Merc ignition stuff 4's & 6's

[RogerH]

The first photo shows the basic parts of this ignition. I didn't have the smaller coil from the 850 in this picture. The switch box is P/N 332-2986. The small 850 coil is P/N 332-4895. You can buy the screw-in terminal ends from NAPA or Sierra. I buy Accel 3000 series solid core 7mm Si wire sets that come with 90 degree spark plug ends. These are readily available from Summit Racing for around $23 (for 8). The summit P/N's are ACC-3009 for yellow and ACC-3009B for blue.

The 2nd photo is the CDI/Rapair replacement unit. Note that the switchbox and coil are combined on the same mounting plate. This Sw.Box will not work with a Merc coil. It will work with a Merc distributor trigger or CDI's trigger.

The third photo is Larry McAfee's test set-up. You can see the die grinder driving the distributor and the spark plug pressurized chamber. You can observe the spark through a plexiglass cover on the chamber.

[John (Taylor) Gabrowski]

I have both flywheel Mariner 3 Holer 3 coil and belt drive Merc Distributor 3Holer ignition systems, I know you can't mix them up. I am looking at using the Merc belt driven for the second Cresscent (a Toronado 650) instead of what it has ,you can't get any parts for anyway so Merc it is.

As for MercéMariner discharge voltage and being told to be careful I learned the hard way using the Mariner, I know what being fried on the spot is all about thanks to a direct wired tach that works of sparkplug voltage when you throw its toggle switch! Never again will I ever do that! ever!

[RogerH]

This is the Type III ignition that Sam has been mentioning. It is definitely the way to go for overall performance. This distributor happens to have the CDI trigger as well. The wires were rotten going into the distributor, so there was no way to fix it. CDI supplies the complete base, bearings and new 4 & 6 cyl trigger wheel. The CDI trigger wheel must be used with their trigger as it is magnetic vs optical (Merc). The motor is a Mk58.

[John (Taylor) Gabrowski]

That is all a very nice aftermarket install that is for sure. What are the aftermarket parts cost globally for an engine.

I am still blessed with having a dozen or so complete overhauled P4D Merc mags with lots of spare parts so going that route for gassers is not in the cards but I sure do see the point for fuelers which can be difficult.

[RogerH]

This will be tricky at best. The $$$'s depends a lot upon your connections with friends, dealers, and eBay skill. eBay buying has really gotten hard on these items. Their demand has risen and I think that most of them are going to people that are trying to repair their 70's+ vintage motors.
I feel the distributors are the major item. Anything under $140 is great. Don't forget that everything counts - cap - trigger lead condition. Count on replacing the bearings, but everything else will probably be OK.
The switchbox is $30++ for a Merc. and it could be DOA. They are easy to bench test, but not many people know how to do that. The CDI box with coil is around $155 I think. I believe that is the dealer's cost.
Merc coils are pretty cheap but the small ones don't come up on eBay much. I find them in dealer's scrap heaps.
I have bought 4 whole 650's (4-cyl) for a steal just to "rob" the ignitions out of them.
Don't be in a hurry and you can scrounge this stuff rather reasonably. While it is more money, I'd shoot for the CDI switchbox/coil - but - you always need the distributor.

[John (Taylor) Gabrowski]

These days you can snag older Mercs and Mariners complete sans gearcases for $50.00 to $100 bux but the 3 Holers in them are at the point where there is a problem giving them away for anything tangible and usually they are top cylinder fried anyhow so its for ignitions or parts to keep another one running. Aeems everyone in the marine industry thinks them the worst of a joke and lemon on Mercs part. People still ask me why Merc discontinued the 4 banger 44s as that was their most successful engine to so many. Change for the sale of change? or just to make more dollars changing engines no matter what loyalty.

[Mark75H]

Roger, how much air pressure do you put on the spark plugs while testing?

My father had a spark plug tester that had a pressure set up like that when I was a kid.

[RogerH]

Usually we use 150psi This could be adjusted for padded motors, but the plexiglass cover will limit the amount. We really need one of the positions to have an adjustable air gap to distinguish the best systems.

[Mark75H]

Maybe a chamber with a long projected nose spark plug and an adjustable ground. There are some commercial boiler ignition spark plugs that have a very long insulated nose and a standard 14mm screw in base. I'll keep my eye out for one. If I remember correctly 100 psi was enough to blow out some junk. 150 and some extra gap should be a very good tester

[legend41]

I too am working on one of these ignitions and I would like to order the CDI complete kit. The question is where did you order from and is the kit number 114-2986K1? A second part is the linkage, on one of the pictures looks like you were able to adapt to the older Merc. Mag arm ( I would like to rotate the Ignition like the older Mag.) but it was not too clear where you attached the side Merc lever, how about another picture of that side of the motor? And last question is concerning the engines timing. Did you retard or keep the current timing you had?
Thanks for the help.