gear drive questions
Intermediate
Joined: May 2012
Posts: 31
Likes: 0
From: SoCal
I recently went with the full S&S setup in mine. Gear drive kit with 510 cams. I'm very happy with the setup. I mean i'm not reinventing the wheel here. Trusted name + proven combination = reliable results.
There is always that debate of whether you want the lower RPM cam or the higher RPM cam. Personally there is only 1 answer here for me, the higher RPM cam is the only thing that made any sense. While you may spend the majority of your riding time in the lower rpm range, that time is typically spent at a cruising speed where acceleration response isn't measured in the equation at all. When you are accelerating you're going to push into the higher RPM range, when you shift you stay there, and if in doing so your cam dies out at 5000 RPM you've now effectively lowered your rev limit. Unless you are drag racing or doing a bunch of light to light riding why would you ever desire to have the bulk of your power at the low end?
And it's not even as if the high RPM cam doesn't make more power at the low end anyway. I recently had the S&S 510 installed in my 88" '05 FXDWG, the cam is a 3000-5500rpm rated cam but there is a noticeable power increase in the lower range as well. You know they make these things called transmissions that allow you to downshift into a lower gear, thus increasing the RPM, should you absolutely need to get into the strongest pulling RPM range of your bike immediately.
So what is the big hoopla about needing some radical amount of power at the bottom that makes it worth it to lose so much top end?
There is always that debate of whether you want the lower RPM cam or the higher RPM cam. Personally there is only 1 answer here for me, the higher RPM cam is the only thing that made any sense. While you may spend the majority of your riding time in the lower rpm range, that time is typically spent at a cruising speed where acceleration response isn't measured in the equation at all. When you are accelerating you're going to push into the higher RPM range, when you shift you stay there, and if in doing so your cam dies out at 5000 RPM you've now effectively lowered your rev limit. Unless you are drag racing or doing a bunch of light to light riding why would you ever desire to have the bulk of your power at the low end?
And it's not even as if the high RPM cam doesn't make more power at the low end anyway. I recently had the S&S 510 installed in my 88" '05 FXDWG, the cam is a 3000-5500rpm rated cam but there is a noticeable power increase in the lower range as well. You know they make these things called transmissions that allow you to downshift into a lower gear, thus increasing the RPM, should you absolutely need to get into the strongest pulling RPM range of your bike immediately.
So what is the big hoopla about needing some radical amount of power at the bottom that makes it worth it to lose so much top end?
Outstanding HDF Member
Joined: Aug 2009
Posts: 2,938
Likes: 4
From: NC
S&S 510 Geardrives here.....I dont see the need in anything bigger than this unless you are gettin porting work done and even then I like a smaller cam for street use.
My stock 88 incher with a T Header, Open Air Filter, and 510 cams has nice torque but revs very quickly and doesnt fall off on top. I think they are a great street cam set for real world miles. No sense in clapping out the valvetrain by using oversized cams if they arent actually needed.
Plenty of guys makin over 100 HP/100 TQ on 510 cams with 95 inch kits. Thats plenty respectable for a engine build that merely requires cams,pipe, air filter, and a piston kit with some carb mods.
My stock 88 incher with a T Header, Open Air Filter, and 510 cams has nice torque but revs very quickly and doesnt fall off on top. I think they are a great street cam set for real world miles. No sense in clapping out the valvetrain by using oversized cams if they arent actually needed.
Plenty of guys makin over 100 HP/100 TQ on 510 cams with 95 inch kits. Thats plenty respectable for a engine build that merely requires cams,pipe, air filter, and a piston kit with some carb mods.
Club Member
Joined: Feb 2008
Posts: 11,483
Likes: 39
From: Passaic County, NJ
i put S&S cams in mine and a friends 88ci. Unless you take the heads off, you will need adjustable pushrods. If you are doing it yourself, you will need a puller to take out the inner cam bearings. I took the cam plate, outer cams and bearing to a dealer and had them remove the old cams, and install the new cams in the cam plate or you will need a hyd press and more tools.
Not sure which cam profile you are looking at, but the S&S I used where the 610s. Beside the cam kit, you will need the gear drive kit as well.
Not sure which cam profile you are looking at, but the S&S I used where the 610s. Beside the cam kit, you will need the gear drive kit as well.
You don't need to remove the whole head, just the rocker covers and rockers to gain access to the pushrods
Novice
Joined: Feb 2011
Posts: 17
Likes: 0
From: MN
I like the Wood cams but, I know a guy in town that has S&S cams that are .635 lift in his 95" and really likes them. Granted he has quite a bit of headwork done. Here is a sample graph from Wood's site. 585s vs TW-8.
http://www.woodcarbs.com/images/tc95tw8gvsSS585G.jpg
http://www.woodcarbs.com/images/tc95tw8gvsSS585G.jpg
Yeah, they are not intended for higher compression, and I'm guessing yours is a bit higher since you have a bore and aftermarket heads.
Elite HDF Member
Joined: Apr 2007
Posts: 4,919
Likes: 23
From: Seattle, WA
It would be really helpful for you to know what SE heads are on your bike ... if you look closely, you will probably be able to find the part number ...
Some SE heads increase the compression ratio (for example, the Kompressor heads and the MCR heads) ... if you don't have compression releases, you most likely don't have the latter ...
You could take a look at the Big Boyz calculator to approximate (pretty closely) what your compression ratio (and cylinder pressure in PSI) is / should be ... I am guessing around 9.2:1 and around 170 PSI ...
If you haven't experienced any issues with it starting, you probably don't need compression releases or a set of S&S easy start cams (with built-in compression releases) ...
The other bit of information (that knowing what heads you have) that could come in handy is how high of lift you can use ... for example, 0.635" is pretty high and a lot of heads (valve springs, technically) will not accomodate such cams ... also, if you know what the flow rates are at the various valve opening/lift you will better know how to optimize your cam selection ...
You will notice from the table above that some heads (this is true of non-Screamin' Eagle, too, by the way) do not significantly improve flow rates above 0.50" - 0.55" ...
Search for as much hard data as possible ... everyone seems to have an opinion ... but, the facts do not support everyone equally ...
Good luck with your decision ...
R/
'Chop
Some SE heads increase the compression ratio (for example, the Kompressor heads and the MCR heads) ... if you don't have compression releases, you most likely don't have the latter ...
You could take a look at the Big Boyz calculator to approximate (pretty closely) what your compression ratio (and cylinder pressure in PSI) is / should be ... I am guessing around 9.2:1 and around 170 PSI ...
If you haven't experienced any issues with it starting, you probably don't need compression releases or a set of S&S easy start cams (with built-in compression releases) ...
The other bit of information (that knowing what heads you have) that could come in handy is how high of lift you can use ... for example, 0.635" is pretty high and a lot of heads (valve springs, technically) will not accomodate such cams ... also, if you know what the flow rates are at the various valve opening/lift you will better know how to optimize your cam selection ...
You will notice from the table above that some heads (this is true of non-Screamin' Eagle, too, by the way) do not significantly improve flow rates above 0.50" - 0.55" ...
Search for as much hard data as possible ... everyone seems to have an opinion ... but, the facts do not support everyone equally ...
Good luck with your decision ...
R/
'Chop
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Thread Starter
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Tourer
Joined: Aug 2011
Posts: 321
Likes: 0
From: so fl
I'm pretty sure I just have the regular screaming eagle heads which only allow a lift of .580 max. I was looking at the s&s 570 but that makes them and the 583 out because they both lift higher. I do have compression releases and I definitely need them.
Last edited by jslum; Jun 16, 2012 at 04:00 PM. Reason: add to post
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