3400 cam centerline

[TheProfessor]

sweet where were you wne i started the 3400 cam specs post

[bszopi]

I've been here for like 4 years... where have you been? Almost all of my info from my engine is posted somewhere on this site. My cam specs are listed in the 3100/3400 Performance Area under Cams.

[TheProfessor]

oh lol
yeah i guess i have seen it before

[Froggx]

This puts the inlet cam's centerline at 108* and the exhaust came centerline at 116*. Thanks for the help.

[Froggx]

Just wondering one thing about the cam. On the cam card it shows a picture of two circles representing the intake and exhaust timing, and has a section marked overlap. However, when I do the math for the overlap I come up everytime with the cam not having overlap. Am I doing my math wrong or is the picture designed to confuse people new to cams?

[geoffinbc]

LOL no you must be doing it wrong. All cams have overlap. Even very mild ones have some.

[RacerX11]

Exhaust closes -9 degrees Before TDC (or +9 degrees After TDC)
Intake opens -1 degree After TDC (or +1 degree Before TDC)

This adds up to 10 degrees of overlap (9 +1)

Marty

[Froggx]

Yeah, I thought I had ruined that somehow. Somebody forgot to keep track of a negative

[Froggx]

Now that I look at this, and I might be quite stupid again, the stock came with duration 196* @ .05" has 9* duration less than that regrind on each side of a lobe centerline. This means 18 degrees less between the the two lobes. Working with 10* overlap I do 10* - 18* = -8* of overlap for the stock cam. What am I doing wrong this time?

[TheProfessor]

are you doing the math with crank or cam degrees

[Froggx]

Cam... I think.

[TheProfessor]

try it the other way and see what happens