I will be setting it up with a degree wheel and dial indicator. I read on the forum that someone found a RPM 300 with a 108 centerline instead of the advertised 112. So I figured I would want to check the specs anyway. If all checks out correctly I'll probably go with the 2 degree advance. Chuck

Rono

The last two "True Roller" sets that I used I had to set them 6* advanved to get them to the specs on the card.

If you’re relying on aligning the marks on the gears to time the camshaft and not using a degree wheel and dial indicator to accurately phase in the camshaft, it’s going to be pot luck on where the camshaft is actually installed.  Said another way, “If the camshaft is not setup with a degree wheel and dial indicator, you will not have a clue where it’s really installed other than the marks are aligned”.  Although checking the cam phasing is typically performed on the #1 cylinder, be sure to move the dial indicator that’s being used over to the #6 cylinder and also check both the intake and exhaust lobes.  The degree wheel reads TDC for both #1 and #6 so this is just a dial indicator movement from the tappets on one cylinder to the tappets of another.  If you get more than a 2° difference between the #1 and #6 cylinders on either the intake or exhaust lobe centerlines, do some rechecking.  If necessary check all the lobes on all cylinders.  There are some cams out there that are sloppy in this regard and now is a good time to catch any discrepancies in the cam grinding itself.

Also remember that a camshaft ground on 110° lobe centers installed straight up will actually be 110° intake lobe centerline.  This means that the exhaust will also measure at 110° exh lobe centerline.  If the intake lobe centerline calculates out at 108°, then the cam is 2° advanced and in this mode, the exhaust will read 112° exhaust lobe centerline.  The amount the camshaft is ground on doesn’t change but the phasing of that ground lobe centerline in relation to TDC does change. In the 2° advanced scenario, the 108° and 112° being added together and then divided by two still adds up to the original ground 110° lobe centerline.

There is a way to approximate what the cam timing is on an assembled engine without the aid of a degree wheel.  Assuming the damper is accurate at TDC, then the rockers on #1 or #6 cylinders can be caught when they are both slightly equally depressed and level (overlap mode) and then measuring the distance from TDC on the damper in degrees.  The damper marks sitting a given number of degrees before TDC would have the camshaft advanced that much while after TDC would have the camshaft retarded.

Depending on what you plan to do with the engine, drag race or town cruiser, I beleive on a previous post somewhere a couple years ago on the subject, it was stated that Normally advancing the cam will give better low end torque if you want a tire fryer. retarding will give more top end HP in the higher rpm range. Ted or John may be able to explain the scientifics of this.

Advancing the camshaft essentially closes the intake valve earlier which in turn makes for an increase in the cranking compression.  This in turn increases the low end torque values.  Whereas advancing the camshaft works well for a naturally aspirated engine, on a boosted engine there is an increase in torque related directly to the increase in filling cylinder pressure.  This increase in filling cylinder pressure increases the torque without having to put additional advance on the camshaft to achieve the same thing as is done with a naturally aspirated setup.  There's actually much more to this but this is the simple explanation.