That video shows a very good way to check the cam timing at nearly full draw. The cables should come to the pencil mark at the same time. Something else I always do is, once the cam timing is set and the draw length tweaked to where I want it is to draw a line on the side of the cam edge where it passes through the limb fork. Doing this gives me a visual reference so if the cables would stretch unevenly or I'd change the rigging I can just look at those marks to get the bow back to where I originally had it set.
There are no timing mrks on the cams as they can be set to where ever you desire for a certain feel or performance. I usually advance my cams (counter clockwise in the left hand pic) by twisting the string to give a smoother draw. This removes some of the hump right before the cams roll over. It gives up some speed, which I don't care about anyway, but makes the bow feel better to me. This also shortens the draw length which can be reset using the module and draw stop.
Although you're not using pencil marks on the module to check cam timing it appears that they are pretty close by using the #5 hole in relation to the cable. There can very several reasons why you lost about 10 fps with the new cams. What many people don't do is measure and/or mark the cams and write down the specs as they originally were. Big mistake. Is the bow set to the exat same specs as before? It could very well be that the cams are not wrapped up quite as tight as the originals. Maybe the string/cables are not set to the same length as before. Is this the same rigging? Was anything added to the string? With the mods set in the #5 hole it should be at 29" draw, but have you actually measured it on a draw board? Is the draw weight the same?
Different lighting can make a difference in what the chrono reads. Still, assuming a 29" draw and computing from the IBO rating I would think your speed right now is on the slow side. The 8 grains difference in arrows only amounts to 2'/sec so that's not much of an issue. What I often find is that IBO ratings are inflated by about 20'/sec on most bows, Martin being no different. Still, you're not worrying so much about this as the amount of change from before. Maybe do some tweaking, add a few twists to the cables to get better efficiency from the cams.
Using a post on AT about optimizing the Cat cams (same as you'rs) you could twist the cables more so that the cables run right through the middle of that #5 hole. This will make the draw length a bit longer, but this can be compensated with the draw mod and draw stop. There's a good explanation on at about this. Do a search for "Optimizing Cat Cams".
Last edited by bfisher; 04-05-2012 at 05:39 AM.
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