Big bore or cam?
Advanced
Joined: Mar 2007
Posts: 79
Likes: 0
From: Long Island NY
RE: Big bore or cam?
I see a lot of people talking of the Andrews 26 or 37, I am having the HCC Big Bore 95 kit with the 10.5 cyclingders .5 thousands ouver had the cylindrs honed to be true put in a 03 Ultra and selected the Andrew 31 with the gear drive as it came on a little earlier and seem to go almost out to 5800 which seem like the ideal cam for bagger. Warning to all who have a Twin cam with stock cams and milage above 25000 I would serious think abouth having them looked at, mine with 28000 were toast would not have made more than a coulple more thousand before they blew up in my opion from looking at the tensions are just about wore out completely.
Plan on using the PC III USB, how soon after you get this togeather should it be dyno.
thanks
Plan on using the PC III USB, how soon after you get this togeather should it be dyno.
thanks
Road Warrior
Joined: Jul 2006
Posts: 1,532
Likes: 7
From: Rochester N.Y.
RE: Big bore or cam?
Grinner , to keep a cam in the range you want , you would look at the specs at the site and choose your needs based on that.
Andrews shows these
21HG 1700-4800 RPM's
26HG 1800-5200 RPM's
37HG 2200-5600 RPM's
Your riding selection would show as the 21HG cam as the cam of choice.
If you run a stock compression ratio and valves and unported heads , you would want to increase low speed volumetric efficiency to improve your performance.
This would show a torque boost at lower RPM's with a milder cam.
As you go upward in cam selection , the volumetric efficiency goes upward in the RPM range , increasing horsepower and decreasing torque somewhat.
You can make up for the loss of low speed torque by upping compression later.
Kern , The bigger cams do make more power up higher , but at a loss of low RPM efficiency.
The way to gain low end power is to go with the highest lift/lowest duration cam you can find (with stock compression).
The bigger cams increase duration and overlap , thus dropping the "effective compression ratio" that you have down low.
This means the compression you already have would be used less effectively at the lower RPM's
The gear drive idea would kill 2 birds with one stone on these bikes as you wouldn't have the tensioners to mess with anymore.
I would think moneywise , the cam labor would be less than cylinders anyway , although you could do them later.
Hope this cleared up cam selection a little for some.
Mick
(Been a Mechanic for 30 years)
Andrews shows these
21HG 1700-4800 RPM's
26HG 1800-5200 RPM's
37HG 2200-5600 RPM's
Your riding selection would show as the 21HG cam as the cam of choice.
If you run a stock compression ratio and valves and unported heads , you would want to increase low speed volumetric efficiency to improve your performance.
This would show a torque boost at lower RPM's with a milder cam.
As you go upward in cam selection , the volumetric efficiency goes upward in the RPM range , increasing horsepower and decreasing torque somewhat.
You can make up for the loss of low speed torque by upping compression later.
Kern , The bigger cams do make more power up higher , but at a loss of low RPM efficiency.
The way to gain low end power is to go with the highest lift/lowest duration cam you can find (with stock compression).
The bigger cams increase duration and overlap , thus dropping the "effective compression ratio" that you have down low.
This means the compression you already have would be used less effectively at the lower RPM's
The gear drive idea would kill 2 birds with one stone on these bikes as you wouldn't have the tensioners to mess with anymore.
I would think moneywise , the cam labor would be less than cylinders anyway , although you could do them later.
Hope this cleared up cam selection a little for some.
Mick
(Been a Mechanic for 30 years)
Intermediate
Joined: May 2006
Posts: 25
Likes: 0
From: Santa Clarita, CA
RE: Big bore or cam?
Gentlemen, excellent discussion. As you can see from Mick's repsonse, the answers are evident. There is a guy, Joe Minton, who writes for American Rider Mag, published every other month. Minton is a Harley guru. Amongst his many achievements over nearly 40 years of H-D involvement, he wrote the Mikuni carb handbook. He has written many articles focusing on where to get the most useable power. This one article in particular answers this issue.
http://www.americanrider.com/output.cfm?id=1054045.
For some reason I can't get it to link.. Someone help me with this one please. Anyhow, he answers the hop up issue well for this inquiry. He is currently writing a series of articles concerning the best way to improve the 96 incher as well as the increase to 103". Thanks for all the input. I'm reading the forum info all the time. I guess I'll have to get som epphotos of my 96 Road King punched otu to 95" with the Sputhe kit. When all said and done, it puts out about 85 hp and 105 ft lbs of torque. Great bike but getting old like me and wearing out. The Road Glide is tempting.
wldegl
http://www.americanrider.com/output.cfm?id=1054045.
For some reason I can't get it to link.. Someone help me with this one please. Anyhow, he answers the hop up issue well for this inquiry. He is currently writing a series of articles concerning the best way to improve the 96 incher as well as the increase to 103". Thanks for all the input. I'm reading the forum info all the time. I guess I'll have to get som epphotos of my 96 Road King punched otu to 95" with the Sputhe kit. When all said and done, it puts out about 85 hp and 105 ft lbs of torque. Great bike but getting old like me and wearing out. The Road Glide is tempting.
wldegl
Grand HDF Member
Joined: Feb 2005
Posts: 4,307
Likes: 9,428
From: Twin Cities Minnesota
RE: Big bore or cam?
The Andrews 37 is not a good choice of cam for a bagger. I have been there and done that.....They are prone to "pinging" aka "detonation". You can tune it out at the cost of power. For the power range you are looking at go with the Andrews 26G, gear drive cams.
Road Master
Joined: Feb 2007
Posts: 1,025
Likes: 2
From:
Cruiser
Joined: Mar 2007
Posts: 228
Likes: 0
From: i live outside Omaha Ne on the Iowa side in the Loes hills, some great places to ride
RE: Big bore or cam?
it looks like we have some andrews sales people in this fourm.
there are a vast variety of cams. it is alot of money and a big step to create an engine you wish to have in the end.
i would suggest calling and talking to several places.
Head Quarters, Woods, Andrews, and maybe even a good harley dealer on the Screaming Eagle cams
i would actually say for the money and what you are wanting the Woods cams line would be your best investment.
duration is a good sign of torque. the longer the duration the longer the valves are open and your motor is not biulding compression. the shorter the duration the less the cam will preform at top RPM because there is less time at high RPM's to get burnt gases out and clean air in.
the Andrews cam is low lift and allows less air in at top lift.
stock cam has 216 intake and 220 exhaust and .473 lift
the 26G has 226 intake 230 exhaust and .495 lift
the 37G has 234 intake and 240 exhaust duration and .510 lift
the woods 234 intake 234 exhaust and .575 lift
this cam has alot of lift to let air in and out when the valves are open the other two don't gain much in lift over the stock cam.
a high end racer cam just to have a comparison would be a
Screaming Eagle cam 260
intake 263 exhaust 269 and .609 lift
woods version would be
268 intake and 268 exhaust with .678 lift
i hope this does not confuse you
but call other people to confirm what i have said.
and even give woods a call or look on their web site
www.woodcarbs.com
or call Bob Woods himslef at 205-525-4949
also along with the other post's on here, you need to have good fuel managment. and a good tuner (dyno operator)
sincerly
there are a vast variety of cams. it is alot of money and a big step to create an engine you wish to have in the end.
i would suggest calling and talking to several places.
Head Quarters, Woods, Andrews, and maybe even a good harley dealer on the Screaming Eagle cams
i would actually say for the money and what you are wanting the Woods cams line would be your best investment.
duration is a good sign of torque. the longer the duration the longer the valves are open and your motor is not biulding compression. the shorter the duration the less the cam will preform at top RPM because there is less time at high RPM's to get burnt gases out and clean air in.
the Andrews cam is low lift and allows less air in at top lift.
stock cam has 216 intake and 220 exhaust and .473 lift
the 26G has 226 intake 230 exhaust and .495 lift
the 37G has 234 intake and 240 exhaust duration and .510 lift
the woods 234 intake 234 exhaust and .575 lift
this cam has alot of lift to let air in and out when the valves are open the other two don't gain much in lift over the stock cam.
a high end racer cam just to have a comparison would be a
Screaming Eagle cam 260
intake 263 exhaust 269 and .609 lift
woods version would be
268 intake and 268 exhaust with .678 lift
i hope this does not confuse you
but call other people to confirm what i have said.
and even give woods a call or look on their web site
www.woodcarbs.com
or call Bob Woods himslef at 205-525-4949
also along with the other post's on here, you need to have good fuel managment. and a good tuner (dyno operator)
sincerly
Road Master
Joined: Jun 2006
Posts: 980
Likes: 1
From: The Grassy Knoll
RE: Big bore or cam?
Some very good info TG. Just went through the Woods site, good stuff on there.
Will definitely be doing some intensive "research" before I drop any more money on my chrome crackpipe.
Thank you muchfor the informative post.
Will definitely be doing some intensive "research" before I drop any more money on my chrome crackpipe.
Thank you muchfor the informative post.
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Intermediate
Joined: May 2006
Posts: 25
Likes: 0
From: Santa Clarita, CA
RE: Big bore or cam?
That is one of the many articles Joe has written and is on point, but not the one I am referring to. If you Google Joe Minton the article will be located. Worth reading as he has tested just about every combo out there and for the mid range power curve he knows what he is talking about.
Road Master
Joined: Jul 2005
Posts: 840
Likes: 0
From: elkton, va
RE: Big bore or cam?
ORIGINAL: wldegl
This one article in particular answers this issue.
http://www.americanrider.com/output.cfm?id=1054045.
For some reason I can't get it to link.. Someone help me with this one please.
wldegl
This one article in particular answers this issue.
http://www.americanrider.com/output.cfm?id=1054045.
For some reason I can't get it to link.. Someone help me with this one please.
wldegl
It would link because you had a period included at the end of the URL. Try it here:
http://www.americanrider.com/output.cfm?id=1054045
L8r