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FoT=20
I'm building a motor for a club member and am having some difficulty with c=
am timing specs. It's an APT=20
cam and the spec sheet they provided is not only nonsensical but it has som=
e of the data crossed out and=20
some of the numbers hand written in. No real usable data on timing it for i=
t's best performance. At best it's really=20
more of a fast road cam. I didn't spec the cam or buy it. It has 108 degree=
lobe centers, .280 lobe lift and a=20
duration of 270 degrees at .020 lift. The data sheet says Time to ATDC 103 =
- 104 degrees and it's supposed to have=20
.071 lift at TDC. This cam won't do both.=20
When I time it to 104 degrees ATDC=C2=A0at full lift I get 9 degrees BTDC a=
t .071, which also translates to 20 degrees BTDC at .050 lift=20
which to me sounds more reasonable. I've contacted APT twice now and the fi=
rst answer was a lot of jibberish and they=20
haven't answered the second inquiry yet regarding the math that will not wo=
rk.=20
What I don't want to do is inadvertently RETARD the cam. I'm used to workin=
g with .050 for valve opening but APT doesn't consider=20
.050 an open valve.=20
Any advice would be more than welcome.=20
jim g=20
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<html><body><div style="font-family: Arial; font-size: 12pt; color:
#000000"><DIV>FoT<BR></DIV>
<DIV>I'm building a motor for a club member and am having some difficulty with
cam timing specs. It's an APT</DIV>
<DIV>cam and the spec sheet they provided is not only nonsensical but it has
some of the data crossed out and </DIV>
<DIV>some of the numbers hand written in. No real usable data on timing it for
it's best performance. At best it's really </DIV>
<DIV>more of a fast road cam. I didn't spec the cam or buy it. It has 108
degree lobe centers, .280 lobe lift and a </DIV>
<DIV>duration of 270 degrees at .020 lift. The data sheet says Time to ATDC 103
- 104 degrees and it's supposed to have</DIV>
<DIV>.071 lift at TDC. This cam won't do both.</DIV>
<DIV>When I time it to 104 degrees ATDC at full lift I get 9 degrees BTDC
at .071, which also translates to 20 degrees BTDC at .050 lift</DIV>
<DIV>which to me sounds more reasonable. I've contacted APT twice now and the
first answer was a lot of jibberish and they </DIV>
<DIV>haven't answered the second inquiry yet regarding the math that will not
work.</DIV>
<DIV>What I don't want to do is inadvertently RETARD the cam. I'm used to
working with .050 for valve opening but APT doesn't consider </DIV>
<DIV>.050 an open valve. </DIV>
<DIV>Any advice would be more than welcome.</DIV>
<DIV>jim g</DIV></div></body></html>
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_______________________________________________
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http://www.fot-racing.com
Archive: http://www.team.net/archive
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