BUP thank you so much for your response

I wish you were around my neck of the wood -- would love to buy you dinner for all the help you have been to me over the years!


3pointstar

I had them in my pre blown engine and heard that they were good for boosted applications due to them being easier to fire (wither or not that is accurate I don't care). I took them out based on what makes them better for automotive applications, their ability to maintain high electrode temps to burn off deposit s. This is not desirable for an engine under constant heavy loads. Could lead to pre ignition. I'll take a standard plug electrode that can dissipate heat better.

Actually I am in some boat owners woods. I have free flights and do not charge for USA traveling to the boat owner. I do charge for rent car, gas and 25 bucks per day for food plus marine service labor and parts along with any nights stay expenses. Some boaters pick me up at the airport and some I even stay at their lake houses while working or consulting about their boat. Granted I am not talking about 100s of customers nor even a 100 here but enough to travel at least once or twice a month thru out the year.

I even have one customer in Spain. Yes Spain - he has the money to pay whomever but in Spain it seems he can not find a tech to get his boat running correctly no matter who works on it. The main problem with his boat was - a shift in gear switch short problem once in a while. I found it and now he thinks I am golden. Anyways kind of a funny story because he had about 6 or 7 Spain techs work on it and spent 1000's without a real fix to his problem.

Double platinum plugs were designed specifically for waste spark ignitions. It has to do with where the spark originates, since waste spark types have half the system running reverse polarity. Copper plugs are your best bet in a distributor type ignition system.

The AC 41-932 is a dual platinum spark plug that Volvo and Merc and Indmar all used. Here is the SB about changes in the spark plugs from Merc.

http://ww2.justanswer.com/uploads/RO...2519_SPARK.pdf

The 41 - 932 has been changed - one of the reasons was because people gapped them inwhich caused misaligning the double platinum tips causing misfires.

You know what BUP, I would agree and say my above comments would not fit with those plugs and a majority of iridiums. Take a look a the DENSO plugs, much finer wire which my comments would apply to.

http://s14.postimg.org/qyit37frh/41t_Uwi38z6_L.jpg http://s8.postimg.org/neuceszjl/61q_...b_L_SL1050.jpg

can you explain the reverse polarity thing.i remember years ago mallory made a dist called the rev pole.

On a waste spark ignition, one coil is used on two plugs. Both plugs fire at the same time. On one plug, the spark originates from the electrode to the ground, then travels through the block and goes from the ground to the electrode on the other plug.

Would a DUI distributor have enough fire for the iridium? It's not cool over plug but it does have some juice to it. I'm asking because my boat came with iridiums. It's just a n/a 502.

Yes, they will fire. My main points about not using platinum or iridium on distributor systems, and in boats for that matter, is that their objective is longevity. They are not as conductive at copper and are easier to foul. High voltage systems rely on the voltage to ensure they can burn through any build up. With a distributor, extra resistance in the plug and lead to rotor to cap crossfiring. In all honesty, unless you have over 1000 hours on the engine, they aren't meeting their longevity value anyways. Run copper, save money, be happy.