Re: 70hp idling characteristics?

[Don]

OK, the first thing you need to get familiar with on this engine is the "QUIKSTART" system…Quikstart automatically increases the timing when the engine is first started cold and is running below 1100RPM. This system is supposed to make the engine easier to start and less fussy during warm up. Quikstart disengages once the engine reaches about 100 degrees, or it can also "time out" after a few minutes (depending on pack vintage) in cases of thermostat problems or extreme cold conditions.
So, what does Quikstart sound like when activated….Well, it really sounds like the engine is misfiring at idle, because the timing is going back and forth between its advanced/cold setting and base setting. Why is this you ask? Why doesn’t the engine just have a high idle during quikstart operation? The quikstart is set to automatically turn off when RPM reaches 1100, this is so the engine can be shifted in and out of gear while quikstart is on without damaging the gearcase or ramming the dock. So, when the engine first starts cold (and is in idle position), quikstart will advance the timing bringing up the RPM, but the RPM will probably exceed 1100, so the quikstart will drop out…But, the engine is still cold, so quikstart will engage again, and this ping pong session will continue at idle until the engine reaches about 100 degrees or the powerpack times out.
The other thing to keep in mind is that quikstart will engage everytime the engine is restarted for about 5 seconds, regardless of engine temp.
So, you can see that it is very important that quikstart is off while you are trying to set base timing or you are going to see the timing light bouncing back and forth and get confused, I’m thinking this is what you are seeing now, which is why you are having trouble setting base timing.
The other confusing thing here is that we are dealing with base timing setting that are "after top dead center". I think the base timing setting for this engine is 4 degrees ATDC. Keep in mind that 6 degrees ATDC is retarding the timing, not advancing it… 2 degrees ATDC is advancing the timing from its base setting. So, with all this conflicting stuff going on, it is easy to get confused trying to set up sync/link on this engine.
I’m pretty sure you manual will talk about disabling quikstart and warming up the engine before trying to make the base timing adjustment. Quikstart is disabled by connecting the engine end of the white temp sender lead to ground and unplugging the yellow/red lead from the powerpack, which is what tells quikstart to come on (cranking the engine).
Next, you will need to straighten out that thermostat, the engine isn’t going to idle well running cold. Some of these later model thermostat designs are crazy complicated, so look at your manual first, and be ready for plenty of springs/cups/washer/grommets to come flying out.
Your 94 manual should be OK for the 93 model, not sure what the base needle settings are, I guess I would start at 2.5 turns out, and gradually lean them out. The pulsating you are seeing at idle is telling you quikstart is on, that is why it is idling rough and you can not set the base timing.
All that being said, these engines do idle quite nicely when set up properly, but it is very easy to get confused, you are not alone, trust me…
The larger high speed jets in these kits richen up the mixture a bit, giving a little extra cushion from detonation/preignition damage. These 56CI engines went through a few years of "mystery powerhead failures", before the design got straightened out. This is really a shame, because it is a nice running engine, and mechanically quiet.
Sounds like you have checked out TDC, so that is good. But, like Dan said, a loose inner hub magnet on the flywheel won’t show up on the TDC tool, but will show up on the timing light. I would go ahead and try to set up sync/link properly before removing the flywheel, I don’t think you have a flywheel issue, you are just seeing/getting confused by quikstart operation.
Like we have said, the trim system on this engine can give plenty of negative trim for better acceleration on short deep V hulls. But, the engine is going to idle poorly when trimmed all the way in, so I would make you adjustments at a "neutral trim setting", the follow Dan’s pointers about operating the engine.
The other thing that is going to mess with you mind here is what is referred to as the "dwell timing linkage", you will see the cheesy little spring loaded gizmo near the timer base. Now what the heck is this malarkey all about? Engineering on drugs? Well, perhaps they should have been…
Someone in the brain trust decided that these engines would run better off idle if timing advance was delayed a bit when the engine is operated just off idle. So, you will see that the engine stays at base timing for a bit while advancing the throttle. You will see this lovely feature on some of the older 90 degree V4-V6 models as well. So, you will not be able to set base timing properly unless you hold the throttle against its stop, or keep the throttle cable attached so the throttle will stay against its stop. Go ahead and just try putting the throttle against its idle stop with the cable off, you will see it won’t stay there because the dwell spring pushes it off.
OK, will get back to your other post and straighten out my mistakes there…