1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

teletekman

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Hi,

So I have a 1973 Mercury 1500 Tower of Power that I didn't realize till after I bought it and got it installed on my Ranger Bass boat that my ignition components are off of either a '65 or '66 Mercury possibly an 1100. This motor from what I understand should have a power pack, single large coil & distributor made for that setup. However, mine was purchased with two automotive size coils, no power pack and the distributor for that setup. I am not sure the reason why this was switched over either.

So my question is this, even though I don't have the right setup for that year power head, will I be ok with that ignition setup or am I asking for trouble? I know since this power head requires Permagap's, I will at least have to change back to the L82C style plugs that is required for the mid sixties models. It fires right up as it is but have never really put it under any type of load yet. To replace the parts to get it right for the year and size range I am looking at almost a $1000 that I really don't want to spend right now if I don't have to. I bought it like this and unfortunately learned after the fact what I really had. Everything else on this motor seems ok including compression at about 120 per cylinder.

I'll include pictures in a while once it stops raining outside. Please let me know if I need to calrify anything I have described here.

Thanks in advance for helping out this newbie.

Sean
Madera, CA
 

Chinewalker

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Are you sure you have a 1500 and that someone hasn't swapped newer cowlings onto an older motor? I'm not sure you could even properly mount the older ignition bits onto the newer block without some serious fabrication...
 

Moody Blue

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

How are you determining the model year of your motor?
 

teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

I went off the serial number plate on the motor. I had Mercury check it out which came back as a '73. I don't have the number with me right now but when I get home I'll snap a picture of it. It doesn't look like there was much modification if any done to put this ignition setup on but the only other reason why I am questioning it is on the front of the block where I assume the powerpacks would get bolted to, you can see where the footprint would be against the alluminum and how that didn't get painted with the rest of the block. Assuming that it was like that to provide a good ground connection? Plus there is a permagap sticker near the head which I know the 60's style blocks didn't use. But again that style ignition that I have was only used in 65 & 66 according to Mercury.

I am pretty stumped on this so far....
 

Moody Blue

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Pictures are worth a thousand words. Sounds like you have a mystery on your hands.
 

Faztbullet

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Sounds like a 1100 with late model cowlings....
 

Bondo

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

I went off the serial number plate on the motor. I had Mercury check it out which came back as a '73. I don't have the number with me right now but when I get home I'll snap a picture of it. It doesn't look like there was much modification if any done to put this ignition setup on but the only other reason why I am questioning it is on the front of the block where I assume the powerpacks would get bolted to, you can see where the footprint would be against the alluminum and how that didn't get painted with the rest of the block. Assuming that it was like that to provide a good ground connection? Plus there is a permagap sticker near the head which I know the 60's style blocks didn't use. But again that style ignition that I have was only used in 65 & 66 according to Mercury.

I am pretty stumped on this so far....

Ayuh,.... Where, Exactly did ya find the number,..??

If it's on the top of the clamp housin',... I'm guessin' somebody bolted an older powerhead to a newer mid-section/ lower unit...

It was along time ago, but I remember Alota power heads would fit the same bolt pattern/ exhaust plate/ mid-section...
 

teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Okay, I was able to snap a few pictures of it when I got home tonight. The serial number I actually took off the transom swing arm mount which is 3505253. According to my service manual it puts it around a '73 1500 as was also confirmed by Mercury. I also snapped a picture or two of where the mount is for the switch box which is indeed missing. You will also see the dual coils and hopefully the distributor mounting as well. I did forget to mention that some of the wiring was replaced when I bought it since it was pretty old. However everything was put together exactly as you see it when I bought it according to the pictures.

When we bought it it did have 1500 emblems on the lower end as they looked factory, just old as well as the cowling which we have since repainted. So after reading a few of the replies again now I am starting to wonder if I do indeed have an older 1100 power head mouned to a 1500 lower end and original 1500 transom swing mount.

First off is this even possible? If this is an 1100, would everything mount up without major modifications as mine is? If this is an 65 ot 66 year 1100 block, I am currently running BU8H Permagaps which obviously aren't stated for this motor but it fired up after a few turns beautifully. But then again if this indeed a '73 then my current ignition components are wrong.

Is there any other serial numbers on the powerhead that I can verify as well?

Thanks again for all the help so far.
 

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teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Here are a few more pics...
 

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teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

And the lst two...
 

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teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Okay I answered one of my questions already. I did while I was taking the pictures, notice another serial number stamped on the starboard side of the powerhead which echoes what is on the transom swing mount. So far I do have a '73, now I just can't explain the ignition components....
 

emckelvy

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

It's definitely a 99-c.i. block. You could tell for sure if it's a 1500 by pulling a main jet plug and noting the jet size. If I recall a 1500 should be running .084 jets.

The CDI switchbox and distributor trigger assy are so expensive that they probably replaced their bad parts with whatever they had sitting around, which was the old-style 2-points distributor assy with dual car-coils.

As long as they set it up correctly, it certainly will spark, but the spark won't be as "hot" as the CDI setup. You'll definitely need to replace those Permagap plugs with the correct heat range and reach of an electrode-style plug.

Note that Permagap plugs run very cold, and 99 cubic-inch Inlines are prone to detonation. Stands to reason an electrode-type plug will increase this tendency. So you're gonna want to reduce the maximum spark advance setting (maybe by a degree or so). Around 20 deg BTDC max I reckon, maybe some of the other Merc Guru's can weigh with their thoughts on that. Plus run higher-octane fuel or even better, LL-100 Avgas if you can get it and it's not illegal to use in your area. She won't ping on that stuff!

Another reason to reduce max spark is that the "chopper" disk in the CDI distributor does not have evenly-spaced "windows", from what I recall the window for #3 cylinder is different because #3 is the most prone to detonation and spark lead is slightly retarded to help with this. The dual-point distributor fires evenly, therefore, you've really got to be careful with max spark advance.

Keep the cooling system up-to-snuff (new impeller), and remove the back-drag jets off the top of the float bowls (if it's got 'em), or plug the little black hoses (1 per carb) going from carb throat to the float bowl. Either way will disable the back-drag feature which leans out the motor at higher speeds for economy. Not a good idea to lean this motor out, the way it's set up!

The alternative would be to upgrade to the correct components, which will be rather $$$ since you're gonna have to find a complete distributor (plus the switchbox and coil, which are usually a lot easier to find than a good dist).

Until then, one possibility is to install the correct CDI switchbox and coil, and connect the dual-point distributor to trigger the CDI switchbox. This would be pretty much how the ign in CDI-powered 1100SS motors worked. You'd also have to remove the condensers since they're not used when triggering a CDI unit. This setup would have a hot enough spark to run the Permagap spark plugs.

Later-model coils for the CDI models are a lot smaller than the old orange coil which mounts over where the dual coils sit, so you'd have more options for mounting the coil. Used switchboxes and coils are readily available on eBay and other used outboard parts sites.

Failing that, you could install a pair of performance automotive coils, with internal ballast. Remove the external ballast resistors and wire up directly to the coils. This will give you a hotter spark and you may even be able to run Permagaps.

The biggest problem you'll have with Permagaps and a lower-voltage dual-points setup is plug fouling especially during prolonged idling. But the hotter coils might fix that.

Here's my last thought on the dual-points setup: They have to be set up correctly. The first set of points has to have 90 degrees of dwell (i.e. closed for 90 degrees rotation of the distributor), and the second set of points must open exactly 60 degrees after the first set of points opens. Normally this is set up with the lower half of the distributor removed (4 bolts), along with the cap & rotor. A degree-wheel is mounted on the open face of the distributor, along with a pointer to mark degrees of rotation. I have the Merc degree wheel on file if you need it (so do others at this site), or you can draw up a simple one on paper. The pointer can just be a bent piece of wire attached to the rotor shaft, easy to make.

If the points aren't set up to fire correctly, you'll get an imbalance between cylinders 1-3-5 and 2-4-6 and this can lead to poor operation or even a busted crankshaft! No fun there!!

At any rate, your 1500 would make my buddy Thom (aka Dr. FrankenMerc) proud!

Maybe it's time to search Craigslist for a parts motor, any 99-c.i. Six with CDI ign would be a good donor.

HTH & G'luck with your Monster!..........ed
 

Chinewalker

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Yep, she's definitely been the beneficiary (victim?) of some McGyver-style rigging. As Ed recommended, I'd be on the look-out for a blown motor with the correct parts. You could probably make what you have work, but it would be far easier to get the right stuff. Plus, you could probably recoup some of your investment by selling off the 1100 parts...
 

DirtyOldBoat

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

I agree - find a parts motor and ebay the stuff you've got. I needed to replace all the electronics on my '73 1500 and I found another motor that was seized up for $150. If I had to get the parts individually I would have really been nickeled and dimed to death. These motors are SO picky about their ignition system, if it ain't just right you're playing with fire.

Right now is the time to buy parts too, as soon as June gets here and people realize their boats don't run, prices will skyrocket. I've been seeing some good deals on I6 distributors lately on ebay.
 

Faztbullet

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Until then, one possibility is to install the correct CDI switchbox and coil, and connect the dual-point distributor to trigger the CDI switchbox. This would be pretty much how the ign in CDI-powered 1100SS motors worked.
The 1100SS had horseshoe trigger and doubt you can wire dual points to fire the switchbox correctly
 

gbrowne9

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

i think you have a pre 1966 block in there. it has 2 fuel pumps in the side of the block. the ignition system is 1 set of points and coil for 3 cylinders.i had a 1965 1000 that had that set up. we later robbed a 125hp for the electronic ign components.in 1966 merc went to thunderbolt electronic ignition.
 

emckelvy

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

These models of 950SS and 1100SS used the old-style distributor with dual-points to trigger a CDI box:

http://www.maxrules.com/oldmercs/Wiring/0_1965a/10.pdf

The horseshoe-type trigger distributor assy (used in the Merc 1000SS and maybe a 650-4 if I recall correctly) was different from the old-style points distributor, although the horseshoe-trigger distr itself bolted up to the distr drive in a similar fashion as the points distr.

With jumpers in the correct place, the later-style Merc CDI switchbox can be used with the dual-points distributor.

Not that this would be ideal to run a 1500, but it has been done on an 1100SS and proven to work (spark-wise, that is). The original switchboxes that came with the 1100SS are pretty hard to find.

Regarding the block, one picture clearly shows the transfer port covers of a 99-c.i. block.

HTH............ed
 

teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Thanks everyone for all the replies.

So I think I am convinced to at least get a switch box and coil as emckelvy has pointed out and maybe try with my dual point distributor to see how that works. In the mean time I'll be looking for a parts motor which none have come up with locally yet. I think I have found at least the switchbox and coil setup or what I think are the ones I need on fleabay. Can anyone tell me if these will work for my 1500?

Mercury 80 HP 1971 Outboard Electric Power Pack P N 332 2986 Fresh Water Nice | eBay

Mercury Kiekhaefer Ign Coil Part 2983A5 Casting 46307 or 53003 $80 Free SHIP | eBay

The only one I am having a hard time locating is the correct distributor setup as some have mentioned already I would have. If anyone knows of where to maybe find one or can tell me what part number I am looking for can your forward the info my way?

Thanks again!
 

emckelvy

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

The 4-cyl switchbox will work, although it won't give the correct rpm reading on a Quicksilver tach (the old-style which connected directly to the box). Modern tachs run off pulses from the alternator, so if you have a tach which connects to one terminal of the rectifier, that'll work just fine.

The coil is the correct one for CDI ignition. Here's one a bit less $$$: 332 2983A19 332 4895A5 Ignition Coil Mercury 65 HP 4 Cyl 2983A19 4895A5 | eBay

The distributor from any 99-c.i. Inline Six will work on your motor. As will a 4-cyl distributor from an "800", "850", or 85hp 66-c.i. Four. But you'd have to replace the 4-window "chopper" disc with one for a 6-cyl motor (and of course change the dist cap). Otherwise the trigger assy, rotor, and distributor drive assy are the same between those Fours and Sixes.

The OEM part number for the distributor trigger assy by itself is 3736A 23 (list price over $500, it's a little over $400 here at iboats).

The more common CDI Electronics replacement trigger P/N is 134-3736, here's a kit on eBay for 'only' $275:

Trigger Kit for Mercury 4 6 Cylinder CDI 134 3736 Replaces 393 3736 | eBay

Of course, you're not just repairing a distributor, you have to come up with an entire assy which, if you bought the individual parts, would break the bank. In most cases, if you found a dist with a bad trigger but otherwise complete, you could refurb with the CDI trigger and likely end up a lot cheaper.

But the best deal would be a dead Craigslist motor. One time I scored a seized 90hp Six complete with ign for $75! You can bet the dist alone was worth way more than that!

Here's the cheapest eBay dist I could find, no telling if the trigger is any good but at least it's complete. Too bad they cut the plug wires!

Mercury 115HP Distributor 6 Cylinder | eBay

Actually that's the only 6-cyl dist assy on eBay that I could find, period. There is another one, a complete 800 distributor, for around $265 shipped, and you'd still have to tear it apart to replace the chopper disk.

IMHO, for that money, I'd rather buy a "core" complete dist assy with bad (or unknown) trigger, pick up the new CDI trigger, install that, and have a reliable distributor that I knew wouldn't die on me on the water.

Better to refurb any dist you get, 'cause a part as simple as the bearing snap ring can break due to rust and cause the destruction of a very $$$ trigger. Ask me how I know! These dist's aren't hard to work on and the bearings & snap ring are inexpensive compared to the cost of the trigger and rotor.

At the very least, an inspection of the innards would show condition of the mechanical parts, if it turns smooth as silk and there's no rust in the trigger area, it's a good one. Then all you've got to worry about is the trigger/housing assy itself (it's all one piece).

Anyway, there's my $.02, hope it helps & G'luck...........ed
 

teletekman

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Re: 1973 Mercury 1500 I-6 with 65' or 66' Ignition Components?

Thanks for the info Ed.

Will this coil work for me?
1970 Mercury 115 HP 6 Cylinder Ignition Coil Good Used Condition Free Shipping | eBay

It says it came off of a 1970 115hp which if I understand it correctly uses the same setup I need. I am leaning towards sacrificing the $80 and getting that distributor. Asuming the distributor is good, in the mean time will I be able to use the plug wire set I have now just too make sure everything is running smooth before forking out a new wire set?

Also, can you tell me what part number I need for the correct OEM switchbox? Rather then get the CDI switchbox now, I would rather save a few $$$ just to make sure everything is at least working then I can spring for the CDI box.

Thanks, Sean
 
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