Maximum Spark Advance Question?

[george3819]

I was looking at my repair manual and saw that it said that the maximum spark advance should be adjusted after a new powerhead is installed. I just put a remanufactured 1998 115 CV4 powerhead and I have no prior experience using a timing light and wanted to know if there was another way to adjust the spark advance. The engine runs good now and gets on plane pretty easy. What should I do?

 

[Seasport]

Re: Maximum Spark Advance Question?

It would pay to get the WOT timing checked. If it is too far retarded you won't be developing full power - too far advanced and your motor will run too hot and you risk damaging it.

I think that motor has the OIS optical ignition system. You can check the timing statically if you have an analyzer (which I'm sure you don't) or you can use a timing light. Using a timing light is not hard but you need to do it at WOT in the water which is tricky. You can either hang off the back of the boat at full speed or leave the boat on the trailer and back it far enough into the water to rev it in gear at full throttle.

Maybe you should get a shop to check it for you.

 

[george3819]

Re: Maximum Spark Advance Question?

Seasport is it alright to run the boat on the trailer with the prop removed. The repair manual sid not run the boat over idle when not in the water.

 

[Seasport]

Re: Maximum Spark Advance Question?

No, the motor needs to be under load or you risk blowing it up. The manual means that you shouldn't run your motor at high revs on the muffs with no load on the motor.

The idea if you want to set your timing with the boat on the trailer is to back the trailer down the ramp far enough to put the prop & water intake underwater. Then you run the motor in gear up to full revs. Sounds scary I know but you can do it (the boat should be tied down well). The alternative is for you to hang off the back of the boat with someone else driving it a full speed. Also scary but you can do this too.

With the OIS ignition system you can set the timing without running the motor using an electronic analyzer. These are expensive to buy (like $300) but I have designed a simple circuit to do this and I can supply details if you want to build one. A few of the iBoats members have built them. Takes basic electronics skills and about $20 worth of parts. Email me at Seasport1@hotmail.com if you are interested.