Fouling spark plugs

[racerone]

Fact is you should not have to take the plugs out every trip for cleaning !

 

[WinnerCougar74]

They are easily cleaned so you don't have to buy new constantly.

How do you clean surface gap plugs? When do you throw them in the trash and put in new ones?

 

[CaptnKingfisher]

How do you clean surface gap plugs? When do you throw them in the trash and put in new ones?

Ive never needed to pull plugs and clean em on any of my boat motors but have done that with chainsaws that wouldn't start. Little bit of Emery cloth and some solvent to remove the dust when youre done. If youre anal retentive about things which no offense meant by this but sounds like ya might be, then check plug gaps while you've got em out and then use dielectric grease in the plug boot when reinstalling. There's also a pneumatic spark plug cleaning tool that you can buy if you're really serious about cleaning your plugs but I think Emery cloth or a points file does just as good. The bit about not filling up your gas tank the night before due to evaporation is a pretty strange theory.

I'm curious of what youre experiencing that's leading you to pull your plugs so often.. is your engine stalling or running rough? I think you're barking up the wrong tree by thinking by focusing so much on this particular engine design and the atomization of fuel and all that stuff. I suspect your carburetor is poorly adjusted

 

[racerone]

Shops used to clean / test plugs.-------Cost of the shop labour to do that today , often is more than new plugs !

 

[WinnerCougar74]

I would be more than happy to just run it but so far I seem to have to constantly mess with this motor to keep it running. I was hoping someone would know what it takes to get this Chrysler running right so I wouldn't have to mess with it so much.

 

[The Force power]

Sometimes its best to leave well alone

 

[racerone]

From a 1000 miles away it is difficult to determine what you want / need to do on your motor !

 

[WinnerCougar74]

My engine fouls plugs no matter what I do. Are these engines known for fouling plugs? Is there something I can do? Do the ignition boxes get week? 1974 Chrysler 135 hp 135 psi compression. Plugs are correct, timing is correct, new coil, points, plugs and wires. Running recreational fuel at 50-1. Idle screws at 1 turn out on both carbs. I run at low speeds a lot while trying to mark fish.

 

[dingbat]

I don't think this video accurately shows how a crossflow outboard works. On a crossflow engine the atomized fuel has to make it's way past the crankshaft. From what I understand the turning crankshaft turns some of the atomized fuel into a liquid that "pools up" in the bottom of the crankcase. This liquid fuel can be a real problem if it isn't moved out of the bottom of the crankcase. I think if the liquid fuel backs up it can get sucked in by the piston and this could easily foul spark plugs. One of the posts said that the design of the fuel recirculation system on Chryslers is a bad design. I think this could be my problem.

Whether is shows the right carb or not, it demonstrate the huge roll compression and vacuum plays in the performance of a 2 stroke.

Don’t know what factory compression is on your motor but on mine, 10-20 psi represents a 10-20% lose of compression. Cant expect that kind of loss not affect the fuel transport system

The compression in my Evinrude is plus or minus 1.5 psi. 3 psi total high to low

 

[WinnerCougar74]

Last time I checked it with a good gauge it was 137-141. Factory manual says 155-165. So that is down by around 15% Both carbs are correct and clean. I think I need to just go through a complete tune up. Check compression again, check timing, carb sync, points gap, fuel pump diaphragm, puddling hoses, etc.. All of the other hoses are marine grade and replaced this year. Thats why I needed to know if other Chrysler outboard people have the same problem. I hate trying to fix something that can't be fixed. So biggest question is do I just have to live with fouling plugs on a Chrysler outboard because that is just how they are. They aren't made for trolling all day.

 

[WinnerCougar74]

Here is a great article that confirms that fouled plugs on 2 stroke outboards is common.

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

 

[racerone]

Good luck with the tune-up.

 

[tg3690]

The one recurring theme in this thread seems to be your low compression numbers.....lower by almost 20 percent across the board? It could be that your powerhead has seen better days, and no amount of tuning or parts changing will do any good if that is the case. Just something to consider or investigate before spending a lot of time and money moving forward. JMHO

 

[Nordin]

I have not read through the whole thread right now but I have some questions.
Do you have the Motorola CD box? Do you have points in the distributor?
If you have points, is the gap set at 010 in?
Have you clean the fuel recircular/puddle drain system? Setting of the air fuel mixture screws?
If you have CD box then you should use surface gap plugs and if you have regular auto style battery ignition system you should use regular plugs with a bent electrode.
If you have points in the distributor you can convert to auto style ignition system and remove the CD box and use regular plugs with bent electrode. Maybe it will idle better for a longer time with that set up.
My experience from all 2 strokers and especially OBs is that they do not like to idle for a very long time. Air cooled 2 stroker will run hotter and will less fouling plugs. OBs is running cooler.
From my experience you should be able to idle at least for half a hour up to one hour.
The engine and plugs will not get as hot as the should when idling, oil ratio 50:1 is for WOT and when idling the ratio is to rich and the engine need to burn a rich oil mixture.
My experience of the surface gap plugs are that they fouls faster then regular plugs but they last almost for ever.
I have two other engines from another brand that use the surface plugs too. One 1970 Merc 500 with Thunderbolt ignition and one 1972 Merc 800 with Thunderbolt ignition.
They do not like to idle for to long time too. I have to open them up for a short time allowed them to clean the plugs.

 

[WinnerCougar74]

I have not read through the whole thread right now but I have some questions.
Do you have the Motorola CD box? Do you have points in the distributor?
If you have points, is the gap set at 010 in?
Have you clean the fuel recircular/puddle drain system? Setting of the air fuel mixture screws?
If you have CD box then you should use surface gap plugs and if you have regular auto style battery ignition system you should use regular plugs with a bent electrode.
If you have points in the distributor you can convert to auto style ignition system and remove the CD box and use regular plugs with bent electrode. Maybe it will idle better for a longer time with that set up.
My experience from all 2 strokers and especially OBs is that they do not like to idle for a very long time. Air cooled 2 stroker will run hotter and will less fouling plugs. OBs is running cooler.
From my experience you should be able to idle at least for half a hour up to one hour.
The engine and plugs will not get as hot as the should when idling, oil ratio 50:1 is for WOT and when idling the ratio is to rich and the engine need to burn a rich oil mixture.
My experience of the surface gap plugs are that they fouls faster then regular plugs but they last almost for ever.
I have two other engines from another brand that use the surface plugs too. One 1970 Merc 500 with Thunderbolt ignition and one 1972 Merc 800 with Thunderbolt ignition.
They do not like to idle for to long time too. I have to open them up for a short time allowed them to clean the plugs.

Wow thank you Nordin. Now this is what I need. Others have said they also need to open up the engine after trolling/searching for a long period. I will double check my tune but prolly this is the practical solution for this 46 year old outboard. Like topgun said the compression being down is also not helping. I also think if I experience fouling while out on the water, even if I clear it with a WOT run, before I go out the next time I should pull the plugs and clean them. Back in the 70's old cars needed constant attention. Remember trying to start and old car engine when it was cold out. Even if everything was perfect you still have to do gas peddle and brake peddle. Pump the gas 3 times if it was real cold. Even when warmed up they didn't always run right. I think that is what I am up against with this old motor especially with the lower compression numbers.

 

[jerryjerry05]

Compression: cold motor, get another gauge, remove all the plugs and advance the throttle to wide open, spin the motor until the gauge stops going up.
Then do it again on a hot motor.
Post the results??
Myself I've not heard compression is a cause of carbon build up?
I have experienced cheapo oil, recirc system clogged, running too cool, and needing a hotter spark plug.

 

[Nordin]

Winner I would suggest you to look at the recircular/puddle drain system. There are small screens that cloggs from carbone. They are under the "dog bone" cover at the same side as the fuel pump.
Clean them and check that the check valves closing as they should. The check valves are small pedals similar style as the reed valves but much smaller.
If the recircular/puddle drain system not working as it should you got problem with idling.
Start from there but I think you have to live with fouling plugs if you troll/idle for long periods. Smaller 2 stroker will idle for longer times compere to the lager, but this is only my own experience

 

[racerone]

?----Do parts and pieces know how big the motor is that is idling ?

 

[foodfisher]

How do you clean surface gap plugs? When do you throw them in the trash and put in new ones?

Thick rag with solvent (acetone). Screw/twist the surface till the brown stops showing.
I never killed a set of plugs. Have heard reccomendation, change every 3 years or 300 hours, which ever comes first.

 

[WinnerCougar74]

Winner I would suggest you to look at the recircular/puddle drain system. There are small screens that cloggs from carbone. They are under the "dog bone" cover at the same side as the fuel pump.
Clean them and check that the check valves closing as they should. The check valves are small pedals similar style as the reed valves but much smaller.
If the recircular/puddle drain system not working as it should you got problem with idling.
Start from there but I think you have to live with fouling plugs if you troll/idle for long periods. Smaller 2 stroker will idle for longer times compere to the lager, but this is only my own experience

Thanks Nordin, I heard a good tip, replace the recirc hoses with clear fuel hose used on 2 stroke weed whackers. Then I can watch them while the engine is running and see if there is gunk or carbon or who knows what else. I have heard that you blow and such on the hose to see if the valves close and open properly. Might do that this weekend. Thanks again.