Michael D. Porter wrote:
> Gary Klein wrote:
> >
> > Scions,
>
> > I disassembled the sprockets and chain, rechecked and reset #11 & 12
> > valves and followed this procedure again but nothing changed from the
> > first time.
> >
> > So, here are my questions:
> >
> > 1. Did I follow the correct alignment procedure today?
>
> Yes, but you're probably adhering to a registration mark on the cam
> sprocket noted with an earlier sloppy chain.
^^^^^^^^^^^^^^^Yeah, I think you're right.
> > 2 If the answer to #1 is yes, would the engine have run with the cam
> > timing being off by 1 tooth?
>
> Since the answer is yes, and no, the answer to this question would be,
> "maybe."
>
> > 3. Where do I go from here?
>
> Use only enough of the chain assembly procedure not to violate common
> sense. The cam sprocket was scribed with an old chain, and the new crank
> sprocket cannot have a previous mark. The official GT6 workshop manual
> for the six-cylinder provides the following for valve timing with
> unmarked sprockets, which seems to differ slightly from your procedure
> in the Bentleys:
^^^^^^^^^^^^Differs, yes, but it also appears to be essentially the same
idea measured in another fashion. When #1 piston is at TDC, both the #1 &
#2 valves should be both closed, right? Following Bentley's proceedure for
#11 & #12, my #1 & #2 valves are fully closed, reading .010 gap.
Maybe I got it right? Suspect that the new tight chain is the source of my
confusion.
> "Temporarily attach the camshaft sprocket and turn the camshaft until
> number 12 pushrod has reached its highest point. In this position,
> adjust number 1 rocher clearance to 0.040" (1 mm).
>
> "Repeat the procedure with number 11 pushrod and adjust number 2 rocker
> until its clearance is identical of the number 1 rocker.
>
> "Again turn the camshaft until numbers 1 and 2 have reached the point of
> balance, that is, when one valve is about to open and the other is about
> to close.
>
> "Turn the crankshaft to bring numbers 1 and 6 pistons to TDC."
>
> Fitting Timing Chain
>
> "Exercising the greatest care, remove the timing sprocket without
> disturbing the camshaft. Encircle both sprockets with the timing chain
> and offer up the camshaft sprocket to the camshaft.
>
> [This applies to single, rather than dual sprockets, but I would guess
> the TR6 dual sprocket works the same way, and this may be where your
> difficulties lie in using a new crank sprocket, new chain and old cam
> sprocket]
>
> "NOTE: The camshaft timing sprocket is provided with four holes which
> are equally spaced but offset from a tooth centre. Half tooth adjustment
> is obtained by rotating the sprocket 90 degrees from its original
> position. Quarter tooth adjustment may be obtained by turning the
> sprocket back to front. By turning back to front and rotating 90
> degrees, three-quarters tooth adjustment is obtained."
>
^^^^^^^^^^^^^I wasn't aware of this but will check it out later today. The
cam sprocked has 42 teeth and 4 drilled center holes. It seems logical to
me.
> > 4. The cam chain is a bit snug. Is this typical for a new chain?
>
> Yes.
Thanks Michael.
Gary
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