I just don't get it, what am I missing

[RacingJake]

Check my cams today and this is what I got at .050,

Intake open at 15 and close at 122

Exhaust open at 120 and closed at 21

Using the info below I get 143 on the intake and 139 on the exhaust. This sound to high or is it.

To Degree Cams:
Install degree wheel and find TDC with a positive stop. Setup dial indicator on valve and zero indicator with valve closed. Rotate engine until valve is .050" off seat and write down reading on degree wheel. Continue to rotate engine until valve is .050" from closing. Note the number.

To figure lobe center for intake cam subtract opening number from closing number, divide difference by two and add that number to 90. For the exhaust subtract the closing number from the opening number and follow the same formula.

What about this formula ??

R1 + R2 + 180 / 2 - R1


Example: R1 = 15 R2 = 59

15 +59 +180 = 254 (duration)

254 / 2 = 127

127 - 15 = 112?

I get 143 intake and 40 exhaust

I know it's something simple that I'm doing wrong but what is it??.

Also the degree wheel only go to 180 degrees then goes back up, is that right or do you need one with 360 degrees.

Lost and there's no more beer in the cooler

 

[RacingJake]

Found out my formula was for a 90 degree wheel and I was using a 180 degree one. I can now see how someone can do alot of damage by using the wrong wheel/formula.

 

[biker66]

Hmmm, think I recognize that example... :wink:

You've got your numbers wrong.
I don't have access to a degree wheel right now.
But, my guess is that 122 really is 58 degrees and 120 is 60 degrees, which gives:

Intake:
15+58+180/2-15=111,5

Exhaust:
60+21+180/2-21=109,5

Better now ?

EDIT You beat me while I was typing.... /EDIT

 

[RacingJake]

Don't tell anybody but I got that formula from Biker66, OK

Thanks
Jake

ps I do feel alot better now

 

[RacingJake]

So now I know my intake is at 111 degrees and my exhaust is 109 degrees.

I did advanced my intake until it was at 109 too, valve to piston was no closer than .065 from 4-10 degrees ATDC. Tried to crank the bike and it didn't turn over as fast. I'm thinking at 109 the intake is closing earlier by a few degrees upping the compression.

I did try 96 degrees and the valve to piston was like .010 so I changed it back. It doesn't take that much adjusting to make big changes.