1966 Mercury 4 cyl 65 HP Fouling plugs

[dmlane]

I have a 1966 Mercury 650 ( 65 Hp) 4 Cylinder out board. Seems to run fine, however doesn't seem to reach full RPM's and fouls all four plugs extremely bad. Also really poor fuel economy ( 25 liters in 1.5 hrs a full throttle)<br /><br />Any suggestions?<br /><br /><br />thanks DMlane

 

[achris]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Try de-carbonizing the engine, something like 'seafoam' or Quicksilver 'Power Tune'. Also the brand of oil you're using could have something to do with the amount of residue left behind. <br /><br />Chris............

 

[WillyBWright]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Welcome to iboats.<br /><br />I find that those 650s that constantly foul all four sparkplugs either need carb work, there's too much oil in the gas, or the motor is just plain wore out. Try the Power Tune. It just might help, and it's a whole lot cheaper than an overhaul.

 

[bucksaw]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Hi dmlane, I have same motor only it's a 1969 4cyl 65hp. Mine run's great, but the oil has to be mixed perfect. The old 650's are hard on gas mine is the same. Also I take the plugs out every month and clean them good. Don't know if yours has flat surface plugs or not mine does. Try spraying carb cleaner in like they said it just might help it out. I have mine on a 16 foot fiberglass I only get 30 mile per hr at best.

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Great I'll try those suggestions, where can I find sea foam, and or power tune.<br /><br />Also all the manuals i've checked recommend using a fule oil mixture of 50:1 is this correct????<br /><br />My engine uses perma gap plugs as well. I think most older Mercs do.<br /><br />Thank-you<br /><br />Dmlane

 

[achris]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Power tune can be purchased for your friendly Merc dealer. <br /><br />50:1 is correct. What brand of oil are you using?<br /><br />Perma-gap plugs are correct.<br /><br />Chris..........

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

I'm using penzoil 2 cycle oil. Perhaps theres a better oil for me to be using.

 

[achris]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

The cleanest I've found is the Quicksilver Premium Plus. And the worst..... Valvoline!

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Another quick uestion. Spent the last month waiting fora new set of plug wires for my motor.Finally got a call from the parts dealer the assenmbly was in. Went to pick them up to find the kit only included one length of plug wire, long enough to make 1 wire, at a cost of $40.00 Canadian, of course you'd still have to buy the ends and boots seperately. my question is, is the anything extra special about this wire, or can i use regular bulk automotive plug wire as a replacement?<br /><br /><br />Thanks<br /><br />Deon Lane

 

[Chris1956]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Deon, The wires on my '77 merc have a stranded stainless steel core. Automotive wires are resistor type and ar a powder. Also my merc wires have a screw end for attachment to the distributor cap. Go to www.oldmercs.com and order the correct ones for your motor. They are the cheapest. Reuse the old boots and caps if they are usable.

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Checked out the site chris1956 mentioned. Found the plug wires recommended for my engine, how ever they seem a litle short 28". The existing wires are 35-37". I could use the shorter wires if I altered the routing of the harness. Currently they are routed from the magneto, up the side of the engine, over the top, down the other side and around the engine to the plugs. I could just route the behind the throttle lever and around to the plugs. Is there any problem with this concerning overhaeting the wires etc????

 

[emckelvy]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

You have the old-style, non-electronic ign magneto, ?yes? Or do you have an "SS" model with electronic ign?<br /><br />What type of spark plugs are you running in this motor? If they're the incorrect type or heat range, it'll cause fouling. For example, if you used Permagap plugs in a std. ign., it wouldn't have a strong enough spark to fire the Permagaps and would quickly foul out.<br /><br />Weak spark can also cause spark plug fouling so that's an area to look at. If you have a std. magneto, maybe it's time for new points and condenser.<br /><br />BTW this site sells ign stuff for older Mercs:<br /><br />www.oldmercs.com<br /><br />HTH........ed

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

the ignition system on this motor is the Magneto type. I've cyhanged the spark plugs with a set recommended by a locoal Merc dealer NGK 6590 buhw). I've also changed the distributor, and plug wires. inspected the points and cleaned.<br />disassembled, cleaned and reinstalled the carbs. How ever I'm not completely confident in the carb settings, or spark advance settings.<br /><br />On the topic of the condenser in the magneto. Isn't it basicall a capacitor, and if so couldn't I use a standars capacitor checker to test it. If not how do I go about testing it?<br /><br />It should be noted that new plugs, wires, and dis cap. seem to have cured my initial problem of no power at wot.<br /><br /><br />ANY POINTERS WOULD BE APPRECIATED.<br /><br /><br />THANK YOU<br /><br />DMLANE

 

[emckelvy]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Your motor requires a standard electrode-type plug, Champion J4C, with a reach of 3/8".<br /><br />So, you're saying that the Mercury dealer RECOMMENDED a surface-gap, 1/2" reach plug (that's what a BUHW is)??!!??!!<br /><br />I'd say time to find a new dealer! Not only are the surface-gap plugs causing your fouling problems, but 1/2" reach spark plugs will extend too far into the cylinder, causing hot spots, and difficult plug removal due to carbon buildup on the exposed threads. Lucky the pistons haven't hit the plugs!!!<br /><br />I'd throw a set of Champion J4C's in there, gapped at .025"-.030", and maybe it'll run better!!!!!!<br /><br />BTW, according to this cross-reference chart, the correct NGK plug for your 650 would be a B7S.<br /><br />HTH......ed

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Ed Mc<br /><br />Where are you getting bthe info on the spark plugs??? Not that I don't believe you. It's Just that I'd like to have a look at the reference material!!!<br /><br /><br />Thanks<br />dmlane

 

[emckelvy]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

OOPS forgot to post the link to the cross-reference site:<br /><br /> http://www.spark-plugs.co.uk/pages/technical/champion860-n288.htm <br /><br />The spark plug application info was from my Seloc Mercury repair manual. But any mfr's spark plug recommendation charts should give the correct info for any particular motor.<br /><br />Here's some info I found at the Champion Spark Plug home page:<br /><br /> http://championsparkplugs.com/results_appOther.asp?otherMotiveID=12906&mfid=2 <br /><br />There's a wealth of technical info at the site if you'd like to peruse. NGK etc should have similar info. I just Googled on this stuff to find it.<br /><br />HTH and Happy Boating............ed

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Ok Just took a real good look at the aervice manual for my motor. Leraned something. Never take the info passed on from a dealer as carved in stone. I discovered that it is actually recommended that I use a gaped plug in my engine instead of oa perma gap plug.<br /><br />Thanks for the info ed I'll try a set of those puppies tomorrow after work...<br /><br /><br />Regards<br /><br /><br />dmlane

 

[dmlane]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

Well Got my self a set of new set of spak plugs. Put them in the motor. Took the boat to the lake for a test run. Engine fires up great. Is idling higher than before, however now have the reoccuring problem of no power at wot. Boad doesn't want to climb out of its seat. Any suggestions????

 

[emckelvy]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

What type of boat is it, how long, and what pitch is the prop you're running on the 650?

 

[Chris1956]

Re: 1966 Mercury 4 cyl 65 HP Fouling plugs

dmlane, I will assume that your motor's compression is good and the carbs are clean. In that case, it is likely your carbs are set too lean to accelerate. If the idle is smooth enough, open the top carb idle mixture screw 1/8 turn and try to accelerate. If not smooth, open bottom carb idle mixture screw 1/8 turn and try again. Repeat sequence until motor accelerates acceptly.