SE "E" Cams and SE .536 Cams

 

For many years now, HD has offered a popular set of XL performance cams commonly referred to as SE 536's (because they have .536" of lift). It's been a popular grind because it's capable of making good power and they're reasonably easy and inexpensive to install. Although they need better than stock springs and a check of piston-to-valve & valve-to-valve clearance, unlike a lot of larger grinds they don't need aftermarket lifters, adjustable pushrods & collapsible covers, or roller rockers, and that holds the costs way down. Also they're not so large that cam box or tappet pin clearancing is usually needed.

 

Shortly after the rubber mount Sportster was introduced for the '04 model year, HD started offering a new grind targeted at the new bikes. This new cam set (NRHS part number 66-2519704) is known as the "E" grind and is the same profile found in all Buell XB models, except with a rotor cup keyway and alignment marks set up for the XL cam box. They're specified as "bolt-in" for the '04 and later models, but can easily be fitted to any 91-03 as well with a change of springs.

 

The "E" grind is intriguing because it offers a little more lift than the SE536, .551" vs..536". They also have less duration. On the intake side, they open about the same place, but close 6 degrees sooner at 44 degrees ABDC vs. 50 degrees for the 536's. On the exhaust side they're advanced 4 degrees on the open point and a full 20 degrees on the close point. The latter really helps with the exhaust TDC lift, which has always been something of an issue when installing 536's.

 

So on paper, it's a grind that's narrower and taller, with earlier timing to make power a little lower in the rev range. The math and the simulation programs all say to expect more bottom end and mid range with a little less on top.

 

Well, I ran a set in my personal S2 Buell for awhile, and then I swapped'em out for a set of SE 536's with no other changes. And I always believe the dyno more than the math:

 

 

Being an S2, this Buell has a regular Sportster motor, not a Buell specific motor. Same heavy flywheels. I've swapped out the stock hemi chamber heads for a set of Stage 2 '04 XL1200 heads, and fitted a decent exhaust (Buell race kit). CR is 10:1 and it still had it's CV40 carb at this time. So it's representative a typical mildly modified XL motor.

 

So as predicted, the 536's pulled away on top. But contrary to the science, we got an absolute tie through the bottom end and mid range. This is even with heads that flow very well at high lift, which should give the additional lift and earlier timing of the "E" cams an advantage down there. But it's not to be found, the dyno doesn't lie.

 

Something the sheet doesn't show is that the valvetrain is noticeably quieter with the SE .536's. The "E" cams are getting a well deserved reputation for creating a lot of valvetrain clatter, which was actually my main motivation for swapping them out. Getting more power on top with no loss anywhere else was icing on the cake.

 

Both of these cam sets and many others are available from NRHS. See our camshafts page.

 

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