[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: Timing belt

> A good dial indicator will set anyone back more than a few bucks, so I 
> wouldn't recommend the use (or purchase) of one to those other than 
> reallllly serious shadetree mechanics.

Nonsense ... just about every pawn shop in the known world will have several
for sale at any given time (don't forget to negotiate the price!) and if you
insist upon buying one new, Harbor Freight Salvage sells some decent & cheap
ones that will work just fine.  For $20 to $50 (tops), you're in business.
> To check the lobes on the number one cylinder does not require the
> removal of the valve cover, just pull the oil cap off and use a
> flashlight.

If you simply want to check that the cam lobes are still there or the cam's
at approximately TDC, this method will work fine.  If you want to make sure
the cam's at TDC, you'll need to pull the valve cover, place a straightedge
across the lobes and use either a machinist's rule (measures to 1/64") or a
depth gauge to measure the height from the head on either side.  If the cam
is symmetrical, it'll be at TDC when the two measurements are the same.  It
will take a few more minutes than lining up the dot on the cam sprocket but
it's a lot more accurate not to mention a good excuse to upgrade to the new
style rubber valve cover gasket that doesn't seem to leak nearly so much as
the old style cork ones did. 

Of course, to determine when the piston is at TDC, you'll still need to use
a dial indicator but you can get close by using a machinist's rule down the
No. 1 spark plug hole and turning the engine over slowly by hand.  It helps
to have an assistant turn the motor over while you keep an eye on the rule;
when you see it just start to drop, make a note of the crankshaft position,
then turn the motor the other way until it just starts to drop again ... if
you split the difference between these two measurements, you'll be close to
TDC.  You also need to make sure the angle of the rule doesn't change as it
moves up and down, and make sure to use one that is long enough not to fall 
in at BTDC!  Still, dial indicators are cheap enough, I don't see the point
in not using one unless you're doing the job on the side of the road and in
a big hurry...

BTW, assuming you DO rigorously line up both the cam and piston at TDC, the
odds are that you'll find the timing belt won't fit perfectly ... they seem
to always be a half-tooth out!  As such, I find the best way to do this job
is to line up the bottom end first, fit the belt, then dial-in the cam with
an adjustable sprocket.  I'm running 6 degrees of advance on my 200q and it
does improve the low-end response noticeably (now that I'm used to the car,
anyway ... at first, I couldn't tell any difference!).

HTH ... I've done this job at least 15 times over the past 10 years and I'm
finally getting pretty good at it!  :^)

     _             _             
    / l       l o l  \       l o   Jeffrey Goggin
   /__l l l / l l l  l l l / l l   * * * * * * *
  /   l l_l \_l l l__/ l_l \_l l   AudiDudi@delphi.com