Texasmark
Supreme Mariner
- Joined
- Dec 20, 2005
- Messages
- 14,795
Short history. Bought this used rig last summer and didn't like the performance. Problems to me were transitioning from 2 to 4 was rough and after getting on 4 it took awhile to clean the plugs out so that I could get WOT RPMs. Once they cleaned out, with the prop I selected I was sitting right on 5250 the setting of the RPM limiter module.....on a cool early spring day.
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Changes I made were new filters, both main and fine (for 3 and 4), fuel pump kit,new fuel line and bulb, spark plug type, and an operational change. Additionally I was supposed to be getting conversion by the time I hit 2k RPM and it was delayed out to just under 3k.
I installed a new accelerator pump for 3 and 4 and watching the movement of the linkage it seemed to me that if I cut the recommended gap between the plunger and the throttle linkage cam from the recommended 0.030" to something as small as I could get it, without rubbing on the linkage cam (0.020 was my number) I could get acceleration to occur sooner in the RPM band.....basically made up for some wear and tear on (slop in) the throttle linkage since the year model is 2002.....and it did.
After that it was on to the plugs. Not to get too involved here but I had converted to Iridium plugs in other engines like lawn mowers and such besides the fact that my 2011 Silverado and 2009 Honda Element came standard with them...same plug actually, and was aware of their virtues.
Looking at my plugs, they weren't dry like plugs operating in the proper heat range look, regardless if 2 or 4 stroke engine installation (personal experiences). In my mind, if I could keep them dry, when I punched out and expected full performance at WOT, I would have it......and I did. In looking up NGK Iridiums, off their www, and comparing to my OEM NGK BP8-N-10 (10 is for .010 larger electrode gap.....0.040) I decided to go with the next higher heat range.....7 rather than 8 for NGKs since heat increases with the lowering of the number. Couldn't find them available but 6 was....as it turned out this was the right amount.
I installed 4 Iridium IX, NGK stock # 4085, type BPR6HIX....R for resistive which is what I found available and that's ok. That plug comes gapped at 0.030 so I carefully gapped them out to the specified 0.040....very carefully as the center electrode is very fragile and NGK warns you you could break it if careless.
Then, taking a note from back in the '60's in Merc's Fisherman series of small HP. outboards, their slant design was for two reasons which were ease of slipping over logs .....vs OMCs gearbox bulge, and in slanting the block, excess fuel didn't puddle at the spark plug and aid in fouling when trolling for long periods like occurs in boats fishing the great lakes with their kicker engines. So, any time I am off plane, the engine is tilted slightly forward (tilted out) and I assure you, you can have it trimmed/tilted in (powerhead low in the rear) and watch/listen to the performance, er ah vibrations, and just tilt it up till the rear is 10-15 * high and in less than a minute she just settles down and purrs like a kitten.
With these changes I can remain in off plane conditions for a significant period of time and when you want it it's there, both in getting up on plane for cruising or hammering down for WOT.
Last, after buying the current EPA must have football shaped squeeze bulb vs the old Merc. OEM diamond shaped bulb that worked, I had a problem with the check valve working properly in the bulb. I don't boat frequently and any time I wanted to use the boat, I had to pump and pump and pump to get fuel back up from the tank and into the engine for a firm bulb to start.
Got on ebay and bought an aluminum check valve for a few bucks and installed it between the bulb and the fuel tank. No more pump and pump. Went out yesterday and took about 3 squeezes and the bulb was firm after having been sitting for over a month.
So, today I am a happy camper. My 2+2 is as fine a machine as I ever operated.
Oh, and for a data point, back where I mentioned the setup had me at the 5250 RPM limit on a cool day, water temp like 55F air 65F (recalling because when I selected the prop I was wondering about loss at summertime temps), yesterday when i was out, the air was 90, the water 81 and my WOT RPMs were down 200 to 5050. So on the weather effect on performance....air was pretty dry in both instances, 200/5250 = 3.8% RPM loss for a 65/90 = 28% temperature increase everything else pretty much the same.....all the above were included at the time I took the data point earlier this year.
HTH
----------------
Changes I made were new filters, both main and fine (for 3 and 4), fuel pump kit,new fuel line and bulb, spark plug type, and an operational change. Additionally I was supposed to be getting conversion by the time I hit 2k RPM and it was delayed out to just under 3k.
I installed a new accelerator pump for 3 and 4 and watching the movement of the linkage it seemed to me that if I cut the recommended gap between the plunger and the throttle linkage cam from the recommended 0.030" to something as small as I could get it, without rubbing on the linkage cam (0.020 was my number) I could get acceleration to occur sooner in the RPM band.....basically made up for some wear and tear on (slop in) the throttle linkage since the year model is 2002.....and it did.
After that it was on to the plugs. Not to get too involved here but I had converted to Iridium plugs in other engines like lawn mowers and such besides the fact that my 2011 Silverado and 2009 Honda Element came standard with them...same plug actually, and was aware of their virtues.
Looking at my plugs, they weren't dry like plugs operating in the proper heat range look, regardless if 2 or 4 stroke engine installation (personal experiences). In my mind, if I could keep them dry, when I punched out and expected full performance at WOT, I would have it......and I did. In looking up NGK Iridiums, off their www, and comparing to my OEM NGK BP8-N-10 (10 is for .010 larger electrode gap.....0.040) I decided to go with the next higher heat range.....7 rather than 8 for NGKs since heat increases with the lowering of the number. Couldn't find them available but 6 was....as it turned out this was the right amount.
I installed 4 Iridium IX, NGK stock # 4085, type BPR6HIX....R for resistive which is what I found available and that's ok. That plug comes gapped at 0.030 so I carefully gapped them out to the specified 0.040....very carefully as the center electrode is very fragile and NGK warns you you could break it if careless.
Then, taking a note from back in the '60's in Merc's Fisherman series of small HP. outboards, their slant design was for two reasons which were ease of slipping over logs .....vs OMCs gearbox bulge, and in slanting the block, excess fuel didn't puddle at the spark plug and aid in fouling when trolling for long periods like occurs in boats fishing the great lakes with their kicker engines. So, any time I am off plane, the engine is tilted slightly forward (tilted out) and I assure you, you can have it trimmed/tilted in (powerhead low in the rear) and watch/listen to the performance, er ah vibrations, and just tilt it up till the rear is 10-15 * high and in less than a minute she just settles down and purrs like a kitten.
With these changes I can remain in off plane conditions for a significant period of time and when you want it it's there, both in getting up on plane for cruising or hammering down for WOT.
Last, after buying the current EPA must have football shaped squeeze bulb vs the old Merc. OEM diamond shaped bulb that worked, I had a problem with the check valve working properly in the bulb. I don't boat frequently and any time I wanted to use the boat, I had to pump and pump and pump to get fuel back up from the tank and into the engine for a firm bulb to start.
Got on ebay and bought an aluminum check valve for a few bucks and installed it between the bulb and the fuel tank. No more pump and pump. Went out yesterday and took about 3 squeezes and the bulb was firm after having been sitting for over a month.
So, today I am a happy camper. My 2+2 is as fine a machine as I ever operated.
Oh, and for a data point, back where I mentioned the setup had me at the 5250 RPM limit on a cool day, water temp like 55F air 65F (recalling because when I selected the prop I was wondering about loss at summertime temps), yesterday when i was out, the air was 90, the water 81 and my WOT RPMs were down 200 to 5050. So on the weather effect on performance....air was pretty dry in both instances, 200/5250 = 3.8% RPM loss for a 65/90 = 28% temperature increase everything else pretty much the same.....all the above were included at the time I took the data point earlier this year.
HTH
