Hello Bill, good hearing from youDecember 4 2006 at 12:39 AM
|Paul (no login)|
Response to 427 Troubleshooting: Fouled Plugs
Hope all is well with you and yours.
You say the compression is strong, so that's a fair test of rings and valves.
Right off the bat I'd go after the carbs. I suspect a rich running carb with the automatic chokes being the culprit. My chokes have been wired open, I never use the chokes for starting, as I'm one of those throttle pumpers. I pump as many times as I think I need, some times more if the boat hasn't been run for a couple weeks, you get the idea. I don't like the idea of a 40-year old "automatic" device causing a rich running condition.
Under running conditions have you noticed a gas fume smell (unburned gas), which would be from an overly rich running motor? This would be especially noticed at the dock under idle conditions. If it's not the carb then it's oil that's being burned, which is not necessarily a bad thing. As engines wear, the pistons, rings, and cylinder bores all wear a little and more oil is admitted to the combustion chamber.
In addition, you can get oil dripping slowly down the valve stems too, and this may be corrected with valve stem oil control seals. If you have a high milage motor, you can adjust the plug to burn a little hotter to compensate for this too. A change of oil type and spec may help some too. If it is oil you're burning to cause that soot, you should be seeing some degree of blue smoke on the water. If it is valve stem seepage, I would think you'll see some blue smoke upon startup too. If it's oil that's causing the soot, and it seems to get worse while running around 1000 rpm, then you should be seeing some degree of smoke.
If it's a rich carb, you probably won't see much of anything but you'll smell it if you back into the slip and stand behind the boat.
I think your trusted marina mechanic was on target when he said you didn't need a valve job. You may need some valve stem seals, and it is possible to install those without pulling the head, but it's a hat trick to do it ( you have to be careful not to allow the valve to drop into the cylinder, or then you will have to remove the head. People have been known to stuff closeline into the clinder to act as a buffer.
You have great wires now, the plugs are right, be sure you are using the ballast resistor as required by Pertronix (see the Master Index 427 section on PERTRONIX if you haven't already seen the diagram). If you are sooting over while running around 1000 RPM, I think its the carb, but as with these old boat motors, it could well be a combination of two or three things working together. I'm an optimist!
I'd be interested in hearing some of the other guys chime in on this one, so gentlemen, please fire away when you are ready!