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Timing Gears dot to dot

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TulsaFred

TulsaFred

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Putting the timing chain, gears, cover, damper, etc back together today after fixing leak (see previous thread on this).

I did not rotate engine while it has sat waiting for parts.

I think I remember rotating timing gears "dot to dot" before removing them.

Now putting it back, it appears that dot to dot on the timing gears is TDC of Piston #1 on the exhaust stroke, rather than the compression stroke.
Is this correct?

Just want to be sure before putting it all back together.

Fred
 
Keith_M

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I think that if you line up the gears dot to dot they will only fit with the woodruff keys one way. In other words, if the gears will go over the woodruff keys and they are lined up dot-to-dot it has to be right.

Keith
 
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TulsaFred

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Keith_M said:
I think that if you line up the gears dot to dot they will only fit with the woodruff keys one way. In other words, if the gears will go over the woodruff keys and they are lined up dot-to-dot it has to be right.

Keith
Click to expand...

That makes sense, but I suppose the engine could have been rotated with gears off, in which case if the crank rotated one turn, with Cam unchanged in position, keys and marks could still line up, but be out of phase.

Right now the gears are on dot to dot and the rotor is pointing to number 4, not number 1.
 
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When in doubt I always just used my own setting w/ #1 TDC and both lobes for that cylinder pointing EQUALLY down (unless OHC depending on style). Even if you sight it slightly wrong the teeth should correct you in the right direction.
 
Keith_M

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TulsaFred said:
That makes sense, but I suppose the engine could have been rotated with gears off, in which case if the crank rotated one turn, with Cam unchanged in position, keys and marks could still line up, but be out of phase.

Right now the gears are on dot to dot and the rotor is pointing to number 4, not number 1.
Click to expand...

I don't think it matters because for the crankshaft, a compression stroke is the same as an exhaust stroke. Since the distributor works off the cam, you will always fire at TDC compression.
 
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TulsaFred

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OK guys, thanks.

Still, the nagging question, though...dot to dot is TDC on exhaust stroke? For some reason, I would guess that dot to dot would be TDC on compression.
 
Keith_M

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Can't remember if the distributor on a Sprite engine can be put in 180 degrees out. The compression vs exhaust stroke is determined by the camshaft not the crank. As long as the distributor is in correctly, you should be OK.

I just checked my service manual. It says line up the gears dot to dot and fit the woodruff keys. It doesn't say anything about making sure the distributor is pointed at 1.
 
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Keith_M said:
I don't think it matters because for the crankshaft, a compression stroke is the same as an exhaust stroke. Since the distributor works off the cam, you will always fire at TDC compression.
Click to expand...

Right but it will be 180 out because cam is half, power stroke is always dot-to-dot and exhaust would be 180 on the other side of the geR. I say that but given how squirrely these things say to be tuned, it wouldn't surprise me if they did line up on the exhaust stroke
 
dklawson

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Put your mind at rest. Dot-to-dot cam timing will put 1 & 4 at TDC and as you have found, #4 is on its firing stroke... not #1. Your setup is correct.
 
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TulsaFred

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dklawson said:
Put your mind at rest. Dot-to-dot cam timing will put 1 & 4 at TDC and as you have found, #4 is on its firing stroke... not #1. Your setup is correct.
Click to expand...

Thanks Doug. Maybe this thread will help someone else down the road.
 
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