Engine timing 1925 Buick

[Hubert_25-25]

I am trying to make sure that I have this right.

On a modern engine, when you set the flywheel on TDC, if you were to pull the front timing cover, there would be 2 dots that are aligned on the crank gear and the cam gear.  You could be 1 crankshaft rotation off, but rotate 1 crank turn and you would have the dots aligned and touching and be on TDC.

 

Now lets take the case of the 1925 Buick.   The shop manual says to align the notch in the crankshaft gear with the dot in the camshaft gear.  I have no other marks on the gears.  The crank gear has a line, and the cam gear has a dot.  This is Photo 1.  When the marks are aligned.  

 

Oddly enough, this is not TDC.  If I roll the crankshaft to TDC, I have what is shown in photo 2.  The alignment marks appear to be 3 teeth away from touching.  

I want to put the timing cover on, but I want to make sure the engine timing is correct.  Am I set up correctly? 

So I should be set up for firing #1 or #6.  How do I know from the camshaft lobes that I am set up with correct firing for #1.  

Thank you,   Hugh

 

 

[JFranklin]

The marks on the gears are there just to index the crank and cam, not to determine TDC.

[ROD W]

Hugh,  This  1920 gear has two dots on one side and one dot at 180" ( infront of the Buick )  As per the cam/crank gear alignment plate ( for the 25 Master ) in the Shop Manual,  the two dots align with the crankshaft mark.   When the keyway is positioned as per the plate 26 in the Manual,  the two dots would align with the crankshaft marker. I had a look at a  25 engine I have out the back,  but could not see any marks on the cam gear.  Will have a better look tomorrow.

[ROD W]

As per the 25 Master Shop Manual.  It says to count  8 teeth spaces back  from  a line projected out from the keyway.  This gives the position of the single dot.  the two dots  are at 180" to this.  If the crankshaft is then turned through one  turn it should align with the single dot on the cam gear.  See what the 25 standard  Manual shows.

Edited November 2, 2018 by ROD W (see edit history)

[Leif Holmberg]

Here are a picture from Motor Care and Operation Standard models 1925.

Leif in Sweden.

[ROD W]

1925 Master Manual,  It looks to me as per plate 26, that when the flywheel is at TDC  the dots are 2-3 teeth out.

Edited November 2, 2018 by ROD W (see edit history)

[ROD W]

Here it is a bit larger. Count 8 teeth spaces for single dot.

Edited November 2, 2018 by ROD W (see edit history)

[Hubert_25-25]

Many thanks for the notes.  This is all very helpful.  I feel OK so far. 

The diagram that Rod posted is in the 1925 Buick Standard Shop Manual, but it is not entirely correct for a Standard Model.  Perhaps for a Master.  On the Standard, the distance between the keyway and the timing mark on the crankshaft is just less than a full tooth.  On the cam gear, the mark is 6 teeth from the keyway.  The first photo is a rubbing of the gears.  I assume the larger gears for the Master make the mark on the crankshaft about 1 1/2 teeth, and the camshaft is 8 teeth from the keyway like the manual drawing.  

Crankshaft gears: I have 2 crankshaft gears.  The mark is identical on both gears and identical to what is shown in the "motor car operation and care" photo.  The mark is a line and not a dot almost 1 tooth clockwise of the keyway

Camshaft gears:  I have 3 camshaft gears.  The single mark is identical on all 3 gears.  6 teeth clockwise of the keyway.  Only one of the 3 has the double marks 180 degrees around so I lined up single line to single dot.  This is #1 TDC firing stroke when I look at the cam lobes for #1.     

 Water pump gears: I have 3 water pump gears.  Here is another interesting one.  All 3 gears are marked differently.  In the second photo, the keyways are all to the left, but the timing marks are in different locations.   They must have marked these for reference as well, but the final is just to point the distributor to the #1 spot on the distributor cap being at the front and begin setting the point break and rotor location from there.

In photo 3, I added a dot with a drill on the back side of the camshaft gear on TDC for #1 firing.   If the water pump shaft is out, I can know if I am on the correct TDC and not 180 degrees off for #1 cylinder.  Without this, I would need to pull the engine side panel or the valve cover to know.  I will put a corresponding mark on the back side of the water pump gear as the marks are only on the front of the gear.  I intend to have the timing cover in place before I install the water pump shaft so I will line it up from the back side.

Hugh  

 

Edited March 16, 2022 by Hubert_25-25 (see edit history)

[Leif Holmberg]

Huge.

It dosen`t matter how the marking are on the water pump gear are stamped ,you have to adjust the timing on the distributor anyway.

I think those "water pump"gears  probebly has been stamped after they had been put in  place.?

The only importent thing are that gears on the crank and cam gears are puted together in right possition.(No matter how about pump gears are .)

Leif in Sweden.