actual cam RPMs...

[hattitude]

I am going to do a cam tensioner update for a friend's 2004 Twin Cam Softail.

While getting the parts together, I bought two Koyo B-148 (B-148;PB;L125) inner cam bearings.

I bought them off Amazon.com (too easy), then noticed on the add, it said:

"Koyo B-148 Needle Roller Bearing, Full compliment drawn cup, Open, Inch, 7/8"ID. 1-1/8" OD, 1/2" Width, 4800rpm Maximum Rotational Speed."

Always a little skeptical of Amazon purchases, as there are many stories of "substituted" items being passed off as originals...   I took note of the "4800rpm maximum rotational speed" I realize this could just be an inaccurate item description.... but...

I'm pretty sure with the gears and all, the cams don't turn the same rpms as the crank, but I realized I have no idea if they spin faster or slower...

Does anyone know the rpm range that the cams themselves spin in an 88" Twin Cam engine?

I just want to make sure the inner cam bearings I bought off Amazon are the correct ones...

[Hossamania]

The cam spins half as fast as the crank.
6000 rpm motor, 3000 rpm cam shaft

[hattitude]

The cam spins half as fast as the crank.
6000 rpm motor, 3000 rpm cam shaft

Awesome thanks....

I've never heard/thought/known about that bit of info...

 

[kd]

The cam spins half as fast as the crank.
6000 rpm motor, 3000 rpm cam shaft

Awesome thanks....

I've never heard/thought/known about that bit of info...

 

Look at it this way.  In a 4 stroke engine it takes 4 stokes per each power stroke.  There's one up and one down stroke in each 360  degree crank rotation. Say that's intake & compression then power and exhaust is another rotation with 2 strokes.(then start over). The cam shaft has one bump per valve lifter so it will have to rotate at half the speed of the crank to time it right to open or close a valve at the right time.

[Coyote]

 

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[kd]

    Much easier if you can see it.

[Ohio HD]

Easy to see the two to one ratio with gears.

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[hattitude]

Damn....

It seems so simple now....   

I appreciate the education...