I've got a 107" S&S out of a Big Dog with a 520 cam in it... Considering installing a 585 cam to put it to S&S's standards... Is there a lot of difference there between the two cams (horsepower/torque)? Would like to know horsepower gains from switching to the 585..
Thanks,
Nate

 

yes there will be a big difference,but make sure you get the compression in the 10.5-1 to 10.8-1 range (with a .030 squish,the BD motors were notorious for have piston not come all the way to the top of the cylinder).the .520 is a EPA cam that works better with lower compression.the .520 also makes its power a lot earlier and peters out earlier than the 585.the 585 with the right compression will make very nice power from around 3300-6500+ (2000-4500 for the .520)

 

I believe I've got right around 9.5 to 1, maybe 9.6 to 1 comp ratio, Will that .030 squish raise it up enough, or does that require different pistons, maybe shave the head?
I still want to run pump gas though. And really not looking for "every" bit of power I can squeeze out of the engine, just be nice to have a little more...

 

piston can be .050 in the hole on some BD motors.i really don't remember if they had special pistons made or just ran longer cylinders (been a while since I messed with one)either way,your going to have to get back to a 0 deck hirght (either with pistons or just cutting the cylinders down),then cc the heads and go from there.you`ll want to use .030 gaskets with whatever you end up doing to get 0 deck height and figuring desired cc amount

 

[QUOTE=Chopper Nate;13588514]I've got a 107" S&S out of a Big Dog with a 520 cam in it... Considering installing a 585 cam to put it to S&S's standards... Is there a lot of difference there between the two cams (horsepower/torque)? Would like to know horsepower gains from switching to the 585..
Thanks,
Nate[/QUOTE

Back in the chopper-builder days, of Titan, AIH, Big Dog, Illusion, etc, a "go-to" combo here used was to perform cylinder head work, install a Thunderjet, adjustable ignition, and either a Wood 9B, or 9F cam.
Many times we'd use a 1" spacer between the carb and intake manifold, which is something most folks don't even think about thses days.(not us)
Most would come in the door with a Supertrapp, Pro-Pipe or Thunderheader.
They'd hover at 125/125, sae, and had a couple up near 130 hp, but if I recall, those had a White Bros, E Pipe on them.
That was almost 20 years ago.
Scott

 

I have a crate S&S V107T that has 9.5:1 CR with it's stock 585 cam. It gives just over 100/100 with a wide flat torque curve and is great to ride. As Kirby and Scott point out it can do even better with more CR and a touch of their magic dust, but if your engine has the same cam clearances as mine (made in 2008) a change of cam looks like a simple and cheap upgrade, for minimal effort. S&S also use the 585 in one of their 124" engines, so it is a versatile cam.

 

The cylinders were longer. As stated. cut them down to 0 deck height.

 

actually I did remember cutting them down after I posted,not a big deal

 

We've seen the 117" crate engines with the piston down in the hole on average .042-.044".
Recently upgraded one for a client that lives right here in town
Big Dog.
Used a Wood W-6HE.
Thunderheart adj. ignition
Thunderjetted the G carb and used the large S&S element.
Headwork
Sectioned the baffle on the V&H Big Radius pipes.
Went off at 124/136 sae at 10.5 cr.
Client was thrilled.
Scott