 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | 03-14-2005 |
| Location: | Atlanta, Georgia USA |
| Posts: | 406 |
| Status: |
Offline
|
I don't think your specific new problem is in the carbs. When I rebuilt Ron Earp's engine last year we found a similar timing problem. It turned out that when the distributor was tested it was firing all over the place.
MSD is known for their "Multiple-Spark-Discharge". Translation: A single spark doesn't fire at a 10^BTDC, rather the first one fires at 10^ then several more over something like the next 30^ of rotation.
A really cool thing to watch is uncap the distributor and rotate the engine by hand. If you watch the underside of the cap where the terminals are you will see a brilliant lightning show of dancing 2"-3" sparks.
The point is: I think your distributor has a minor wobble due to a worn bushing or slightly out of aligned reluctor. This minor alignment problem is multiplied 100x by the multiple 40,000 Volt sparks resulting in a stray misfire.
Richening the carbs to clean-up a firing problem is a very common trick but IMHO not the best solution. In my experience Spec5-9 is ridiculously too rich and I've had much better luck with Spec10. Of course I'm also running a brand new Lucas 45DM distributor.
Judson