"One thing that's needed to know about ratio rockers is that the effective duration between the .050" lift points is extended, and this will lower your working compression some. So be prepared to make a compression increase when using this package. With the Ace Magnum cams, the .050" duration is extended by about 24 degrees, with 12 of those degrees on the inlet closing side. That is probably going to drop the compression test psi by about 10 psi. You can reduce the thickness of your barrel base gasket stack, or you can use the 3-way timing pinion to advance the valve timing by 4.5 degrees, to help compensate the compression. Advancing the cams also changes the lobe center angles, and will affect power curve characteristics on a peakier way, and you need to watch out for valve/piston clash when doing that. A test during the build, of slowly rotating the engine by hand, with a thin(.060") layer of soft clay in the piston's valve reliefs is the usual testing protocol. " From Ace in his new parts thread
I have been thinking about my Fireball back in the states and I rebuilt it just as I had been running it at 4500' with not plate and just one cylinder base gasket. Now that I have my bike in Boston which is pretty much sea level I am wondering if I may end up with too much static compression. I copied Ace's write up above as it got me thinking that maybe if I end up with too much compression I can switch to the Shotgun 410's which by extending the valve timings a little might reduce my static compression so that I don't need to add an extra gasket or spacer. And get a performance boost as well.....I had been thinking of these rockers for after I get the engine broken in again but if I find when I get back to it that I am over compressing it this might be a good option....