1974 115hp Evinrude cranking speed and spark

[ninefingerz]

Are these motors picky about cranking speed? If the battery is a little low, I get no spark. When it is fully charged, I get a nice hot spark. When the battery is a bit discharged, it doesn't seem to crank overly slow, but spark definitely suffers. I am wondering if I have a spark pack going out, or is this the way these engines are?<br />this engine has 1 stator, 1 spark pack, and 4 coils.<br />Thanks

 

[OBJ]

Re: 1974 115hp Evinrude cranking speed and spark

The original service manual says at least a 300CCA battery. But.....I would recommend to use at least a 500CCA battery. These puppies take a good push to get started and the better the battery the easier the engine will start.

 

[ninefingerz]

Re: 1974 115hp Evinrude cranking speed and spark

OBJ, you would suspect cranking speed rather than electrical problems? If thats the case, I will just make sure my battery is always topped up. It generally sits all winter long, and I don't get out very often in the summer, so if cranking amps is critical on this motor, I'll just have to remember that...<br /><br />Thanks

 

[rodbolt]

Re: 1974 115hp Evinrude cranking speed and spark

hello yes cranking speed on that motor is very critical. if it drops below about 300 rpm even though it sounds like its cranking over fine it may quit sparking. you can tell by trying the spark test with the plugs in as well as out. its also an indication the starter or cables need attention.<br /> good luck and keep posting but I would go for 750 or 1000cca

 

[ninefingerz]

Re: 1974 115hp Evinrude cranking speed and spark

All of the cable are pretty healthy, I think its just a weak battery, because it's been sitting. I think its a bad design when you can crank the motor over well enough to fire from a compression and fuel point of view, but the ignition system in incapable of performing the task. The motor could easily become flooded, which will only add to the problem.... I appreciate the feedback

 

[ledgefinder]

Re: 1974 115hp Evinrude cranking speed and spark

If it cranks slow with a fully-charged battery, check the solenoid before you blame it on the starter motor. The OMC ones tend to go, and mimic a bad starter.

 

[OBJ]

Re: 1974 115hp Evinrude cranking speed and spark

Wow rodbolt....1000CCA....that would push you through the water pretty good wouldn't it??

 

[rodbolt]

Re: 1974 115hp Evinrude cranking speed and spark

OBJ <br /> if there is one thing I learned hotrodding 455 olds and 454 chebbies is if ya can squeeze that monster battery in then squeeze it. nothing like 11.5/1 compression on a hot texas night behind the miller brewery in ft worth when you have a race and the engine just goes rrr rrrr r-r-r-r. not that I ever street raced that aint legal<br />I hate dead batteries worse than flat tires.and if it will spin that tired old starter and cables and solinoids even when its flooded you stand a better chance of coming home under power. I work for the local Tow Boat US capt in manteo NC quite a bit. the only thing dumber than a dead battery or out of gas is not enough two stroke oil to make it back from offshore.<br /> as far as the design it worked well if you did the maint. I get a bit jiggy when the customer blames the equipment for his or her lack of maint. a weak battery is a maint issue not a design flaw.<br /> good luck and keep posting

 

[DHPMARINE]

Re: 1974 115hp Evinrude cranking speed and spark

ninefingerz,I totally agree it is a badly designed system.But 30 years ago it was "state of the art".<br />As I recall 11.5 volts at battery,9.5 to power pack while cranking?was required.A poor starter would drain the battery below this voltage.Thus a slow crank speed and poor or no spark.<br />DHP

 

[rodbolt]

Re: 1974 115hp Evinrude cranking speed and spark

DHP<br /> by 74 with a single pack and 4 coils I think was a batteryless CD ignition, was totally self powered but had to spin about 300 rpm to generate enough voltage to activate the trigger coils under the flywheel. a cheating trick is to close the coil airgap. somewhere in all my junk I have a flywheel hub with the wheel cut off to set the air gap .<br /> good luck and if I am off a year its cause I am old

 

[R.Johnson]

Re: 1974 115hp Evinrude cranking speed and spark

Rapair makes a hub to set the air gap, R553-9702 is the part no.

 

[OBJ]

Re: 1974 115hp Evinrude cranking speed and spark

Lottsa' top shelf info in the above posts' ninefingerz. Read and believe. <br /><br />Never ever did I ever suspect you of doing back street dragracing rodbolt.....but it was a helluva lot of fun, wasn't it?

 

[DHPMARINE]

Re: 1974 115hp Evinrude cranking speed and spark

rodbolt,I think we are talking the same system.After your post I see how mine refers to the earlier 'amplifier' battery ignition.At the same time,I find the 1974 ignition also needs the voltage I suggest to spin the rpm's needed.<br />Also isn't this the sensor with the 'non-adjustable'pickups?Years ago a techrep advised me to loosen the screw and 'pry'the sensor in towards the hub.First reference I've seen to a special tool.<br />just wondering, DHP

 

[rodbolt]

Re: 1974 115hp Evinrude cranking speed and spark

hello<br /> yep same system.<br /> Igot bit bad byone in the earlynities. came in with a no start. pulled the plugs tested compression and spark. good compression 7/16ths sparks man I jumped all overcarbs.took them apart and was dismayed to see they were clean as a pin. reassembled them and still no start.<br /> removed the flywheel and inspected all the sensor and stator windings. anyway to make a 5 hour exercise in futility short I finally determined with the plugs in no spark. plugs out plenty of spark, dissasembled the starter and found a bad brush that was making poor contact. replaced brush and it fired right up. I had to eat 5 hours of my time and a set of carb kits. I dont get bit on that anymore . like I posted before. there aint a whole lot of things you can do that myself or one of my hotrod buddies did not do. I am a lucky tech in the fact that I can watch someone else get bit and learn as well .anyway to get back to the battery question. if you suspect something is wrong you can do voltage drop tests acrossed the cables and solinoids . if you dont know how to do the drop test post me back and I will talk ya through it. but sometimes just take the brush holder from the starter and clean them up.<br /> good luck and keep posting

 

[ledgefinder]

Re: 1974 115hp Evinrude cranking speed and spark

I've had the timer bases mess up at low rpm on those "powerpack" ignition in the 1973-77 V4s & I3s (a lot) but haven't had problems with the stators being able to generate enough charge, or the powerpacks being failure-prone for that matter. A failing timer base makes itself known by cutting out one cylinder at low rpms - rev it up a bit and everything's fine. <br /><br />The other problem with those 1973-77 V4s (in my limited experience) is the choke. Unless the flaps close 100% (99.94% isn't enough), the motor simply won't start. Also, the OMC starter solenoids seem to fail a lot, cutting the current so that you thing you have a bad starter motor. <br /><br />Street racing...I feel so bad for kids today not having what we had 30 years ago. Back then, when something hairy pulled in, you knew you were going to see it run hard in a few mintues - maybe for a few bucks, maybe just for fun - but it WAS going to go. These days, if you see a blown Camaro or something, there's a town cruiser right behind it. Not to trash law enforcement - it's just that times have changed. Anything risky is strictly forbidden for your own good. I'll tell you though, get even a mile offshore and you're back on your own.