My understanding would be a little bit different but it has been looong time since I was into performance cams and tweaking speaks.
I believe the #'s would be
- 268 degrees duration (how long the cam holds the valve open) between start and finish for both intake and exhaust. This # was always a bit less precise as manufactures noted the start and finish at different increments of lift).
- 218 degrees duration between lifter up .05" and back down to .05" (both intake and exhaust and the more standard duration most people go by)
- .300" lobe lift (both intake and exhaust)
- .480" total valve opening lift for int and exh which is the lobe lift (.300) times the rocker ratio)
- 108 degree lobe separation angle between peak points of intake and exhaust. (The lower the # the more overlap you have.)
Looking at the shop manual the stock total exhaust lift is .466 and the intake lift is .427 so this cam has considerably more (12.4% more) total intake valve lift, which can definitely add more power. I remember on the small block chevys about .5" total lift was about the limit you would want to push them.
I don't see this cam having any affect on vacuum or vacuum controlled components. 108 degree lobe separation is pretty typical... and I did a quick check on other #'s and don't see anything out of the ordinary. Very mild additional exhaust lift, a bit more aggressive intake lift...neither of which is going to significantly alter vacuum. The lobe separate, again is typical..if it was a very low # you would have a lot of overlap which can cause some loss of pressure. Duration of lift is also pretty typical.
Hey, I found the specs from the mild HP gain cam I bought thru Kanter:
It is listed as Camcraft Performance Cams with the following specs:
Part #: 83-1818-10AZ HCR
Advertised Duration: 268 / 268
.050 Duration: 218/218
cam lift: .300 / .300
valve lift: .495 / .495
center line lobe separation 108 / 112
The only spec I see different is the valve lift and that is a computation of the cam/rocker ratio multiplier. My card has the rocker ratio listed as 1.65, so 1.65 x .300 = .495.
So, the .300 cam lift is the constant and of course a hard #. To see which total lift is correct you can simply look at the shop manual to determine the actual cam/rocker ratio multiplier:
Intake: .427/.258 = 1.65
Exhaust: .466/.283 = 1.65
That means your total valve lift is 1.65 x .300 = .495.
WE HAVE THE SAME CAM. They just miscalculated your total valve lift because they used a multiplier of 1.6 instead of the correct 1.65.
And my car runs great with that cam!!!!
The exhaust bolts becoming loose would be a function of metal to metal heat-cooling expansion contraction, and gasket compression and it is recommended that you re-torque bolts after you run-in the engine... probably right after the initial 20 to 30 minute run-in and then say after 500 to 1000 miles. and it never hurts to check torque later. I have about 3500 since my rebuild and this is probably a good time for me to check my bolts again. I have had no issue with exhaust bolts coming loose with this manner... just a need for a slight turn in to bring back to spec.
Not sure what you mean by "sucking in on the exhaust idle?"