Re: [alfa] Dial Indicators for Finding TDC

[Paul Bayly <thebaylys@xxxxxxxxxxx>]

Albert,  Good idea on confirming TDC.

Most dial indicators I work with have some means of being attached to a
sliding rod, which in turn is attached to a clamp or magnetic base.

Now obviously the magnetic base won't be any use on the alloy head, but a
suitably shaped iron plate simply held down across three head nuts will
suffice.This method would need a second pair of hands to rotate the crank.
By using three resting points instead of four there is no rocking of the
plate. There will be very little force applied to the indicator by the
piston so variations in readings shouldn't present any problems due to
distortion of the dial clamping device/attaching arm.

Alternatively, you could build some form of attachment using an old spark
plug, suitably hollowed out to allow the point of the indictor to feed thru
onto the piston crown.  You may require an instrument with a longer point
than standard.

The absolute value/measurement of the height of the piston relative to the
top of the block is irrelevant, so is it's relative 'squareness' to the top
of the block You are only after an indication of when the piston has reached
the top of its travel, and you will be measuring the rotation over only a
few degrees as you rock the crank.  Once confirmed as correct, you can go
back to using the pointer on the front of the engine.

Beatle
Oz
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