At 07:27 AM 5/9/06, wkilleffer@comcast.net wrote:
>....
>The books all say to adjust to .015 cold, ..... I used a
>clik-adjust, .... and a feeler gauge. ....
Click adkist will not work at all if the adjuster screw hangs up in
the threads. When it does work it is only accurate to +/- one
click. The primary attraction for click adjust is, it's supposed to
be quick to use, and is may compensate somewhat for badly worn rocker arms.
A feeler gauge is as accurate as the flatness of the mating surfaces,
and depends somewhat on knowing how to use it.
You can adjust the valve gap on a stock MG engine without using
either a click adjust or a feeler gauge. Rotate the pushrod with
your fingers. Turn the adjuster screw down to close the gap until
the pushrod stops turning (zero clearance). Note the orientation of
the slot in the adjuster screw, and think of a position at right
angles to it (make an "X" with your fingers). Rotate the screw
anti-clockwise 1/4 turn (or 91 degrees if you prefer), and lock down
the jam nut. That's it, resulting in a perfect .015 inch gap.
It isn't magic. It is a result of 24 threads per inch and 1.42 to 1
rocker arm ratio.
The math is: 1/24 x 1/4 x 1.42 = 0.0148
You would have to miss the rotation angle by 6 degrees to have an
error of.001 inch.
>....
>This morning, I drove it to work, and the valves chattered ....
>
>Did I adjust things to be too loose? ....
I wasn't there to know if you did it right. There is a lot of
tolerance for crankshaft position when the valves are closed. You
can adjust the valve any time the tappet is sitting on the base
circle of the cam, which spans more than 1/2 rotation of the cam, or
more than one full rotation of the crankshaft. You can do it when
the piston is within 1/2 stroke of TDC on the compression
stroke. You can do that with the spark plugs in place just by
bumping the starter and letting the engine stop where it likes (near
1-2 stroke).
Using the rule of 9's, when one valve is open (by any amount) you can
adjust the complimentary valve. 1_8 , 2_7 , 3_6 , 4_5. With plugs
in, give the engine a bump. It will stop near half stroke with two
valves open. Adust the two compliments. In four steps you're done.
>My commute's about four miles each way. Will driving it that
>distance do damage?
The valves hwould have to be REALLY far out of adjustment to cause
any damage on a short trip.
>Also, is it true that the valves can be adjusted to .013 when the
>engine is hot/warm? ....
The gap difference between hot or cold is about .001 inch, and the
gap gets smaller with heat. So .014" hot is about the same as .015" cold.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
|