<div dir="ltr">it seems most of the better cam grinders these days have some very fancy software for examining the motion of the valve for any cam/valve train being proposed. They can easily calculate the critical acceleration and deceleration limits for any valve train mass and its not hard to 'plot" the motion of the cam/valve lifter, even if they did not create the actual cam being studied. Ive done this on my lathe with a data capture system,. Ive just finished a major exercise with one cam maker on my Toyota 4AG race engine where I suspected valve train harmonics were responsible for a broken cam (actually snapped in 2 at peak rpm) . valve spring makers like PAC in the USA are known to have such software.<div><br></div><div>it seems like many TR cam profiles were created in the ancient past, possibly more by trial an error than serious maths. Thats not to say they are wrong/bad, but rather there is a more modern alternative that might have a place. Some cam makers may be using such approaches with TR cams, but I suspect many are just churning out what they did 30 years ago. . <br><div><br></div><div><div><div dir="ltr" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>Terry O'Beirne</div></div></div></div></div></div></div></div></div></div></div></div></div></div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Feb 22, 2020 at 2:14 AM Larry Young via Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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Yes, the down side to a smaller clearance is that the seat-to-seat
duration and valve overlap will increase causing a loss of the low
end. This page > <a href="http://tildentechnologies.com/Cams/Tip_Lash.html" target="_blank">http://tildentechnologies.com/Cams/Tip_Lash.html</a>
shows a case where the duration would increase about 32 degrees to
about 4x86 = 344 degrees. I like to call this the "tuning fork
effect" it sets of all kinds of vibrations which can cause the valve
to jump off the lifter and bounce off the seat at closing. <br>
<br>
I did not intend to imply most smack the lifter, just that many do.
This is a good reason to thoroughly measure your cam profile. Most
stuff on the web talks about valve springs as the only cure for
valve float issues.<br>
- Larry<br>
<br>
<div>On 2/20/2020 6:51 PM,
<a href="mailto:van.mulders.marcel@telenet.be" target="_blank">van.mulders.marcel@telenet.be</a> wrote:<br>
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<div>Larry, you say most camshafts smack the lifters hard. Will
a smaller valve clearance relieve this a bit? Has it
disadvantages to set the clearance smaller than
recommended?(except that the valves will run hotter)</div>
<div>Marcel<br>
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