How to align Crankshaft/Camshaft marks on my 1930 Studebaker Dictator 6?

[richard m]

My crankshaft gear has two "0" marks on adjacent teeth.  One has an additional punch mark next to the "0".  I assumed that I would set the cam gear "0" mark so it aligns between the two "0" marks on the crank gear.  However when I do that and then tension the idler sprocket, the cam gear mark does not line up between the two "0" marks.  It is 1/2 tooth off.  If I move the cam gear one tooth clockwise or counter clockwise  it still is 1/2 tooth off.  Is it possible that the crank gear tooth that has the "0" with the additional punch mark is what I should be aligning the cam gear to?  When I do that, the gear marks line up.  Thx, Richard

[richard m]

Well, no replies to my question about aligning timing marks.  Good news is I think I have answered my own question.  For the benefit of others who might need to make sure their timing is correct, I offer the following free advice.  When there are two marks on the crank gear and one on the cam gear, the standard convention holds that you align the cam mark between the two crank marks.  Any other marks on the gears have no meaning with respect to timing.  To confirm that I had the correct crankshaft/camshaft alignment I referred to my Dyke's manual (1922 edition) which covers this in detail.  It seems pretty straight forward.  You bring #1 piston to TDC on the stroke where the intake valve is just about to open. You can verify TDC by checking that the "TDC I-6" mark on the flywheel lines up with the pointer that is seen thru the small inspection plate Studebaker provided on the right side of the flywheel housing.  To make sure that the intake valve on #1 is about to open, remove the valve cover on the side of the engine and you can watch the cam lobe come around to raise the tappet on #1 intake valve as you approach TDC.  You should be able to feel free play or valve lash between the valve stem and the tappet. As you reach TDC there will be virtually no valve lash as the valve is about to open.  The intake valve actually starts to open about 10 degrees after TDC and Studebaker engineers fortunately put a second mark "INT OP I-6" on the flywheel so you know precisely when the valve is supposed to open.  According to Dyke's, if your #1 intake valve opens within 1/2" of the "INT OP I-6" mark on the flywheel when the piston is just past TDC, your crank/cam gear marks should be in alignment.  If they are not, you will have to loosen the timing chain tensioner (the gear that also drives the accessory shaft) to provide slack in the chain so you can move the cam gear to bring it into alignment with the crank gear.  When all is correct, the two marks will align when timing chain is properly tensioned and the flywheel marks show that you are at TDC on the intake stroke.   If I have any of this wrong, I hope the experts will chime in.  It will be a while before I complete my engine assembly and put this timing setting work to the test.