Hi Rob.
I may be wrong, but I think for method 2 you need to have symmetrical lift
profiles or identical intake and exhaust lift profiles which I'm pretty sure
this cam does not.
I used method #1 and was only able to get within about 3 degrees, so you're
doing better than I was. How did you locate TDC and the max valve lift of the
cam? If you just try to look where the dial indicator stops moving, you can be
off quite a bit. This is because there is not much motion at these points. The
Crane Cams web site (and other referernces)gives a procedure for doing this.
There are two methods described there. One requires that you know the angle of
.050" lift which I didn't have. So, I used the other method.
Someone suggested using the other set of holes in the cam sprocket to get
closer. This may work for you. It didn't for me. Both sets of holes on mine
seemed to be in the same position relative to the sprocket teeth.
Just to put things in perspective, I recall there are 24 teeth on the crank
sprocket and 48 on the cam. This means one tooth is 15 crank degrees. So, you
can't do much about being off by one degree. My powertrain design gurus tell
me that this is nothing to be too concerned about.
Hope this helps.
- Hugh
Rob Christopher <robc@cisco.com> wrote:
> Hi listers (and Hugh in paticular if you are out there)
>
> I gave my best shot at indexing my TR6 engine on Saturday. My problem
> is I seem to be getting conflicting results using two measurements.
>
> Method 1: Instructions included with the Piper 270 cam say to turn the
> crank to 112 ATDC, find the maximum lift point of #1 intake and chain
> the two things together at that point.
>
> Method 2: Measure the lift of #6 intake and exhaust and find the
> crossover point where they are both open the exact came amount (0.038"
> in my case) meaning #1 are closed, put #6 and #1 at TDC and chain the
> two together at that point.
>
> My problem: Do method 1 and then measure the intake and exhaust of #6
> at TDC. The intake is open 0.040" and the exhaust is open 0.035", not
> equal amounts. Disassemble and do method 2. Rotate the crank and cam
> until #1 intake is fully open and measure 111 ATDC, not 112 as it should
> be.
>
> Am I being too picky about this? Is 0.005" or 1degree within reason?
> Does the assymetry of this cam mean I cannot do Method 2 to begin with?
>
> Rob in Ottawa
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