ET: Engine (Twin) Effects of Cam Timing

[Keith Martin]

We prefer heavy crankshafts with light weight rods and pistons on our road race Triumphs. A light crankshaft will spin up faster but will also slow down faster when shutting off throttle. A heavy crank will keep its momentum going through the turns that helps with corner speed.
Dave Nourish made great crankshafts. I have used many of them.

 

[Nigel Spaxman]

In this link, here are David Vizzards thoughts about cam timing. He says that a 5 degree adjustment in the cam timing can make as much as a 10% difference in power. When you listen to what he is saying it does seem as though the only way to know what the right timing setting is is from dyno results, but dyno results from a very similar engine would be the second best thing. He also mentions 30 degree valve seat angles which is a subject you almost never see mentioned. (I thought it was only Vincents that had these)

 

[vibrac]

we have spent a lot of time this year on Bens dyno with ignition and carburation but changing the timing by a few degrees at a time and checking the results would mean a heck of a lot more time I suppose the only way thats practical would be to move the half time pinion one keyway and see? but logically would that be the next one (say) clockwise?

 

[greg brillus]

Move the cam one way, increases bottom end torque, move the other way, increase top end.........We are in the process of making our own roller followers and cams to suit......but this is a longer term project probably not ready until next year........ This is purely experimental, but should give good results........of course there is far more to it than just the cams/followers......I'm looking forward to it.