[SOLVED] setting timing belt properly 1973 50hp 500

dave37

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Sep 20, 2004
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See solved at bottom for solution

Have read through the posts concerning this subject, can't quite find my situation as I seem to have more factory marks on my flywheel. Prior to changing the distributor drive belt, I made marks on the pulley plate to align with marks made on flywheel (using a straight edge and a marker) but something doesn't seem just right. Engine runs, but not well, was running fine before the belt change.

My flywheel has a number of factory marks. The marks notched on my flywheel are thus: 2 factory lines on the outer edge of the flywheel which are a couple of millimetres apart, plus a factory paint dot above the first of these marks. There are two similar marks that roughly align with the distributor when the flywheel is placed at TDC.

I have yet to confirm TDC by putting a straw down onto piston #1 but will tomorrow to ensure that what I think are the factory TDC marks on the flywheel really are but as it runs, they probably are. Have a Seloc manual which isn't much help. When using the set of marks with the paint dot to align the flywheel to the TDC there are also 2 similar marks on the flywheel that align with a line on the pulley plate, but don't align with the arrow on the distributor drive gear. Engine runs, but a bit rough. I used a straight edge and a marker to mark things before I took the belt off and aligned everything back up using those marks just in case things got messed up.

Was told by a local repair shop to put the flywheel to TDC, and then use a straight edge set over the centres of the crank and distributer shaft, and align the arrow on the distributor pulley with the straight edge. I can figure out TDC easily enough using a straw down cylinder #1, but I'm wondering about the two sets of double marks, should the TDC pointer and the distributor arrow point between the 2 marks? Oh yeah, I don't really have a timing pointer but there is a timing degree sticker at the front of the engine at the top, but it is also confusing as a few degrees clockwise from the sticker's TDC is a raised line cast in to the metal.

So with that background I guess my question is this: If I confirm TDC with a straw down cyl #1, which marks should the distributor arrow (on the distributor drive gear under the belt retaining plate) point to, or can I use the method described by a local shop using a straight edge over the centres of the shafts, and if out by half a tooth, which way should I go, clockwise or counter clockwise to set the belt?

Any help great appreciated.

[SOLVED]

using a metal ruler and a strong magnet to hold it to the flywheel, ensured I was at #1 TDC using a straw down #1 cylinder, then using the magnet to hold the ruler lined up the rule with the mark (notch) on the flywheel with a bit of white factory paint in it up with the center of the crankshaft and distributor drive shaft. Ensured that the TDC mark on the flywheel was still at TDC on the indictator (very easy to move slightly). Then lined up the arrow on the distributor drive gear with the ruler (it's too easy to be out quite a bit if using just the arrow and the notch on the flywheel), put it all back together, runs like a charm!
 
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