On a 95" 10.8CR Road King, Would putting 1.7 rockers on the intake side of this cam to help boost the torque in the lower RPM's? All the dyno sheets that I look at show the cam coming in around 3K, I was wondering if it is possible to get it to come in around 2400-2600.

 

What about advancing it 4° too?

Yes, 1.7 rockers will have the effect of lowering power production in theory, not sure how much real world effect (I'm going a similar route in my current build and interested in this discussion). All I read said if you buy a complete set, you may as well use all four. The 'intake only' thing seemed to just be an economic thing from the old days/auto world.

You've already got 0.585 of lift with the 585, so doing the math you're going over .61.

You'd want rollers. I picked a set of Crane Cams 1.725s.

What 's the symptom you're unhappy with? Gearing is always another cheaper/easier way to crack the nut.

 

Going to 1.7s will increase the intake duration by 3-4 degrees. Results in a later intake close of 1.5 to 2 degrees.. Doubt you pick up anything except power up top.. 585s tend to over exhaust so the low end can fall off rather quickly.. You can change to the pipe to improve low end torque to some extent but you may also want to change the cam. Advancing the cam could help (as stated) but at 10.8 to 1 with a 41 degree intake close is pretty aggressive.. I run a Crane H290 at 42 intake close with 10.8 to 1 cr in a RK and the CCP is about 220 psi.

 

I just ran the numbers on the BB calculator with your H290 cam and it says you should be right around 207 psi. Is that calculator that far off? Now I'm 2nd guessing if I should be trusting putting my numbers in trying to stay around 195-200 CCP. With heads flowing as good as we have (275/216 @ 28) and 1.9/1.615 valves what would be a good cam for this 95" build? He'd like for the low end to start somewhere around 2500-2700 RPM's and run out to 120 MPH. The problem is, He is weight challenged and on a heavy bike. I thought about the TW8 but everyone says how noisy they are.

 

What is your current CCP? Just curious if the 10.8 CR is a measured and accurate number or a calculated number. Don't know how much lift your springs can handle but TMan 662-2 might work as bolt in with no rocker replacement but you should run rollers at that lift.

As for the BigBoyz calculator, I have almost always seen a variance, not huge but still a variance, between actual and calculated CCP. I haven't built that many motors, a few, but have not had one yet be dead nuts on with the BB number.

 

Well. IIRC it was 215 on cylinder and 220 on the other.. The compression gauge is an 1970 Snap-On I'd expect it to read a little higher.. Not to concerned about the final number +- 5% is fine with me.. H290 is a noisy cam but not like the W8 it replaced.. As far as cams go I'd use the Tman 590.. They whack 12 deg of the exhaust and only close one degree earlier than the 585.. 0.005 more lift..

Not sure who flowed the heads as they seem a little high for a 1.9 valve but that could be just the way it was tested.. I wouldn't have any problem running them but would fer sure add a throttle body at that flows.. Stocker will hold it back.

 

An S&S 585 with 1.7s on the intake only is a R&R 615. Look into some builds with those.

 

youde be better off advancing the cams 4* for moving the power to the left,1.7 rockers wont do that

 

Right on.
The rockers will not pull the power over to the left.
The 4* will push up the ccp a tick and historically move peak torque to the left about 200 rpms or so, with most cams.
Scott

 

I've tried to figure how you are getting a 220 ccp with an intake closing of 42*. at Best all I can calculate is 207. Can you or someone please explain how your getting that? Also if someone could explain the duration increase. I only understand it as lift increase. How can it change the opening and closing degrees?....Thanx.....