88spl has ticking sound like arcing at lower RPMs but stops if I adv. throttle a bit

[toddschubert]

'93 88spl starts to tick like it is arcing somewhere but stops if I advance throttle just enough to change timing rod but not fuel flow. Does it around 2000 rpm.
Also used to run 5500 rpm wot and now only 4500. Sometimes it clears up and hits 5500 but when it was doing this and I hit a wake it dropped back down to 4500.
I was thinking high speed jet on the rpm problem but that would not explain ticking.
I ran on muffs in the dark and see very little plug wire arcs (normal stuff).
I checked all grounds and coil connections but it i hard to isolate where ticking is coming from.
It really does not feel like I'm loosing a full cylinder as when I pull a plug it runs very rough and does not do that while ticking or running wot.
motor actually runs great.
Any ideas?

[toddschubert]

Also cannot duplicate problem on mufs...must have load on it I gues to do this.

[oldcatamount]

Run it in the dark (without the cowling). Sounds like it's an ignition short and if you run it in the dark, you'll probably see it arching. Bad coil wire, plug wire, (or connection).

[emdsapmgr]

Oldcatamount's has a good suggestion. Look specifically to see if either of the two bottom spark plug wires are arcing to the lower cowling latches.

[toddschubert]

Wires run clear of cowling latches. What would make a tick at one timing setting but go away as timing is advanced? NO RPM CHANGE just moving throttle enough to move timing arm not fuel flow.

[emdsapmgr]

Usually an electrical shorting to ground is most noticeable at low rpm's. When you get the engine up in rpm's, the noise and the fact that the other cyls are making hp-tends to mask the electrical issue. The fact that the sound changes when you move the timer base may indicate that the wire harness is moving with the timer base movement-moving a wire away from ground. Possible it is not an electrical issue. You might want to pull all the spark plugs and visually check inside each cylinder. A pencil type flashlight is handy for looking inside the cylinders. The pistons tops should be smooth and black/charcoal in color. Cylinder walls should be smooth. All 4 plugs should look the same.

[toddschubert]

I found a spot on number 2 coil that looks like it could have been arcing. Put some insulator goop on it and will try again tomorrow
Thanks

[emdsapmgr]

Good catch! Those coils typically have very low failure rates. May be that the coil was the issue. A new coil is relatively inexpensive and and easy to replace.

[toddschubert]

Goop seems to stopped the ticking. Coil was arcing to its own housing

[TunnelRatAK]

Did this stop your RPM loss? I have a 1979 70HP that has been having trouble getting enough power to get on plane. It had plenty of power the first time that I took it out at the beginning of the summer, except it would suddenly drop down to almost idle for a second or two and then go back to normal but now it tops out before it gets there. I took the cowl off and at idle, I noticed an faint arcing sound, but I haven't been able to locate the cause yet.

[toddschubert]

Seems so. However I started running a little seafoam through gas at about the same time. I have not had the problem since but I did Goop #1 coil that had a tiny split in the rubbery housing insulation.