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#1
03-30-2003, 10:51 AM
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i advanced the camshaft by 2* at the crank last week. the JP performance timing set has 2* keyways to the right and left of 0 on the crank gear; i put the gear on at the +2 keyway. my question is how much this actually advanced the camshaft; my buddy told me that 2* advance at the crank makes 4* advance at the cam. does anybody know for sure?
the frustrating thing is that i can't really tell if advancing the cam improved the car's performance because of traction issues. last night my mph was about what it had been, but the car was spinning the tires harder off the line. 97 Trans Am WS6 Best ET: 12.13 Best MPH 114.6 74 Formula 455 Best ET: 12.02 Best MPH: 112 |
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#2
03-30-2003, 10:51 AM
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i advanced the camshaft by 2* at the crank last week. the JP performance timing set has 2* keyways to the right and left of 0 on the crank gear; i put the gear on at the +2 keyway. my question is how much this actually advanced the camshaft; my buddy told me that 2* advance at the crank makes 4* advance at the cam. does anybody know for sure?
the frustrating thing is that i can't really tell if advancing the cam improved the car's performance because of traction issues. last night my mph was about what it had been, but the car was spinning the tires harder off the line. 97 Trans Am WS6 Best ET: 12.13 Best MPH 114.6 74 Formula 455 Best ET: 12.02 Best MPH: 112 |
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#3
03-30-2003, 09:12 PM
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The JP Performance set that I have is either 8 or 9 keyways, and they are marked in crank degrees. That is the first set I have had that is in crank degrees rather than cam degrees. It allows a much more precise adjustment.
http://www.jimspontiac.homestead.com/Index.html 
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#4
03-30-2003, 10:54 PM
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You probably should not be adjusting advance and/or retard on your cam unless you are degreeing the cam and encounter a specific problem requiring this measure, i.e. piston to valve clearance, etc., this according to the people I deal with that make cams for a living. If, for instance, your cam is ground on a 110* centerline and installs at 106*, you have 4* advance in your set-up. The cam grinders do not come up with these figures at random. The technology involved with developing todays grinds should not be second-guessed. Call your cam maker if you have any questions concerning your application, or call Comp Cams 1-800-CAM-HELP. These folks can shed some light, don't go by what "a buddy told you", as it will probably cost you horsepower...at the least! Ron.
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#5
03-31-2003, 07:09 AM
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OMT- mine too; i advanced it 2 degrees to the left of 0 (+2).
ron- i had solid reasoning for advancing the cam. what i wanted to know was if advancing it 2* at the crank equaled 4* at the cam. 97 Trans Am WS6 Best ET: 12.13 Best MPH 114.6 74 Formula 455 Best ET: 12.02 Best MPH: 112 |
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#6
04-01-2003, 03:54 PM
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this is great...somebody sent me an email today saying that it works in reverse of what my buddy said. geoff from australia said if i advanced the crank 2* it only advanced the cam 1*. if this is true i wasted my time and will have to do the whole thing over again.
97 Trans Am WS6 Best ET: 12.13 Best MPH 114.6 74 Formula 455 Best ET: 12.02 Best MPH: 112 |
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#7
04-01-2003, 04:04 PM
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It is true. That is what I was implying on my previous post.
http://www.jimspontiac.homestead.com/Index.html
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#8
04-01-2003, 05:32 PM
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fabulous...i guess i shoulda asked about this beforehand.
 97 Trans Am WS6 Best ET: 12.13 Best MPH 114.6 74 Formula 455 Best ET: 12.02 Best MPH: 112 |
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#9
04-02-2003, 02:40 PM
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Isn't it true that all the "degrees" numbers mentioned when talking about camshafts (so many degrees at .050 lift, so many degrees on centerline, etc.) are all talking about Crankshaft degrees anyways?
So it really does not matter how far the "2 degree key" moved the cam, but rather the crank. Your second buddy was right, every 2 degrees you spin the crank, the cam only moves 1 degree.  Cam has the BIG sprocket compared to the crank on the timing gears."Nothing Beats an Ol' Goat..." 
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"Nothing Beats an Ol' Goat." |
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#10
04-02-2003, 05:03 PM
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GoatRider - The confusion comes from the fact that most crank gears are marked in cam degrees, and cam offset keys are marked in cam degrees. It is uncommon for the crank gear to be marked in crank degrees, but the one in question is. Also, all cam specs are in crank degrees except the LSA. It is in cam degrees.
http://www.jimspontiac.homestead.com/Index.html
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