I figure that's an appropriate title to the post since it's what I'm doing,
and it's not working.
Turn crank (clockwise on a Midget 1500) until TDC is determined. Use a
dial indicator to center the crank on the dwell period.
Place a dial indicator on the pushrod for the 2nd lobe of the cam, which is
the intake valve of the # 1 piston.
Turn the cam shaft clockwise until it is on the heel of the cam (the lowest
height of the pushrod)
Turn the cam shaft clockwise until the pushrod just begins to creep upwards
(leave it at that exact point).
Turn the crankshaft the appropriate # of degrees to match this event. See
below:
The specs on my Piper 284 cam are 284 duration, Maximum height at 106
degrees ATDC, 36-68, 68-36, which means that the intake opens 36 degrees
BTDC. So you turn the crank 324 degrees in the clockwise direction, ending
up 36 degrees BTDC.
The math is simple.
On a 284 duration cam, maximum lift is achieved at 142 degrees (284 / 2:
half the spin to open, half to close).
If maximum lift occurs at 106 degree ATDC, then you subtract 142 from 106 to
get 36 degree BTDC.
It closes 284 degrees later, which is 248 degrees ATDC, or 68 degrees After
Bottom DC (ABDC).
That's it. Put on the cover, and crank pulley, and fire it up. Or try..
Alternatively, you can turn the cam clockwise until the pushrod reaches it's
maximum height.
Go back a forth a few times to center the cam on the dwell (i.e. it's at the
maximum height for a few degrees of spin, so center it).
The turn the crank clockwise 106 degrees, which is the listed distance for
maximum lift on the lobes.
Does this sound right to anyone? Ed?
TKs,
Mike
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