You may think how can I fine tune my cams and what advantage can I gain by tuning my cams.

In the manual there usually is a low and high limit for gapping your cams I have always wondered what this would do if I went either way. First of all the limits give you a %10 safety factor so your valves don't hit the top of the piston this is not a good thing hence the safty factor. Race car mechanics have been doing this for years so lets try some theory.

If you gap on the low side the valves will open sooner/close sooner this produces bottom end torque good for rock climbing, pulling, anything that involves power out of the hole.

If you gap on the high end the valves open later/close later this produces middle to high end torque plus more rpm slight but noticeable. Where can you use this, drag racing, roundy rounders anyting that involves power on the upper end.

Our elustrious cdi produces more torque on the bottom end so you know where I like to gap my valves. This is something I have found out by tinkering so I thought I would pass this on. If any of you try playing with valve gaps let me know how you make out I would be interested in your results.

 

Alltoys: With your new low comp. slugs you probably have lotsa room for more lift.That would help take advantage of the intake charge outa that blower.More than likely you could get away with quite a bit more duration as well.Time for a new set of cams,I'd say.(While your in there fixin the timing chains anyhow)Just stay away from too much overlap or you will bleed off valuble nitrous and boost.Im a huge nitrous junkie,but Ive never used it on anything smaller than a 302 Ford.Im gonna be up in your area somewhere tomorrow night and Wed,not too sure exactly where but the Edm area someplace(Im a truck driver).

 

650Mountain,
I do have a new set of cams already installed called a stage 2 these have a longer duration like you speek of they work excellent with the little extras.

 

That should be "open sooner/ close LATER", that will increase the TOP END power. Tight valve lash is good for slight increases in higher RPM power.

Also "open later/close SOONER", with loose/more open valve lash. This will give you a slight low RPM increase in power.

The theory is used in aftermarket hydraulic valve lifters of the variable duration type, such as the Rhoad's lifter. They pump down at an idle and at low RPM's to the point that the valve train gets noisy. This lowers the duration and increases bottom end power. As the RPM's build, the lifters "pump up" and take out the play (or excess gap) in the valve train and increases the duration that the valves are open. This increases high RPM power.

 

NovaKaw650,
Sounds good to me, you should try the gap on the cams with the modulator it will open some new avenues for you!!

 

Alltoys - now that you have the blower working, you should cut some new keyways in the cam sprockets so you can advance or retard the cam timing slightly. There are gains to be made with this; with the added boost the valve timing needs to be changed to optimize your output. I think the timing needs to be retarded with a blower; if you know someone that builds blown drag racing engines, they would know for sure. There's probably good blower equipped engine info on the web too. Some companies build blowers for Harleys, (I think), they should have the lowdown on valve timing changes.