1973 mercruiser 140 cam shaft

[beericks]

Hello guys,

I dunno if you guys remember me but I had a problem of my motor eating distributor drive gears. Come to find out the cam shaft is shot. When I removed the cam I forgot to mark the position of the timing gear to the crankshaft. I was wondering if there was a simple way to remedy this problem. The crankshaft doesn't look like it has a mark on it but the timing gear does have a mark. I can remember where the position was within a tooth but I want to be sure.

 

[Fishermark]

Re: 1973 mercruiser 140 cam shaft

There will be a mark of some sort on both gears - either a circle or a dot. Just line them up. Like this:

 

[beericks]

Re: 1973 mercruiser 140 cam shaft

Will all crankshafts have this mark? I didn't see one on mine. Can I just put the motor at tdc and then use the mark on my timing gear?

 

[Bt Doctur]

Re: 1973 mercruiser 140 cam shaft

all crankshaft gears have it ,not the crankshaft pre se. I dont recommed this but 4 teeth counterclockwise in relation to the keyway and the dot on the cam.
cam timing has NOTHING TO DO WITH PISTONS OR TDC

 

[beericks]

Re: 1973 mercruiser 140 cam shaft

Ok thanks so much. Just to clarify though... the mark on the crank gear is matched up with the mark on the timing gear and the motor should be at tdc

 

[Fishermark]

Re: 1973 mercruiser 140 cam shaft

Ok thanks so much. Just to clarify though... the mark on the crank gear is matched up with the mark on the timing gear and the motor should be at tdc

To install the gear correctly, simply match up the marks as indicated. You don't need to worry about finding TDC - simply line up the marks. Look carefully for the dot - as you can see in the pic, it is pretty small.

One thing to remember - when it comes to putting the distributor in. THAT'S when you will need to find TDC on the compression stroke. When the marks are aligned, you are not on the compression stroke - the distributor will be 180 degrees out.

 

[beericks]

Re: 1973 mercruiser 140 cam shaft

Thanks so much