Correct Plug Wires and Coil for Volvo Penta AQ125B?

[71satellite]

Hello everyone,

I just bought my first boat last week (1986 Bayliner Capri 205 Cuddy, with a Volvo Penta AQ125B engine and 270 outdrive).

I've worked on old cars and motorcycles before (I'd like to think I am fairly competent in the field of automotive mechanics), but am new to the boating world. This forum has been a great resource, but I haven't been able to find a definitive answer to the following question:

What is the correct type of coil, and spark plug wires, to be using for my motor?

When I bought the boat, the coil was bad (leaking oil out the tower), so I took it to a parts store and purchased a replacement. The original said "use with resistor/resistance wire", so I bought one that said the same thing. My understanding is that a points-style ignition requires the correct type of coil (I switched to electronic ignition in my old car about 10 years ago, so I don't remember much about points-style distributors).

Well, now that the boat is running (new coil, and new points and condenser, was all it took) I'd like to perform a proper tune-up. When I priced out the Volvo replacement wires at $200 Canadian (yup, TWO HUNDRED DOLLARS), I thought that I would look into a universal-fit Accel wire set instead. In reading through this forum, as well as the Accel website, I'm concerned about buying the wrong wires.

Did the Volvo AQ 125B come from the factory with "resistance wires"? I read an article indicating they were originally carbon-impregnated linen (not sure if that is true or not). If that is the case, and if I have a coil that requires "resistance wires", should I therefore be buying the wires that do NOT have a copper core (e.g. the Superstock 4000 series with the "conductive high resistance carbon graphite suppression material")? Or does it matter for an inboard motor?

Maybe the first question should be "is it correct to be using a coil that requires a resistor/resistance wires" with my motor? I have no idea where the old coil came from, or what was there before it - I'm making the broad assumption that the previous owner installed the correct part. I did notice that the spark from the high-tension coil wire is NOT a strong blue colour, it is orange. The motor still starts easily and runs smoothly, but I am wondering if perhaps I'm not even using the right coil for my motor.

Also, some posts on the forum suggest that my motor might have come with a ballast resistor. I'm very familiar with those (I have a 1971 Plymouth), and I've looked all through the engine compartment but have not found a ballast resistor. Am I correct in believing that my motor DID NOT come with a ballast resistor? Or am I missing an important part of the ignition system?



Okay, sorry for droning on. I would really appreciate some definitive answers to these questions, and I thank you in advance for taking the time to help me out.

Have a great day,
Chris

 

[71satellite]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Hi again,

I guess everyone is busy getting their boats into the water - but it would be great if someone could share their opinion on this topic.

I've read a great deal of very informative posts from "Don S"...if you're out there, feel free to weigh in!

Thanks in advance,
Chris

 

[captmello]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Welcome.

I'm not Don S. but I like to help when I can.

Here's a link to the aftermarket plug wires on Iboats. You will see there are some less expensive wire sets.

http://www.iboats.com/Volvo_Penta_Premium_Spark_Plug_Wire_Kits/dm/*******.271417974--**********.399298402--view_id.270223


I glanced at the wiring diagram for your engine and there is no mention of a ballast resistor. What is the purpose of a ballast resistor? I'm still learnin'

Do you have a manual for you engine and drive? How is your outdrive? Good to go? The outdrive is what you'll find different than any other machine you've worked on. You'll want to do some mainenence on that as well.

Let us know how your repairs go.

 

[71satellite]

Re: Using Accel universal wires for "high resistance" coil on Volvo AQ125B?

Re: Using Accel universal wires for "high resistance" coil on Volvo AQ125B?

Hi there,

Thanks a lot for your reply, and for the link. The American $ prices on the link correspond to the Canadian $ prices I get up here (not too far from Toronto, Ontario), at $135 CDN for the Mallory wire set. I just can't get over paying more than $40 PER WIRE!
I've considered getting parts shipped from the US, but with exchange plus duty, there isn't much of a savings.

To answer your questions:

A ballast resistor controls the current (voltage? I think it is current) fed to the coil, which in turn controls the current/voltage of the spark that fires to the distributor.
I agree, there is no mention of a ballast resistor in any wiring diagram I've seen for my motor. So I believe that I need to use "high resistance" spark plug wires to avoid melting anything down in the ignition path.

Regarding manuals, I have downloaded any of the Volvo-related stuff that I could find (including the outdrive owners and service manuals, the engine owners manual, diagrams that I've found in the forum, and lots of parts diagrams from Russell Marine). There are no Volvo dealers close to where I live, and the "local" marinas only have the Clymer manual which from what everyone indicates isn't worth the paper it is printed on. Eventually I'll order the engine service manual from Volvo, but I've been getting by with what I have so far.

My outdrive, and everything else, seems to be working great actually! I brought the boat home, got it running (new coil, new points/condensor, and "quick rebuild" of starter to unseize the internal corrosion), and actually took it for a test drive on Tuesday.
It took about 5 minutes of driving around backfiring/missing for it to sort itself out (boat had sat for 12 years prior to me purchasing it....there's a pretty good story to go along with it but it is too long for this post) and then it ran quite smoothly.

Interestingly - after about 25 minutes of driving around, I was idling out in the lake, went to apply throttle, and the boat stalled. I couldn't get it started again until I found the problem:
The rotor has a funny "two piece metal" design (any rotor I've ever seen has a one-piece metal conductor) to the electrical conductor on top, and it was very hot to the touch and looked corroded. I pried the little metal cap off the top of the rotor, used sandpaper to clean it up, and then the motor fired right up again.


Needless to say, I ordered a new cap, rotor, and spark plugs yesterday. I wanted to make sure the boat actually floated and ran before I started putting money into a full tune-up, but now I'm confident this boat is worth working on.

Before putting it in the water for the first time I changed the engine and outdrive oil, and put a new drive bellows on (holy crap, getting that helmet pin out is REALLY hard!), but other than that and the previously mentioned items I haven't done anything to it...yet.

Any old boat that has been sitting will have its share of problems, here are the current ones:

-the starter solenoid, although it engages the gear, does not pass current to the starter motor so I have to jump the terminals manually. THe solenoid doesn't seem to be user-serviceable, so I think I'm going to have to buy a new one. I'm going to pull the starter and take everything apart one more time to see if I can get it working.

-the tilt control doesn't function at the switch (tilt motor works fine when I hook it directly to the battery, however). I've replaced both relays, but other than a "click" nothing happens. I have to trace the wiring to find the problem.


Other than that, the boat just needs a really thorough cleaning, and a part of the plywood floor replaced. Not too shabby.


Anyways, that's a lot more information than this thread really requires. Back to the original question....hopefully someone can respond with some advice on using Accel (or other) universal wires with the coil and points ignition that I currently have.


Have a great day,
Chris

 

[mkast]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Look in the NAPA Marine catalog for your marine parts.

 

[71satellite]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Hi there,

Thanks for the suggestion. I looked up the part on Napaonline.com, but when I called my local Napa dealer they informed me it is a "non stock" part they'd have to special order from the US, with a 3 week delivery time!


I've been reading more and more about plug wires, from the sounds of it as long as I go with a carbon core or copper core or stainless core (NOT spiral core), everything should work fine.

I've also found a way to test the resistance of the primary side of the coil to see if it is a "ballast coil" )1-2 ohms resistance) or a "Standard coil" (3 ohms resistance), so I'm going to give that a try.

Perhaps I've been worrying about nothing....I just don't want to burn out my points.
I'm starting to think I should just buy an Accel coil, Accel wires, and one of those electronic conversion kits form Hot Spark.


If anyone has tried aftermarket wires on old ignition systems and has some anecdotal advice, I'm all ears.

Chris

 

[captmello]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

the tilt control doesn't function at the switch (tilt motor works fine when I hook it directly to the battery, however). I've replaced both relays, but other than a "click" nothing happens. I have to trace the wiring to find the problem.

Pull the cover off the black box and pull the small rectangular box in the center out and make sure the little button on the bottom is working. That is the tilt limit switch and can stick. When you replace the cove do not overtighten the long center bolts as they will interfear with the limit switch as well. Just tighten them enough that the box does not slide up and down. It will still turn.

You may have read up on this already but...

Good to hear you've tackled the ujoint bellow, very important.

 

[71satellite]

The Answer!

The Answer!

Hey everyone,

Well, it took a 20+ minute phone call with Mallory Marine Technical Support, but I got my answer:

It seems that the coil that was installed when I bought my boat was not the correct coil. Mallory makes a replacement coil for the Volvo Penta AQ125B, and it includes an internal resistor (part # 9-29707).

The tech guy at Mallory was really knowledgeable. He confirmed that without an external ballast resistor, the existing coil was overloading the ignition system (causing the rotor to burn up, and likely causing the points to burn out previously, which is why I had to replace them to get the boat running).

We then discussed wires, and he confirmed that pretty much any wire set will work (advising to stick with an RFI-suppressing set), as long as you have the correct coil OR coil + resistor setup. No need to hunt around for special "resistor" wires if the coil setup is correct.

So, I bought a set of Accel 8.8 carbon/silicon wires (on the advice that the copper and stainless aren't the best choice for marine applications) and will custom-fit them this weekend.

I hope this information helps someone else down the line.

Chris

 

[clippercraft_tom]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Can you post the URL for the wire set after you verify it works for you?
I have a need for a set of wires.
Thanks!
-Tom

 

[71satellite]

Re: Correct Plug Wires and Coil for Volvo Penta AQ125B?

Hi Tom,

The wire set I bought is an Accel 8028 (8.8 mm Graphite Core FRI Suppression Universal Fit). They work great, aside from one small hitch:

The set (at least the one I got) had 8.8 mm distributor cap boots, but the boot that was meant for the coil tower appeared to be an 8 mm boot! I was going to buy a replacement 8.8 boot, but lucked out at a garage in the area where a guy had a spare left over from a previous wire set he'd made.

Not sure if I had a wrong part in my box or what...but once I put the wires together they looked, and worked, great.

Chris