The problem with trying to feel TDC is that at this point of the crank
journal travel, it is traveling perpendicular to the piston movement. For
several degrees on either side of TDC, the piston has very little movement,
so TDC is very hard to detect. This is why I recommended using a "positive
mechanical stop for the piston just below the top of its travel". With the
piston maybe 1/4 inch below TDC, there is still measurable travel in the
piston for every degree of crank rotation.
Watching a straw or dial indicator will yield results with a margin of error
of several degrees. But it is useful as a gross check for timing chain skip
or harmonic balancer slip.
Dave Homstad
56 Dodge D500
-----Original Message-----
From: Forward Look Mopar Discussion List
[mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of Ray Jones
Sent: Sunday, July 06, 2008 10:28 PM
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Subject: Re: [FWDLK] 331 hemi timing questions
It will, it's just that a straw or soft stick like a fireplace match
will work just as well and require no setup.
Ray
On Jul 6, 2008, at 10:22 PM, Mike Apfelbeck wrote:
Why wouldn't a dial indicator work through the spark plug hole? It
should be a straight shot down the plug hole to the piston dome on a
hemi.
Mike
At 03:01 PM 7/6/2008, Ray Jones wrote:
> You contradict yourself, John;
> You state that you also use an indicator in the plug hole...... What
> you and others say are great for an engine on the stand, but not for
> an installed engine.
>
> The straw in the plug hole works very well for an INSTALLED engine,
> since it's near impossible to put on a degree wheel in a car that's
> operable. The straw will get him in the ballpark and will tell him
> what the marks on his pulley are. That was the original question.
> Ray
>
> On Jul 6, 2008, at 1:56 PM, John McCann wrote:
>
> That doesn't work because there are several degrees of crankshaft
> travel when the piston is at the top of it's travel with no visible
> movement of the piston, the method David described is very accurate
> and the method we used to find TDC in Radial airplane engines using a
> degree wheel and an indicator in the spark plug hole.
>
> John
>
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