Normal
The ignition timing is different for the early 371 cams from the later 431 cams. The automatic advance/retard unit on the back of the left hand cylinder head gives different advance curves for each model. This is for the early model, the later one is stamped 431.[ATTACH=full]15540[/ATTACH]Likewise, the timing marks on the crankshaft are also different. The initial advance on the early model is 5 degrees BTDC, later is 10 degrees BTDC. It is relatively simple to use a small sharp chisel through the timing sight hole to remark the crank exactly half way between the T marks and the F marks. Do it for both sets of marks.Ok, disclaimer time. Doing this resets everything to what Honda originally intended, apart from the carbs. I have never tried to run early cams with later type timing marks and/or timing unit. I suggest, if you have the patience for it, that you run the different combinations and see what difference it makes to performance and fuel consumption. If anyone has already done this, chime in now.
The ignition timing is different for the early 371 cams from the later 431 cams. The automatic advance/retard unit on the back of the left hand cylinder head gives different advance curves for each model. This is for the early model, the later one is stamped 431.
[ATTACH=full]15540[/ATTACH]
Likewise, the timing marks on the crankshaft are also different. The initial advance on the early model is 5 degrees BTDC, later is 10 degrees BTDC. It is relatively simple to use a small sharp chisel through the timing sight hole to remark the crank exactly half way between the T marks and the F marks. Do it for both sets of marks.
Ok, disclaimer time. Doing this resets everything to what Honda originally intended, apart from the carbs. I have never tried to run early cams with later type timing marks and/or timing unit. I suggest, if you have the patience for it, that you run the different combinations and see what difference it makes to performance and fuel consumption. If anyone has already done this, chime in now.
