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Re: TDC Location on Crank Pulley

To: Hugh Fader <hfader@usa.net>
Subject: Re: TDC Location on Crank Pulley
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Tue, 30 Apr 2002 09:58:53 -0400 (EDT)
On Mon, 29 Apr 2002, Hugh Fader wrote:

> I have seen statments like "If you trust your TDC mark" on the lists. So, I
> checked TDC on my crank pulley and discovered that it occurs when the
> pointer is at 2 BTDC. I also see a slot cut into the mark at 4 deg ATDC. I
> have a new crank. I assume that someone, maybe the factory, calibrated the
> pulley to the old crank at 4 deg ATDC and that is what the slot is for.
> 
> Anyone have insights on this?
> 
> - Hugh

The "tuners" like Kas Kastner indicate that the rubber in the harmonic
dampener can move around a bit. This makes precise timing hard to do. To
remedy the situation, they would take the dampener to the machine shop and
drill a hole through the pully into the inner part of the dampener. Then
when they watned to get precise timing, they  would insert a pin to hold
the two pieces in unison.

FWIW, the flywheel generally has a mark for TDC. Set that (with a pointer,
e.g. rotate clockwise to TDC, set the pointer then counterCW to TDC and
set the pointer - it should line up with the verticle mark on the rear
engine plate. Then put on your timing cover and "set the pointer"

This way, at least you have exact TDC when you first fire the engine.

I've had a couple of dampeners that were up to 4 degrees off (I just moved
the pointer on the timing cover to accomodate this).

Good luck. 
rml
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