Thinking about this Howard’s cam

Here are the timing numbers I get.

Howard’s:

EVO: 67 BTDC
ECL: 110 BTDC
EVC: 27 ATDC
IVO: 32 BTDC
ICL: 102 ATDC
IVC: 56 ABDC

268/270 106/102

My numbers:

EVO: 75 BBDC
EVL: 112 BTDC
EVC: 31 ATDC
IVO: 29 BTDC
ICL: 106 ATDC
IVC: 61 ABDC

270/286 109/106

Looking at the numbers, and like I see a lot most of the extra 12 degrees of exhaust duration 75% of which went to Exhaust Valve Opening. So an extra 8 degrees on the exhaust opening side.

Equally interesting is with only two more degrees of intake duration it opens the intake valve 3 degrees later but closes the valve 5 degrees later.

Crap I forgot to calculate overlap. I’ll do that next.

Also interesting is the Howard’s cam with its 4 degrees of advance doesn’t center the overlap triangle.

My numbers with 3 degrees advance centers the overlap triangle.

I’ll run the overlap numbers.

Is that a typo?
The Howard’s advertised numbers at 50 are 268/274
You have 268/270 above
Btw, I appreciate your info, it’s very enlightening!! :thumbsup: