Cam timing in general

[Harley Pilot]

So when choosing a "bolt in" cam if you're not choosing one with at least the same if not earlier IVC than stock how is it possible to make any gains in torque?

[Hossamania]

More lift?

[PoorUB]

 

Cam profile, faster opening and closing.

[Harley Pilot]

More lift?

Granted, up to the flo limits of the parts in place though correct?

[Harley Pilot]

Cam profile, faster opening and closing.

Again I agree,  so how much lift is needed to overcome a later IVC of say 10° for instance?? Just trying to have it make sense in my noggin

[DTTJGlide]

If you're bumping it up 10* you should bump the CR a little with at least a thinner HG or you're not going to have more left side  TQ. You can get higher overall TQ but it's going to be soft down low.

[Harley Pilot]

If you're bumping it up 10* you should bump the CR a little with at least a thinner HG or you're not going to have more left side  TQ. You can get higher overall TQ but it's going to be soft down low.

But that wouldnt be a " bolt in" cam to me any ways.

[FXDBI]

If you're bumping it up 10* you should bump the CR a little with at least a thinner HG or you're not going to have more left side  TQ. You can get higher overall TQ but it's going to be soft down low.

But that wouldnt be a " bolt in" cam to me any ways.

Bolt in Cam means just that it will bolt in using stock push rods because the base circle is the same, the springs can handle the lift, the case has room for the lobes to rotate and the valve protrusions at TDC wont hit the piston. They all need tuning to optimize the change in cam timing and opening. Hope that explains it better.   Bob

[1FSTRK]

Any cam timing changes that result in trapping more A/F mixture in the cylinder will make more torque. Simply closing the intake valve early will raise the corrected compression but moving all the valve timing events in unison can increase cylinder fill and if timed correctly trap even more A/F mixture.  Adjusting overlap with later intake closing while adding a less restrictive exhaust system and air cleaner can speed port velocity and result in more trapped mixture in the cylinder even at low rpm's. The advantage of this over simply using early IVC is the increases carry over a broader  rpm range.

[Harley Pilot]

Any cam timing changes that result in trapping more A/F mixture in the cylinder will make more torque. Simply closing the intake valve early will raise the corrected compression but moving all the valve timing events in unison can increase cylinder fill and if timed correctly trap even more A/F mixture.  Adjusting overlap with later intake closing while adding a less restrictive exhaust system and air cleaner can speed port velocity and result in more trapped mixture in the cylinder even at low rpm's. The advantage of this over simply using early IVC is the increases carry over a broader  rpm range.

If you're bumping it up 10* you should bump the CR a little with at least a thinner HG or you're not going to have more left side  TQ. You can get higher overall TQ but it's going to be soft down low.

But that wouldnt be a " bolt in" cam to me any ways.

Bolt in Cam means just that it will bolt in using stock push rods because the base circle is the same, the springs can handle the lift, the case has room for the lobes to rotate and the valve protrusions at TDC wont hit the piston. They all need tuning to optimize the change in cam timing and opening. Hope that explains it better.   Bob

Yes all the answers help, so bottom line is I've been on a search for a good cam for my Tri-Glide I have decide on the Andrews 48H but I have ran some cams in other motors with earlier closing(18°)  and had great results but with the Twin cooled already aproaching 10-1 static Im gonna give these a try. Im just trying to better understand all the things that seperate one from the other as to narrow lost revenue looking for a cam that will give me what I desire from my scooter.

Again ALL input is appreciated!

[KE5RBD]

The Andrews 48H is good choice in the Rushmore engines for good torque.  The Stock Rushmore Intake close is 30 and the 48H is 29.  The 48H is advanced on the intake timing 6 degrees over the Rushmore with the Rushmore having a Intake center of 104 and the 48H is 98.  This give better early torque for the 48H.  The Rushmore has 211 intake duration and the 48H is 222 intake duration.  The other thing is the Rushmore has .511" lift and the 48H has .548" The more duration and lift means it will pull to higher rpms than the Rushmore and should out do the Rushmore from 2000 up. The Rushmore is no weakling when tuned either.  All this being said the Rushmore and Andrews will benefit from a good tune as will any cam. An autotune won't likely get you what you want in low end torque with either cam.

[Harley Pilot]

The Andrews 48H is good choice in the Rushmore engines for good torque.  The Stock Rushmore Intake close is 30 and the 48H is 29.  The 48H is advanced on the intake timing 6 degrees over the Rushmore with the Rushmore having a Intake center of 104 and the 48H is 98.  This give better early torque for the 48H.  The Rushmore has 211 intake duration and the 48H is 222 intake duration.  The other thing is the Rushmore has .511" lift and the 48H has .548" The more duration and lift means it will pull to higher rpms than the Rushmore and should out do the Rushmore from 2000 up. The Rushmore is no weakling when tuned either.  All this being said the Rushmore and Andrews will benefit from a good tune as will any cam. An autotune won't likely get you what you want in low end torque with either cam.

I was truly impressed with the stock situation after switching to the basani head pipe and some Cobra 3/12" RPT slip ons, for being 400+ LBS heavier than a two wheeler it had decent power. That being said with highway speeds out west here I was wanting a wee bit more from the old girl w/o doing any extensive work. Im looking forward to the swap and the installation of the target tune module.