Quote:
Originally Posted by turbobill
On an engine with a factory setting of 7.5 degrees before top dead center, I might venture up to 15 BTDC or so in 2 or 3 degree increments. While you have the timing light on the engine, make sure the centrifugal advance advances the tinming as the RPM's increase.
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Several weeks ago I did some inspections and adjustments as you suggested and I didn't find anything unusal. I must admit, I was nervous about running the timing up twice per the manual recommendation; however, it was a good experience. I learned a lot and I believe there were positive results. Thank you.
I double checked my dwell setting, which was 33 degress and my timing was 7.5 degrees at 500 RPM (very close to what I set two years ago when I pulled the motor, resealed and painted it).
I completed two dozen timed runs on the highway with my factory settings. I adjusted the timing to 10 degrees and completed the same two dozen timed runs and the results were very, very close when compared to the runs with the factory settings. I then adjusted the timing until the engine started running rough, which was approx at 20 degrees. The RPM change from 7.5 degrees to approx 20 degrees was an increase of 60. I barely backed the timing off and the engine was smooth again, so I continued to back it off until approx 16 degrees, then I locked it down. My RPM was now 550, so I readjusted to 500. Once again, I completed the same two dozen timed runs and they were consistently faster. I also noticed the gas pedal seems more sensitive/responsive than before.
I've driven it a couple hundred miles and haven't noticed anyother changes like running rough, back firing, or anything like that. I still have that slight hesitation or sputtering when holding around 30 mph, but when I punch the gas pedal, it goes. According to the Motors Manual, it states it's normal for that carb to have a little hesitation at steady cruise around 20-30 mph (if I remember correctly).
Note: I'm not trying to make a racer out of this, just want to take advantage of whatever power I can get out of that big monster.