Crankshaft Pulley

[bcmc33]

What is the relationship between the crankshaft pulley keyway to TDC and the pulley TDC notch?

[mikealdren]

Brian,
I don't think there is a fixed relationship, the crank is machined and assembled and then the notch is cut to mark TDC for that individual part. If you fit a new pulley, it will need remarking.

I suspect that, with modern machining, parts can be marked on manufacture now.

regards
Mike

[denicholls2]

Brian,
I don't think there is a fixed relationship, the crank is machined and assembled and then the notch is cut to mark TDC for that individual part. If you fit a new pulley, it will need remarking.

Given that these are Ford parts, and Henry Ford was the pioneer of interchangeable parts in automobile manufacturing, I would be very surprised indeed if this were true. Establishing a fixed relationship between TDC on the crank and the pulley marks that is constant across parts is not rocket science, and avoids having your timing in some bizarre place when you replace the pulley for whatever reason.

Can this really be true? If so, good to know when building an engine from bits.

[bcmc33]

Common sense tells us that there is clearly a definite relationship - I just don't know what it is and thought someone on the forum would know.

I have just removed the radiator tonight and will remove the pulley tomorrow and do some measurements so that I can mark the toothed billet pulley I intend to use for distributerless ignition.

[bcmc33]

FWIW the crankshaft key is at 12 o'clock on TDC. Quite predictable, I guess.

The TDC notch on the pulley is 50 degrees from the from the 12 0'clock key position.

[john.p.clegg]

So the TDC mark on the frontplate is actually 50 B.T.D.C....(just to complicate things)

John

[billwill]

So the TDC mark on the frontplate is actually 50 B.T.D.C....(just to complicate things)

John

But but.... the markings on the front plate are also displaced the same amount...
So they cancel each other out...




Mind you I reckon it possibly would be easier to see the markings if they were in the centre, between the crank and the water pump.

[Galwaylotus]

So the TDC mark on the frontplate is actually 50 B.T.D.C....(just to complicate things)

John

Isn't that ATDC? Looking at the engine from the front that's just before 2 o'clock!