Some troubleshooting to ponder during winter layup. Challenger was hauled and winterized this week but a problem with plug fouling reared its head in the post season. If you can see in the attached pic, some were carbon fouled, giving me some obvious conditions for rough running. Extended idling time is unavoidable with a slow speed limit in the channel back to the marina.
Some background . . . virtually untouched engines since factory fresh in 1973 and each have giving 2100 hours of great performance. All maintenance done at the same marina by the same master mechanic since the boat was delivered there. Oil has been changed every season and neither engine has ever required additional oil to maintain level on the dip sticks. Valves were last adjusted perhaps 20 years ago, but no one is sure. Fuel is 92 octane with lead additive. Carbs and distributors were re-built 10 years ago. Both engines have always been great starters.
Paying close attention to the discussions here, we did the following upgrades late this season.
1. Upgraded to Splitfire ignition wires. This offers lower resistance than old 1970's wires. For example, the old coil wires metered at 11,480 ohms while the new Splitfire coil
wire is 370 ohms. All wires were carefully loomed and routed to prevent crossfire.
2. New Champion RF10C plugs gapped at owner's manual specs. Points, rotors and new caps along with timing.
3. Timing light confirmed fire at each plug.
At this point, plugs were still fouling with dry black soot... not on all plugs but generally about the front four on each engine. Running at 920 rpm in the channel back to the marina always seemed to add to the plug fouling situation.
Next steps.
1. Marina owner agreed to check the valves. After all these years, they were all consistently at .025 cold and .021 hot.
2. Compression test . . . all within factory specs, hot AND cold, 160 - 190 lbs. I'm presuming that this is a good test of the valves and the cylinders.
3. Installed Pertronix electronic ignition.
We were at a freeze risk last week so the boat had to be hauled. We couldn't test the new ignition out on the lake.
Mechanic's recommendation is to re-build both carbs as he found one dead accelerator pump on the port engine's carb and he's suspicious of the automatic chokes. This will be done over the winter. He has always leaned the mixture as much as he can to avoid running rich.
Though I requested a valve job if necessary, he doesn't feel that it's necessary at this point.
If you can think of any other winter projects that could improve Challenger's performance next April, any ideas would be appreciated!
As always, thanks guys, for contributing so much to the Commander community!
Bill
1973 ChrisCraft flushdeck Commander 41
Challenger
PHOTO OF THE DAY AWARD (December 5, 2006)
"The photo above showing off the motor block and spark plug wire insallation was featured as the "Photo of the Day" on December 5, based upon it's composition, clarity, color, and relevance to the discussion at hand. Nice job, Bill!
Paul,
forum moderator
Reference comment added, the link below is from Professor Toth's Plug Wire 101 class (there will be a pop quiz in the morning):
http://www.network54.com/Forum/424840/message/1142905538/