Posted By: 426runner
Cam installed centerline question - 11/02/10 09:40 PM
What would be the affect on an engine if the cam was installed at 105 c/l when the card said it was meant for 108 deg c/l?
Quote:Is this a joke? Retarded?
Your engine will be retarded !
The intake valve opens later and closes later. Since it closes ABDC that's a hair less compression the motor will make. Likewise the exhaust valve will open sooner, releasing combustion pressure sooner. All this equates to a loss of power.
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Your engine will be retarded !
The intake valve opens later and closes later. Since it closes ABDC that's a hair less compression the motor will make. Likewise the exhaust valve will open sooner, releasing combustion pressure sooner. All this equates to a loss of power.
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Your engine will be ADVANCED.
The intake valve opens earlier and in turn will close earlier. Since it closes ABDC that's a hair more compression the motor will make. Likewise the exhaust valve will open sooner, releasing combustion pressure sooner. All this equates to a loss of power.
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yes it's confusing as a smaller # ie 105 vs 108 means sooner (advanced) as 5 o'clock is sooner than 8 o'clock. the intake valve reaches peak lift at 105 deg past TDC INDUCTION stroke (which is sooner) than if it reached it at 108 deg past TDC INDUCTION stroke (& therefore closes sooner). As said it shifts the power band lower & reduces the valve to piston of either the intake or ex valve (I forget which one). Cams I've advanced (street) which you'd be doing (to 105) have always benefitted from it (more torque)
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double it and divided by two
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Heres a somewhat related question about cam timing...
If I have an adjustable timing chain with multiple keyways on the crankshaft gear, and they are marked 0, +1, +2, +3, -1, -2, -3, etc...
Lets say I have a lobe separation angle of 106*
If I set the timing gear so that it is in the +2 slot, does that mean I am advancing the camshaft 2 degrees so that its now 104* or does that mean that I am adding 2 degrees to the 106* number? 106+2=108?
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double it and divided by two
How long has it been since you had a basic math class?
Quote:I'm w you here as cam theory is (sort of) Greek to me & I need it (the obvious) spelled out so I can grasp it.
I have found that sometimes it helps to make things clear to state the obvious.
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Heres a somewhat related question about cam timing...
If I have an adjustable timing chain with multiple keyways on the crankshaft gear, and they are marked 0, +1, +2, +3, -1, -2, -3, etc...
Lets say I have a lobe separation angle of 106*
If I set the timing gear so that it is in the +2 slot, does that mean I am advancing the camshaft 2 degrees so that its now 104* or does that mean that I am adding 2 degrees to the 106* number? 106+2=108?
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Another related question... It is always recomended to check the installation of the cam for the proper centerline as called for by the manufacturer. Most all write-ups or videos that show the process end up with the CL coming out correct. Mine didn't. My installation calculated out to 105 instead of 108 like the card said it should. Why would this happen? What factors could contribute to the cam not being as the manufacturer says it should be out of the box? And yes, there were 2 of us there during the degreeing process and we did it over and over and came up with the same 105 every time.