run, they would be a tan color and dry. If I idled the motor for a few minutes and removed them, they would be wet and dark. I'm assuming this is normal. In any case, the motor ran fine. I didn't get a chance to remove the surface gap plugs after a long run, so I can't comment on what they looked like - but when I removed them to replace them, they were wet and dark. I'd say, therefore, that the j-plugs have a better ability to operate in that oily environment than the surface gap plugs.