LA3

1988 454 Magnum. Merlin heads. Was running the boat about 4500 rpms. Noticed a lose of power. Came off plane. Had a miss at idle. Boat would not plane off again. Give it gas and it would start to plane off then secondary kicked in and boat lost power. Finally got to plane off after long long time and only using 1/4 power. Ran great on top end and turned 4500rpms. Pulled out. Ran on ears on land. Had a miss and ticking noise @1100 rpm. No where else is it noticable. But, the motor is running rough. Whole boat is shaking. Changed plugs. Checked cap and rotor. Some moisture. Nothing. Ticking noise went away. Then the motor got hot and ticking came back. Again only at 1100 rpms. Still have shake. Something is not right. Any help for a lost soul. Missing yet another boating weekend. Thanks in advance for any and all help.

KNOT-RIGHT

Some possibilitys.

Try to determine which cylinder is not firing.
while idling pull wire one at a time off dist cap
until you find the one that does not cause engine to stumble.
put a ohm meter on the suspected plug wire. compare it to another
wire.
How did your original plugs look?
Try compression check.
If the tick comes and goes try
Pulling the valve covers and run it.
Check for a broken spring.
loose rocker.
Possible collapsed lifter.

Approach it in a systematic way and you will find the problem.

Good luck
Gerry

alcor

What Caveman said, wires and cap to start. I had a similar situation and found a rocker arm loose. Apparently it would jump off the top of the valve stem then back on causing the tick and missing problem you described. Let it go long enough and you'll learn about cracked poly nuts and if your lucky (like I was) when the nut splits in half, half of it will lay in the top of the head and the other half might make it through the valley and to the oil pan without trashing a cam or engine. Good luck and let us know what you find after checking a few of these items.