[Fot] GT6 cam timing advice

[toodamnfunky at comcast.net]

FoT 
I'm building a motor for a club member and am having some difficulty with cam timing specs. It's an APT 
cam and the spec sheet they provided is not only nonsensical but it has some of the data crossed out and 
some of the numbers hand written in. No real usable data on timing it for it's best performance. At best it's really 
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 
duration of 270 degrees at .020 lift. The data sheet says Time to ATDC 103 - 104 degrees and it's supposed to have 
.071 lift at TDC. This cam won't do both. 
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 
which to me sounds more reasonable. I've contacted APT twice now and the first answer was a lot of jibberish and they 
haven't answered the second inquiry yet regarding the math that will not work. 
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 
.050 an open valve. 
Any advice would be more than welcome. 
jim g 
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