At the 2011 Invasion in Winona, we discovered my ignition timing was about 22 Deg BTDC at 1000 RPM. We tried adjusting it to a more reasonable setting but it ran poorly at anything less than 22. Nevertheless I continued to drive it on my7500 mi road trip. I suspected maybe my damper /pully was mismarked, or possibly shifted on its elastomer band. I just finished checking the TDC mark on the damper/pulley and it seems correct. And it still requires about 20 deg at 750 RPM to run smoothly.
I'm looking for possible explanations. It has the Vizard mod, stroke increased from stock 3.25" to 3.35", custom pistons to maintain stock deck clearance of 0.018", but with reduced dish to achieve CR of 9.3, plus KB grind on the cam. Do these mods account for the needed advance increase?
Is it possible I have the cam mistimed? I doubt it very much, as I assembled it quite carefully, but I have no photo of the installed timing chain. It seems to me that a misstep on the chain would have a much greater effect on proper running.
For those interested in how I confirmed the pulley timing mark, I made a pair of long plastic "feeler gauges", one 0.050" and one 0.060", from sheet styrene, and inserted them into the cylinder thru the #1 spark plug hole. With a deck clearance of 0.018' and a gasket thickness of about 0.030", you have a "squish" area about 0.048". You can tell when you reach TDC, within about 5 degrees. The 0.060 feeler will not insert into the "squish" area at TDC, but the 0.050 one will. 4 deg earlier and 4 deg later the 0.060 will fit into the squish area. I used a wooden extension handle on my crank starter handle to move the crank in small steps .
Tom
I'm looking for possible explanations. It has the Vizard mod, stroke increased from stock 3.25" to 3.35", custom pistons to maintain stock deck clearance of 0.018", but with reduced dish to achieve CR of 9.3, plus KB grind on the cam. Do these mods account for the needed advance increase?
Is it possible I have the cam mistimed? I doubt it very much, as I assembled it quite carefully, but I have no photo of the installed timing chain. It seems to me that a misstep on the chain would have a much greater effect on proper running.
For those interested in how I confirmed the pulley timing mark, I made a pair of long plastic "feeler gauges", one 0.050" and one 0.060", from sheet styrene, and inserted them into the cylinder thru the #1 spark plug hole. With a deck clearance of 0.018' and a gasket thickness of about 0.030", you have a "squish" area about 0.048". You can tell when you reach TDC, within about 5 degrees. The 0.060 feeler will not insert into the "squish" area at TDC, but the 0.050 one will. 4 deg earlier and 4 deg later the 0.060 will fit into the squish area. I used a wooden extension handle on my crank starter handle to move the crank in small steps .
Tom