Re: dialling in cams (vernier gear)
How to dial in a cam.
First thing we need to establish is whether the harmonic balancer is showing true TDC, as it is quite common for the outer ring to slip with age.
There are several methods for finding TDC, but this is probably the easiest way for a beginner.
Screw a bolt into number 1 spark plug hole with the end of it protruding (say) 10mm down the bore.
Wind the engine over by hand (gently) until the piston hits the bolt. Make a mark on the harmonic balancer at the TDC indicator. Now wind the engine over backwards until the piston hits the bolt again. Make another mark on the harmonic balancer. Now, the point exactly between the 2 marks you just made on the balancer is true TDC, make another 3rd mark, this may be on top of the mark which is already in the balancer. Simple.
Now that we have found TDC we can move onto adjusting the cam.
You will need a dial indicator for this, and you also need to know (from the cam grinder) the 'lift @ TDC' figure, which might be (say) 0.040".
You will need to set up the clock so it measures the movement of number 1 intake valve, this is very critical and accuracy is important here.
Adjust the clock so it reads zero when the valve is closed, slowly wind over the engine by hand until you reach TDC. The valve should have started opening and you will have a reading of 0.030" to 0.050" depending on how close the cam is set up to ideal.
If it's perfect straight away, you don't need to go any further.
If it's out by more than 0.001" either way, you will need to move the cam either by the use of the your newly fitted vernier gear.
That's about it for now, I may have missed some minor details as I'm just trying to remember all of this from the top of my head, so if anyone can fill in the gaps, go right ahead.
If you also have any questions, fire away.
4L I6, naturally aspirated producing 173.5rwkw.
14.410 @ 96.49mph with street radials.
What's that?..... Did I hear you say TQE power?