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Old 12-08-2012, 08:39 PM
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cam decreeing with the 50 method

I'd like to degree a new camshaft with the opening and closing figures at .050 tappet lift off the base circle of the cam rather than the intake centerline method but i'm having trouble knowing what numbers to look for on my cam card. Can someone tell me what numbers on this card I should be looking at when I come off the base circle to .050?

I can't type this exactly how the card shows the numbers because the site left margins everything but hopefully someone will understand.




intake exhaust

Duration at .050 216 228

Lobe Lift .3533 .3350

Separation 109. OP - CL OP - CL

Timing Events .050 1 35 45 3

Duration at .006 270 283

Gross valve lift .530 .503

Degree intake lobe to 107

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Old 12-09-2012, 05:28 AM
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The 0.050" duration specs are probably IO BTDC/IC ABDC EO BBDC/EC ATDC, but to be sure post a link to the cam specs.

Last edited by cobalt327; 12-09-2012 at 05:33 AM.
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Old 12-09-2012, 08:57 AM
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In this case i would use a degree wheel and dail indicator and make a map with a peice of graph paper. Its a pita but will tell you what the lobe actacully looks like not all cams and cam cards actually measure up. Best to map it out then you will know all the numbers you are looking for. Use the graph lines Running up and down as degrees and the ones running left to right as measure of lift at the degree. Then you can map the cam and make any calculations or data points you needs.

Last edited by hcompton; 12-09-2012 at 09:01 AM. Reason: Corrected grid lines.
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Old 12-09-2012, 01:28 PM
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use your duration numbers @ .050, plug them into this calculator Wallace Racing - Cam Degree Calculator, then you will have your open/close figures that you need to look for when degree in your cam @ 50
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Old 12-09-2012, 04:25 PM
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Thanks guys I think I've got the idea now, the Wallace Calculator helped me to see the numbers I needed to looked for at .050 off the base circle. I'm going to give it a shot in the morning. I've always just done the dot to dot but I'm getting more particular in my old age. If I can't get it to match the numbers on the card {now that I know which ones to look for} I'll be back with more questions, thanks again.
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Old 12-12-2012, 08:05 PM
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Timing Events .050 1 35 45 3

Those @ .050 events are in order intake open intake close exhaust open exhaust close.

Those are the numbers you should read on the degree wheel. You have to measure a lifter with a dial indicator. When the intake lifter raises .050 the degree whell should read 1 and .050 before it lowers completely it should read 35. Etc.

I always use valve events to degree inn a cam. If the intake opens at 3 it's retarded 2 degrees
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Old 12-12-2012, 08:31 PM
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Transposed numbers

Quote:
Originally Posted by cobalt327 View Post
The 0.050" duration specs are probably IO BTDC/IC ABDC EO BBDC/EC ATDC, but to be sure post a link to the cam specs.
Exhaust should read: EO ATDC/EC BBDC.
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