1970's Inline 6 Ignition Coil Inquiry

[Xerveras]

Greetings and salutations,

New to the forum as I am looking to bounce an idea or two off some folks. I have 2 inline 6 outboards:

Primary Outboard - 150HP Distributor Ignition inline 6 S/N 7067326 1500
Parts/Secondary Outboard - 115HP ADI Ignition inline 6 (havent pulled SN yet) 1150

The 1500 has been good but having some slight troubles as of late with ignition and discovered my ignition coil had cracked a tad (been hearing what sounds like arcing), I removed to inspect and the metal casing that was inside the rubber sleeve had cracked and a slight crack being visible in the plastic casing of the coil itself. I determined, hopefully, this is the issue and I am working to replace. I can order a new part from quicksilver for about 200ish CAD or CDI's coil/switchbox replacement which I think ive seen for 500ish on ebay (to give a price idea) or lastly (with my understanding of ignition coils as an apprentice) could a single ignition coil from my ADI motor replace the single ignition coil for my distributor motor? There is a size difference which to me may mean a difference of amount of windings in the coil or even the gauge of wire used within. I am performing tests now and comparing specs in the manual for what each coils internal resistance should be, but I am interested to see any thoughts on what I am looking at.

I know the best bet (if i had the money) would be to convert the coil and switch box as this would update the motor and probably preemptively prevent further issues, but the next option would be to purchase a new coil and install. The coil swap idea is just a hopes to save money for now until I can save up some cushioning for when I do purchase either of the other 2 options.

Kind Regards

 

[merc850]

Before you change the coil check the cap and wires, run engine at night to check for arcing wires cap etc. and the electrical connections including grounds.
I'm pretty sure the coils aren't interchangeable so go with the QS or http://store.oldmercs.com/category_s/2129.htm

 

[Xerveras]

I decided on obtaining a coil off ebay for 40-50 USD. Had the gentlemen take readings based on the manual and they were in spec and part#'s matched up. I opted away from the coil swap because of not only the size difference but upon testing the coil from the 1150 and comparing to the one from the 1500, the continuity existed between the tower of the coil and (+) or (-) whereas the 1500 states there should be none. As well as the ohms were slightly different in specs that I felt that they were too far apart to be considered viable. I also presumed that the ADI ignition works with different voltages, etc. than the distributor models and this might be the reason for different manual specs when testing the coils from both types.

 

[Faztbullet]

The earlier orange ADI coils will work as that what was used in coil update kit....

 

[Xerveras]

Sorry buds, i didnt receive any e-mail notifications about replies.

Before you change the coil check the cap and wires, run engine at night to check for arcing wires cap etc. and the electrical connections including grounds.
I'm pretty sure the coils aren't interchangeable so go with the QS or http://store.oldmercs.com/category_s/2129.htm

I have been into the distributor since then and cleaned the contacts, not much corrosion but a bit. I did test and verify my rectifier for failing and my old coil was cracked, since replacing both parts I am no longer hearing an arcing sound. I did test my start solenoid and it is showing minute voltages but i know i will need to replace it soon.

The earlier orange ADI coils will work as that what was used in coil update kit....

Yea I figured so, i just happened to have a 1150 TP with CDI and was hoping a coil might work but after talking with fellow techs at work, i confirmed I should not attempt.


My new issue now is RPM and Timing. My timing marks are all rubbed off, so I have had to measure a flywheel decal from a boat we had in for service one time (was a 1500) and reproduce the measurements, along with marking them onto my flywheel (working on little to no money atm). When setting all settings to spec as per the manual my RPM sits around 34-3600 via a coworkers timing light. Ive tweaked the idle to 800-900 for a better idle in gear as it wanted to die out around 700. To address me max timing and rpm issue, I spoke with a coworker and an old boat mechanic friend whom both said you could advance the timing gradually until you heard a ping and then backed off to get a good setting, but when i went to do that to obtain manual specified RPM @ WOT I ended up turning it out all the way and not hear a ping, and got 4500RPM at WOT (manual specified max timing at 21 degress and 5300-5500RPM).

My thoughts are that my switchbox may be firing improperly causing my spark to be out of timing and so my advance timing has compensated for that, which i am thinking i need to start saving/looking for a replacement (whither from CDI or elsewhere).

 

[Chris1956]

The missing timing decal is a real hindrance to setting the timing. I do not think you can set it properly by listening for pinging. Can you get ahold of that Merc 1500 you had in the shop again? If so, you could use a cloth measuring tape to figure out where .464inches BTDC, where 21* BTDC is and where 5* BTDC are located on the flywheel. Those are the only three timing marks you really need.

The decal is indexed by the punch mark. So measure from punch mark to the three timing marks you need and note the distance. Mark on your flywheel with white-out or nail polish.

 

[Xerveras]

Yeah its been a pain, i am thinking of searching around for what i can get from authorized parts dealers and other venues like ebay/local shops. Unfortunately I cant as its been delivered back to the customer for a while now, we do have a 1150 distributorless in our "swamp" but i assume the timing might be a bit different.

I found .464 using my caliper, it has a depth extension so I put my piston to TDC and measured. I then added .464 to my reading and rotated CCW til i was confident my calper base was sitting on the spark plug seat (as it was when i recorded TDC) and the extension was touching the top of the piston. The .464 is indented into my flywheel much like the aligntment marks for my distributor pulley timing.

I have been using measurements i have taken and others to measure 21 and 5 but each time I set to either recordings (which are nearly identical) my WOT RPM has been severely below manual spec (36-3800 to my recollection), my serial is 7067326 and I believe it to be a 1500 simply (no XS) which means my service manual spec is 5300-5800. I am rocking a 19P AL prop (considering a 17P) but i still should be seeing something relatively close to spec which I am now seeing after backing my max timing screw out to the point it doesnt influence my distributor or activates my economizer spring. I am thinking since I have no money for gas atm I will double back to recheck everything in the ways of timing, marks, lync/sync, and throttle cam actuation. Then i will be ready for another water test to ensure the above and fine tune my carb settings. My last water test with backing out the max advance got me to 4500 RPM, trim started it toward 4650 and then i began to chine walk so I backed off. Carbs were set at 3 turns out from 2 1/2 to ensure a lil more juice/lube, will be returning to 2 for my next run after my rechecking. At this point i am just concerned it may be a lazy switchbox as a fellow tech had a larson I/O with shitty top end, backfiring, and timing was out all due to a faulty/failing ignition module (which my switchbox basically performs the same job). So if thats true my timing advance is compensating for a lazy box and I have my idle set to 750-800 otherwise in gear it starts die and I have to jazz the throttle to keep 'er goin.

But the restoration continues, its a solid motor and I love it - just gotta get her purring right!

 

[emckelvy]

Something seems off here. If your boat is chine-walking, you're doing at least 50 or more. No way a 19" prop is gonna do 50+ mph at 4650 rpm. I'd be checking the accuracy of the tach if I were you. At 4650 rpm, the engine should sound like it's just starting to wake up a bit. Or is it screaming? Screaming would be closer to 5500 or 6000.

How big is the boat? That'll tell a lot as well.

I would do as the O.P. suggested and get a real timing mark on the flywheel. Then crank the motor up with all spark plugs pulled and all plug wires except #1 grounded. Plug #1 spark plug wire into a spark tester, if you don't have one of those, clamp a spark plug to a solid ground and plug #1 into that.

Then you can crank over the engine without the worry of it starting, to check Max Advance on your distributor. Having all plugs out reduces the load on the starter and she'll spin faster, increasing timing accuracy.

Static timing may only get you so far; IMHO, cranking the engine over and checking with a timing light removes all doubt.

BTW, the serial # of your motor indicates it was a Canada model, which requires a unique timing decal, P/N 37-73291. Unfortunately it's NLA and I couldn't find any on eBay, etc.

Maybe Sea-Way Marine in Seattle, they have all kinds of oddball parts: http://www.seawaymarine.com/

Failing that, you could use a degree wheel once you've established true TDC. This would be the most accurate way of reestablishing a timing mark. I would say though, that a good measurement from another motor should get you pretty much there.

Also, listening for pinging to set your timing is a good way to burn up your pistons from detonation! I had an old 100hp and the spark advance lock nut came loose one day while running the boat (my fault of course). The spark advance screw rattled out and increased max timing by at least 10 degrees. The spark plugs were purple when I checked them! Never heard any pinging, but it sure was running strong!!

Anyway, once you get a good timing mark you can be confident you won't burn your engine up. As long as it's idling good, you've got things set up well enough on the bottom end, to be able to concentrate on performance.

Back to that, depending on the boat size, you want to prop that 1500 anywhere from 5500-6000 rpm at WOT with only the driver in the boat. This ensures that the motor is not overloaded at slower speeds. The 1500 likes to rev so you're not gonna kill it by winding it up. My 1350 revved like a mad dog and it held together up to the time I sold it and many years beyond.

So, you might need more prop, just depends on whether that rpm reading is accurate. Some older Mercs took tach input off the brown terminal of the switchbox (Stbd Side) and used a specially matched, Quicksilver tach.

Newer-style, 12-pole tachs are meant to be powered off the stator output and if you have that style of tach connected to the switchbox, who knows what it'll read??!

The answer in that case is to move the brown wire off the Stbd side of the switchbox and connect it to either of the yellow stator wires at the rectifier. This provides the correct input from the 12-pole alternator, to the newer-style tach.

Anyway, that's enough blathering for now, HTH & let us know what you find..............ed

 

[Xerveras]

Something seems off here. If your boat is chine-walking, you're doing at least 50 or more. No way a 19" prop is gonna do 50+ mph at 4650 rpm. I'd be checking the accuracy of the tach if I were you. At 4650 rpm, the engine should sound like it's just starting to wake up a bit. Or is it screaming? Screaming would be closer to 5500 or 6000.

How big is the boat? That'll tell a lot as well.

Well first off its an old fiberglass lund ski boat 14ish ft long. Secondly i utilized a coworkers matco timing light (set to 2cycle 6 cyl) so its pretty accurate ( i would assume). The audible sound is much louder than when it was turning 36-3800, screaming...maybe just wanting to start.

My timing was done initially out of the water, and fine tuned in the water on the trailer and then tweaked out in the open lake. I can take your advice when i do my re-check. Ah so perhaps the timing measurements I have gotten are not spot on then, but as you say it should get me close to the sweet spot. I will try and locate a degree wheel..perhaps lookup a way to fashion my own?

Hmm...yea a fellow tech at work said checking via pinging it tough with a two-stroke and he has never heard one ping. He said looking at the plugs can help you determine if its to hot/lean etc. But yea my TP was running the best it ever has and i was obtaining near spec RPM, but at tech school people said "sure it sounds great...right up until the BANG!". Yes bottom end is pretty nice, and all my adjustments have been with just me in the boat. Tach wire does come off the switch box stbd side but like i said its a timing light and not a gauge/tach.

But anywho yes I will be doing some re-checking of my motor, setting everything back to spec and taking the advice ive gathered. I will report back probably next week after I have funds for fuel

 

[Chris1956]

OK, so an IL6 on a 14 footer. That combo should just about fly. The standard shaft length for the IL6 was 20". A lot of 14 footers would have a 15" transom. Is your motor gearcase hanging 5" below the transom? Is the boat plowing water?

You put that timing light on the plug wire from the coil to the distributor, right? That would be the place to get all the sparks counted, or does the timing light interpolate the RPM, based upon the setting and on the #1 cylinder spark plug wire?

BTW - set the timing in the shop and leave it alone. Do not tweak or adjust it on the water. You will only damage the motor, doing that.

 

[Faztbullet]

You put that timing light on the plug wire from the coil to the distributor, right? That would be the place to get all the sparks counted, or does the timing light interpolate the RPM, based upon the setting and on the #1 cylinder spark plug wire

Its always off the #1 wire ..I don't know of any timing light that can set timing off the coil wire or any engine that times off coil.

 

[Xerveras]

Timing lights operate off of the #1 cyl high tension lead.

Just an update:

I have rebuilt my fuel pump as I noticed the fuel pump operates off of #5's (i think) crank pulses to pump. I worked on a smaller O/B at work and because the fuel pump had failed leaking fuel it affected the cylinder it operated off of. Ran great, pulled plugs to check condition and #4 is clear and i saw water droplets =/. My fuel is fresh, carbs had been re done last year, fuel stabilizer (not a guarantee but something) at last tank before storage, and new fuel lines. I will drain the carbs and pump fresh fuel through to be safe but I had noticed one of my water jacket cover bolts were loose at one point so I am thinking there may be a gasket failing/failed. I hope its nothing worse than that.

Also did a cyl drop test and #4 i didnt notice much, if anything it was slight, and #5 caused the engine to rev higher which was odd but if that one affects the fuel pump I could have been seeing something along those lines. But regardless something is fishy and im getting close to my RPM loss. Also spark going to all plugs - I should hope so after all my electrical work lol.

My anti-ventilation plate is maybe 1/4 inch above the keel/transom line. but the gear case and prop have sufficient length below the boat i think. No plowing as I trim to a good angle - my trim limits are not working so i live by my own rules. I would have to argue against your "tweak in the shop - dont do it on the water" as the majority of the manuals I have used (even at work) say to do final touches/settings in the water, under normal load (ie. off the trailer, just the captain/tech).