Forums
New posts
Search forums
What's new
New posts
New media
New media comments
Latest activity
Classifieds
Media
New media
New comments
Search media
Log in
Register
What's New?
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Navigation
Install the app
Install
More Options
Advertise with us
Contact Us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Hobbies & Interests
Gearheads
SBC Primer
Search titles only
By:
Reply to Thread
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="swampratt" data-source="post: 3102054" data-attributes="member: 15054"><p>Oh yes .050"</p><p>A camshaft is rated in Lobe Lift. and Duration and overlap and lobe separation angle and many other things. </p><p>Lift is how far the peak of the lobe is away from the radius of the base circle of the camshaft. Or you can say Lift is how much it will lift the valve open.</p><p>Lobe lift of say .300" will have the peak of the cam lobe .300" away from the radius of the base circle of the cam.</p><p>Say you have .300" lobe lift you also have a 1.5 :1 rocker arm ratio. it will multiply .300 x 1.5 =.450" there you have .450" of valve lift. valve is opened .450"</p><p>Now the .050" and duration.</p><p>Duration advertised on a camshaft can be advertised as 290 duration or say 268 duration.. now that can be misleading .</p><p>Because it is advertised and many times that advertised duration number could be at .006" valve lift or .012" valve lift.</p><p></p><p>Manufactures do not always tell at what Valve lift "advertised"duration is calculated at.</p><p></p><p>So a basic industry standard was set so we could compare a camshaft more easily and choose what we want.</p><p>SO the .050" spec was set forth.</p><p>Almost all cam manufactures will have the .050" spec for you too see in their advertisement.</p><p></p><p>so 260 duration at .050".. means 260 degrees duration of that cam beginning the measuring process after the lifter was lifted .050" and end the measuring process when the lifter or cam follower is .050" from closing.</p><p>So basically sliding up the lobe to start your measurement. now you can see advertised at 292 at .006 will be different than advertised 292 at .012" .</p><p></p><p>It does not get any better ...050" is not the end all in comparing cams or trying to pick one and how they will act.</p><p>You have duration at .200" lift also. you can have the same say 260 duration at .050" lift on 2 cams and at 200" lift one cam may have 138 duration and another will have 168 duration.. that 168 duration will make more power as it is holding the valves open much longer and allowing the cylinder to fill up with more air.</p><p></p><p>This may explain some of it better.</p><p><a href="http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx" target="_blank">http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx</a></p><p></p><p>There are exceptions to the rule when reading what cam manufacturers post about overlap and Lobe separation angle.</p><p></p><p>Most will state LSA Lobe separation angle if you make it wider say from 106 to 115 LSA the 115 LSA will have a more broad power curve and carry power farther past the peak HP rating.</p><p>Say peak HP is at 5700rpm.. they are saying the 115 LSA will not drop power off a rapidly past 5700 rpm as a 106 LSA cam will.</p><p></p><p>I found in my testing that is NOT true all the time. It has a lot to do with lobe events.. when the exhaust lobe is opened and closed and when the intake is opened and closed.</p><p></p><p>I have had Odd cams speced for my little 350's and just recently I had an odd ball made in search for more MPG it had a wider LSA 112 but power past the peak fell off like a brick compared to the narrow 106 LSA.</p><p></p><p>Both cams i compared in the same engine back to back both cams were ground with the same master lobe I just juggled the LSA .. but this experimental cam I only changed where the ex lobe would be.. left the intake lobe opening and closing rates the same between the 2 cams.</p><p></p><p>My theory was I would not loose my Low speed power because I had 225 PSI cranking pressure and intake valve closing determines what that will be ..I did not want that to change as with high cranking pressures comes brute power out of the hole.</p><p></p><p>Get the heavy vehicle moving.</p><p>Big juggling act.</p><p>That cam is what i am running now the 112LSA experimental in my 350.</p><p>MPG went from 12-14 to 17-18 MPG.</p><p>Peak HP was made at the same RPM on both cams 5700rpm but by 6500rpm the 112LSA was down over 40 HP.</p><p></p><p>Normally you do not get to 112 LSA by moving the ex lobe only you move both lobes.. in doing that the intake valve would close later in the cycle and add a little more power on the top.</p><p></p><p>Confused yet??</p><p>My cam grinder said I change cams like he changes underwear. <img src="/images/smilies/smile.png" class="smilie" loading="lazy" alt=":)" title="Smile :)" data-shortname=":)" /></p><p>I am always wanting to experiment.</p><p>I almost wanted to have another made but go to 117 LSA and see if i could pull 22+ MPG.. this is normal driving with some spirited tossed in. not hypermiling. NO OD no FI and not a MPG friendly gear</p></blockquote><p></p>
[QUOTE="swampratt, post: 3102054, member: 15054"] Oh yes .050" A camshaft is rated in Lobe Lift. and Duration and overlap and lobe separation angle and many other things. Lift is how far the peak of the lobe is away from the radius of the base circle of the camshaft. Or you can say Lift is how much it will lift the valve open. Lobe lift of say .300" will have the peak of the cam lobe .300" away from the radius of the base circle of the cam. Say you have .300" lobe lift you also have a 1.5 :1 rocker arm ratio. it will multiply .300 x 1.5 =.450" there you have .450" of valve lift. valve is opened .450" Now the .050" and duration. Duration advertised on a camshaft can be advertised as 290 duration or say 268 duration.. now that can be misleading . Because it is advertised and many times that advertised duration number could be at .006" valve lift or .012" valve lift. Manufactures do not always tell at what Valve lift "advertised"duration is calculated at. So a basic industry standard was set so we could compare a camshaft more easily and choose what we want. SO the .050" spec was set forth. Almost all cam manufactures will have the .050" spec for you too see in their advertisement. so 260 duration at .050".. means 260 degrees duration of that cam beginning the measuring process after the lifter was lifted .050" and end the measuring process when the lifter or cam follower is .050" from closing. So basically sliding up the lobe to start your measurement. now you can see advertised at 292 at .006 will be different than advertised 292 at .012" . It does not get any better ...050" is not the end all in comparing cams or trying to pick one and how they will act. You have duration at .200" lift also. you can have the same say 260 duration at .050" lift on 2 cams and at 200" lift one cam may have 138 duration and another will have 168 duration.. that 168 duration will make more power as it is holding the valves open much longer and allowing the cylinder to fill up with more air. This may explain some of it better. [URL]http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx[/URL] There are exceptions to the rule when reading what cam manufacturers post about overlap and Lobe separation angle. Most will state LSA Lobe separation angle if you make it wider say from 106 to 115 LSA the 115 LSA will have a more broad power curve and carry power farther past the peak HP rating. Say peak HP is at 5700rpm.. they are saying the 115 LSA will not drop power off a rapidly past 5700 rpm as a 106 LSA cam will. I found in my testing that is NOT true all the time. It has a lot to do with lobe events.. when the exhaust lobe is opened and closed and when the intake is opened and closed. I have had Odd cams speced for my little 350's and just recently I had an odd ball made in search for more MPG it had a wider LSA 112 but power past the peak fell off like a brick compared to the narrow 106 LSA. Both cams i compared in the same engine back to back both cams were ground with the same master lobe I just juggled the LSA .. but this experimental cam I only changed where the ex lobe would be.. left the intake lobe opening and closing rates the same between the 2 cams. My theory was I would not loose my Low speed power because I had 225 PSI cranking pressure and intake valve closing determines what that will be ..I did not want that to change as with high cranking pressures comes brute power out of the hole. Get the heavy vehicle moving. Big juggling act. That cam is what i am running now the 112LSA experimental in my 350. MPG went from 12-14 to 17-18 MPG. Peak HP was made at the same RPM on both cams 5700rpm but by 6500rpm the 112LSA was down over 40 HP. Normally you do not get to 112 LSA by moving the ex lobe only you move both lobes.. in doing that the intake valve would close later in the cycle and add a little more power on the top. Confused yet?? My cam grinder said I change cams like he changes underwear. :) I am always wanting to experiment. I almost wanted to have another made but go to 117 LSA and see if i could pull 22+ MPG.. this is normal driving with some spirited tossed in. not hypermiling. NO OD no FI and not a MPG friendly gear [/QUOTE]
Insert Quotes…
Verification
Post Reply
Forums
Hobbies & Interests
Gearheads
SBC Primer
Search titles only
By:
Top
Bottom
