REPRINT FROM OLD HTT: Cam Basics For Harley Davidson Motorcycles

[ClassicRider2002]

DISCLAIMER: THIS IS A REPRINT TOPIC FROM "OLD" HTT

I have saved many great topical discussions as "links" over the years and would hate to see these lost, so I am reprinting this TOPIC here, which may "perhaps" help some.

TOPIC:  Cam Basics For Harley Davidson Motorcycles  02-13-06

   

From: Jiggyfingers  (Original Message) Sent: 2/13/2006 6:55 PM   Message 1 of 14 in Discussion

THIS THREAD HAD THE FOLLOWING LINK TYPED IN BELOW FOR READERS TO GO TO, HOWEVER IT SEEMS NOT TO BE A WORKING "LINK" NOW, HOWEVER THE REST OF THE THREAD IS INTERESTING:

http://www.directparts.com/static/articles/cambasics_harley.htm

[ClassicRider2002]

 

From: ClassicRider2002 Sent: 2/14/2006 12:19 AM   Message 2 of 14 in Discussion
Jiggyfingers....

Wonderful reading.....I have done some copying and pasting from the site....and have included a cam I would like to know about as far as what this article is trying to say.....about when to expect a cam to "turn on"

Can anyone interpret the results for me PLEASE?

Cam timing: what matters

The most important cam timing event is the intake valve closing angle. The intake closing point determines the minimum rpm at which the engine begins to do its best work. The later the intake valves close, the higher the rpm must be before the engine gets "on the cam."

Long duration, late closing cam designs are necessary to drag the last bit of power out of an engine. Unfortunately, these same cams can perform poorly under more normal riding conditions. In the quest for maximum power output, many-too-many Harley owners choose a late closing, high-rpm cam for their engine. The problem with such choices is that the engine seldom spends time in the rpm range favored by such cams.

The majority of virtually any Harley motor's life is spent in the mid-portion of its rpm limits, between 2000 and 4000 rpm. At open-road cruising speeds, that range is more like 2500 to 3500 rpm. With current Big Twin gearing, top gear at 2500 rpm returns a road speed of 55 mph and 3500 delivers 84 mph. Riders sometimes "putt" around at 2000 or less. Even when accelerating to cruising speed, few of us use more than 4000 - 4500 rpm as a shift point. Very seldom, in day-to-day use, do our engines get near 5000 rpm, let alone 6000.

Even the mildest of Harley-Davidson's aftermarket cams (Evo or Twin Cam) do their best work above 3000 rpm. At 2000, the majority of these cams seldom perform significantly better than stock cam(s).

The rpm at which a Big Twin gets "happy" can be predicted by the closing point (angle) of the intake valves. The angle is expressed as the number of degrees After Bottom Dead Center (ABDC) that the valves reach .053" from being fully seated.

The following list predicts the rpm at which the engine gets "on the cam" based on the closing angle of the intake valves. These relationships are approximate but should hold true to within 200 rpm or so. They also assume that all other tuning factors, exhaust, ignition, etc., are operating correctly.


30 degrees = 2400 rpm
35 degrees = 3000 rpm
40 degrees = 3600 rpm
45 degrees = 4000 rpm
50+ degrees = 4500 rpm

If you have one of the late closing cam designs installed, say one that closes the intake valves later than 40 degrees, then you cannot expect excellent performance at 2000 rpm. No carburetor adjustment, ignition adjustment or exhaust system can change this.

Ok so with all of the above information can someone interpret the data well enough to tell me about the characteristics of this cam?

Here is the breakdown of the cam:

V~Thunder 3010 cam   
         
Gross Valve Lift                     In  .500    Ex  .500
Lobe Lift                                  In  .3125  Ex  .3125
Duration @ .053"                   In   234    Ex   234
Valve Timing Open/Close    In  15/39  Ex  39/15
Lobe Center Line                   In   102    Ex   102
Lobe Seperation                              102
Base Circle Radius                         .530"
Tappet Lift @ TDC                 In  .096"   Ex  .096"
Valve @ TDc                           In  .154"   Ex  .154"

Do you have enough information here to tell me when this cam will turn on based upon "Direct Parts" tech information from above....as well as the tech info for the V~Thunder 3010 cam??

I am really curious about when this cam will begin to "get on" in other words...direct parts talks about the "closing angle of the intake valves" thus what is the closing angle of the V~3010 cam...I know the numbers are above but I am not interpreting them well here....

Thanks everyone....perhaps this is obvious to most everyone....but my glasses are a bit "blurry" at this point....and I need some help to understand....I see the numbers but I am not sure how to interpret them....

Regards,

"Classic"

From: martida01 Sent: 2/14/2006 5:53 AM   Message 3 of 14 in Discussion    
Someone posted a while back.  Enough info to make your head spin. 

CAM TIMING:

http://www.hartwellmotorcycles.com/cams.html
http://www.nrhsperformance.com/tech_camshafts.shtml
http://users.spec.net/home/emxjc/cam_shaft_power.html
http://e30m3performance.com/myths/more_myths1/comp_ratio/comp_ratio2.htm
http://www.compcams.com/information/tutorials/
http://www.hotrod.com/techarticles/50983/
http://www.nightrider.com/biketech/camterms.htm
http://www.aperaceparts.com/tech/camterminology.html
http://www.lowridermagazine.com/tech/0409lrm_camtech/
http://clubs.hemmings.com/clubsites/MTFCTulsa/cams/cambasics.htm
http://www.sverrekahrsracing.no/Butikk/compcams/Ventiltiming/ventiltiming.htm
   

From: ClassicRider2002 Sent: 2/14/2006 10:33 AM   Message 4 of 14 in Discussion
Thank you martida01 for all of that information!!!!!!

I am still curious about my above question whether anyone can assist me with the answer of the specific cam and how to interpret when the cam, that I mentioned above, will turn on?

I copy and pasted from the websites listed above and ended up with about 23 pages of notes....great for future reference and you right my head is currently spinning....

However, I am left with my "simple" (yeah right, simple?) question above....can anyone answer the question in context to the discussion that resulted from reading the copy and pasted information I included/posted above which created the question of when will the V~Thunder 3010 cam turn on?

As I said I appreciate the information that was reposted....and will be put in my library of notes.....ultimately within those notes perhaps my answer already exists but as was mentioned my head is spinning and I am not sure I have the cognitive ability to surmize an answer just yet with any confidence........thus, I would like to know if any of you can assist me here with when this cam will turn on from a technical standpoint besides say....seat of the pants feel.....if that makes sense...by the way we are talking about an otherwise stock evo engine inclusive with a vance and hines 2 into 1 pro pipe for the exhaust and a fairly simple rejetting of the carb.....

Regards,

"Classic"
 

From: Jiggyfingers Sent: 2/14/2006 10:55 AM   Message 5 of 14 in Discussion
Sounds like we need Big John Rosemond to save the day.


From: heritagespecial Sent: 2/14/2006 11:47 AM   Message 6 of 14 in Discussion
Well, hope this helps--the way I read it based on the info you provided is:

V thunder 3010
Valve Timing Open/Close    Intake  15/39  Exhaust  39/15
The rpm at which a Big Twin gets "happy" can be predicted by the closing point (angle) of the intake valves.

Therefore the intake valve closes at 39 degrees. So if the info provided is good info, then the suggested cam comes on at 3900 rpm based on the following:
(40 degrees = 3600 rpm from the info in the mail above.)

Regards,
HS


From: electricrigidshovel Sent: 2/14/2006 1:13 PM   Message 7 of 14 in Discussion
That cam is in it's sweet spot about 3500 rpm, predictable from the tables above. It has also been pulling well since around 2500 and will start to slump a little around 4700 or so in comparison to cams with increased timing events. It is a pretty mild cam, but would be good for heavy bikes. That's my take on it. Surely there are folks with first hand experience.


From: JAMESP1232 Sent: 2/14/2006 1:27 PM   Message 8 of 14 in Discussion
Classic, 30 degree or less overlap produces the best low end power. The closing point of the intake valve will determine where the cylinder actually begins to build pressure.Overlap is the area around Top Dead Center where both valve are open.
Ramp design can have an effect of when the motor is "on the cam" so it is not a cut and dried relationship as the info suggests.
V Thunder talks about making power "under the curve"
The V thunder website has some interesting info and I talked to a tech guy there yesterday and he was helpful...Time to leave work and go home,,,,,


From: ClassicRider2002 Sent: 2/14/2006 4:16 PM   Message 9 of 14 in Discussion
electricrigidshovel~

That cam is in it's sweet spot about 3500 rpm, predictable from the tables above. It has also been pulling well since around 2500 and will start to slump a little around 4700 or so in comparison to cams with increased timing events. It is a pretty mild cam, but would be good for heavy bikes. That's my take on it. Surely there are folks with first hand experience.

-----------------------------------------------------------------------------------
electricrigidshovel.....that's a mouthful...lol (teasing) say that without slurring your vowels.....lol....anyway....let's see here I do have first hand experience with the cam...."from seat of the pants" as it is in my 1999 FXR2.  I am not seeing the transition of the math here that has resulted in your conclusion to state that the cam's sweet spot is 3500 rpm.  I am reading what you are communicating don't get me wrong....but lost in the translation is how did you arrive at the 3500 rpm. 

If you read the first article above that "jiggy" referred us all to in this post, the truth is for my riding experience is that I am only getting power up to around 4400 to 4500 rpm for shifting purposes if I am actually getting on it....and going down the highway of course keeping it around 3100 to 3400 rpm. 

electricrigidshovel....but as you know you mentioned the cam would be "Good" for "heavy" bikes...the reality is the FXR2 is 611 lbs weight making it one of the lightest HD bikes. So what would this mean in relation to being a good cam for a "heavy" bike.

I am not trying to recreate the wheel....but perhaps trying to understand in actualality what this cam "technically" does....as for how it opens up and performs....

I suppose as some would say is it running well on your bike and do you like it....and yes to both of those but now I am curious as to the "technical" issues of it as I just mentioned.....

Thank you for your additional help!!!!
----------------------------------------------------------------------

JAMESP1232.....

thanks for your input....but it's still a bit of "greek" to me.....and what you introduced is a continuation of what the 23 pages of text I have that are in connection with what was first introduced by the websites above....I do appreciate your assistance and input....and I more or less follow what you are saying about having 30 degrees or less overlaping to produce the best low end power....so I am left with understanding what this cam is actually doing.....as electricrigidshovel said and also from what heritagespecial was saying (also thank you heritagespecial for your input as well)

If this cam is turning on at 3900 rpm that's a bit later than what I wanted it to.....it seems to turn on faster than that.....but perhaps that is only because in my mind I want it to.....perhaps now you are seeing my confusion and wanting to know what I really want it to do....

Ok so any other input....and perhaps it's all right in front of me within this post....and I am making this too difficult which by the way I am usually guilty of....any further clarification would be greatly appreciated.....

I am tryin to understand really....but I know if I can articulate it to another then I have a firm grasp and right now I feel like I have information but no clear understanding...

If John S reads this and you have some input....greatly appreciated too....(your right jiggyfingers, lol)

AND really THANK YOU TO ALL OF YOU...I know I know....after you scratch your head and tell me....."IT'S RIGHT THERE IN FRONT OF YOU, JUST READ" take a deep breath and try me again.....

Regards,

"Classic"

 
From: JAMESP1232 Sent: 2/14/2006 5:45 PM   Message 10 of 14 in Discussion   
Classic. I have used the 3010 cam in my bike since 2001. It is a good cam for heavy bikes AND light bikes as advertised. I went from stock cam to EV-27 to V Thunder 3020 to the 3010 and compared to the stock cam this thing is getting "on" the cam before 2000 rpm, now it isnt wringing max benefit at that rpm but it is very noticable. I am able to set my Daytona Twin Tech ignition .at maximum advance , most aggressive street mode and never ping.
The ramp design and timing events make some well designed cams create power under the curve as Comp Cams advertises The online catalog at their website explains how a cam should be degreed and has a couple of good paragraphs explaining valve timing.I really dont know anything about the "how" or "why" I just know I like what it does and now I want more of it.


From: Sledgehammer5651 Sent: 2/15/2006 5:52 AM   Message 11 of 14 in Discussion
Hi !

Dyno sheet 1989 FLHTC :
-Edelbrock Heads
-Edelbrock All new design carb 38 mm
-Amm-ign.
-Hard -Krome 2 into 1 Xccelerators
-EVL-3010
-Accel coil+ 8,8 mm wires
-Back wheel horses

1989 FLHTC.JPG   


From: JAMESP1232 Sent: 2/15/2006 6:31 AM   Message 12 of 14 in Discussion
Sledgehammer, so is this eq. to 89 ft/lbs of torque and ?  how much horsepower....What is hv?


From: Jiggyfingers Sent: 2/15/2006 8:18 AM   Message 13 of 14 in Discussion
http://motorcycleinfo.calsci.com/HP2.html

this article nicely explains what you are looking for.


From: TarheelFXR Sent: 2/15/2006 8:25 AM   Message 14 of 14 in Discussion   
Classic,

James is on the money, anything over about 30 to 32 degrees of overlap will drop your static compression more than stock heads and pistons like (so you will need higher compression than stock) and the longer duration of these cams will shift the performance up in the rpms.  Most all cams really only work over a 3,000 rpm to 3,500 rpm range (more or less) so it comes down to do you want low end grunt or high rev. HP?

I run a EVL3020, the next cam up from the 3010, in my FXR and I love it.  I'll post dyno later but it produces about 86 ft/lbs and about 75 hp with mik 42, pythons, crane hi4e and stock pistons and heads.  I think the 3010 is a great cam but as light as the FXR is, you can use the slightly more aggresive 3020. 

T

[ClassicRider2002]

Anything added beyond this point is new information.

Regards,

"Classic"