I believe that the cams ground by Frank McGurk back in the fifties were all dual pattern, with the exhaust usually having 10 to 20 degrees more duration than the intake. I believe that there was no cylinder-to-cylinder variation. On the the inliners' BB a couple of years ago there was discussion about the merits of changing the intake timing for 1-2 and 5-6 to compensate for the unequal firing increments for those siamesed port pairs.
The discussion was all for the 230-250-292 heads. It sounded like Jim Hedrick and others have tried the tailored cam timing with some success. Nothing was said about the exhaust timing, but, as the same 240-480 degree differences in firing exist for the exhaust in the 2-3 and 4-5 exhaust ports, there may be some benefit in changing the timing for those lobes. Would this also be beneficial for a 235-261 head? Has anyone ever measured the benefits on a 230-250-292? Certainly an interesting project, if one has the smarts, time, and other resources to see it through.
Hoyt
