Wednesday 20 January 2016

OHC (Carroll) valve timing

Valve timing suggested in the 1939 manual (in red) is remarkably different
 from what is found in all other manuals
'Inlet open' in the Barnes manual (in red) is an outlier and perhaps not correct.

-JdK- I've looked up - and tabulated - the valve timing data for the Carroll OHC engines as found in the old books and as suggested by current experts. Closing of the exhaust valve seems to be critical for these engines and everyone agrees this should be set at around 42 degrees ATDC. Opening of the inlet valve comes next and should be set at 47 or 57 degrees BTDC depending on whether a silencer is used or not. Timing of the CS1 and CJ engines differs from timing of the Models 30/40. Some of the data (indicated in red) is quite different from the other numbers. Finally, note how much OHC valve timing differs from Model 18 timing (last column, bottom table).