I'm not completely new to HDForums, but this is my first "New Post". I have an '05 Road glide that the original owner loved dearly and poured cash into, making what amounted to a great "down payment" for me and a screaming high speed cruiser. But, it doesn't make enough torque for me at lower engine speeds. I want to flatten the torque curve out and set it up to "come on" in the lower 2K range and run strong up through mid to high 4k or even into the low 5k's if possible. There seems to be a lot of pre-detonation in the engine around the 3k mark, and more than anything, I want to eliminate the detonation, and everything that goes with it.

The motor has been upgraded to 95" using H-D Screamin' Eagle kits and components, including the Stage II Big Bore Kit, Screamin' Eagle Pro Performance Heads, and SE257 cams, instead of the included SE 203 Cams. A Power commander manages fuel mapping changes. I "think" I'm running about a 10:1 ratio, based on the table in the catalog. I'm pretty sure I want to go with S&S Gear Drive cams, as long as the run-out on my crank is less than .003. With that all said, I've got a couple of questions:

With H-D Stage II 1550cc kit 29859-04, including the pistons that come with the kit, and Screamin' Eagle Pro Performance Cylinder Heads (p/n) 16953-99C, and no other modifications,I believe the compression ratio should be 10:1.

Can anyone confirm that value?

Will I see a major torque (and thereby rideability) improvement if I go with the 570G S&S cams? I've been pointed toward the S&S 570G cam set, as S&S recommends it with up to 10:1 compression. The heads support up to .575" valve lift, and the 570s come it at .570" (duh!) Reviewing the specs of this cam, there isn't a great difference between the duration of the SE257 (252intake/260exhaust) as compared to 240i and 255e, but S&S offers a 546G, with an honorable lift,(.546"), but greatly reduced duration (240i and 237e). The S&S web site doesn't detail what performance to expect with the 546G, so I'm coming to the forum, looking for advice, and experience with this setup.

Does anyone have experience with the 546G and 570G cams?

Thanks in advance!

Steve

 

I was steered away from the s&s 570G cams. I'm glad too! There are better cams out their for aboutthe same price. A good place to do some research would be, www.niterider.com They have alot of technical data for the guys and gals that want to think before they act. Andrews, Woods, and KuryakynWild things have some nice choices. Woods andKuryakyn are a little more pricey though. Go to the Cam websites, look at the dynos, emailand call the tech support guys.
I'm in the process of swithing from chains to gears inmy motor now.

 

Yes, you can do better than the S&S cams, Woods, or Head Quarters have grinds that will offer big toruque gains over what your running now.

You will need a different PC map, the one you have now may have too much timming.

 

That would be http://www.nightrider.com/biketech/.

 

For low and mid torque one thing to look for is, intakes closing at about 40 deg. Not much later, if any.

 

Bigboyzracing.com has a calculator to let you see what cams will do to compression. You'll need to do a compression check on your engine to know for sure what cam changes will do. If you only change your cams to a torque cam your compression will increase dramatically, and that could cause detonation issues.