Inliners International Forums General Discussion Engines Cam timing difficulty

I understand how to time a cam , if everything is how it's supposed to be , ie marks all in the proper place .... BUT

I have changed the fiber cam gear on my 216 and it has a different mark location than the old one.
I have checked the used spares I have and they are different to the engine also .

I am TOTALLY confused. This is not how this is supposed to work.

So , my question is this .

Does someone have a link to a tutorial I can follow to time this cam starting from no marks (apart from the ball on the flywheel.)

Thanks for your time.

Timing gears are made as a set and should be swapped as a set. Differences in tooth pitch can lead to premature gear wear and lead to other problems as well if you just replace one gear and not both of them together.

Yes , I understand that is true in an ideal world , however this cam gear was offered as an individual part # item and is all I have here .

Hi Dusty . . .

The old car manual project has the Shop Manual online. It describes the valve adjustment process:
TOCMP: 1949 Chevy Shop Manual
It includes an alignment diagram which is based on the number one exhaust valve - not much use because the crank position is before TDC . . . :-(

The crank shaft key-ways are aligned to TDC. With the crank key-way pointing straight up the #1 piston will be at TDC. You should find a single 'dot' on the crank gear. With the engine at TDC it should be pointing at the center line of the cam.

On the cam gear you should find either 1 or 2 'dots'. If it is two then the crank gear dot should go between the two. It is one they should align.

The key-way on the cam is aligned to the lobe center of the #1 it intake lobe. It should point at roughly two o'clock when the timing marks are aligned.

With unmatched gears you should check for lash play with a feeler gauge and for alignment with a straight edge across the two gears. The cam retainer plate can be shimmed with a gasket(s) to correct alignment issues.

regards,
stock49

Thanks very much for the key way information , I think that will set me up ok.

Regards

On three cam gears that I have in my possession the timing mark is between the 12th and 13th tooth clockwise from key-way.

Thanks , that is how my new cam gear is .

Can you see what tooth is the crank gear marked at ?

There are 4 teeth counter clockwise from the crank gear key-way (it seems to straddle a valley to the right and a tooth on the left - so 5 if you count the one partially above the key-way).

Great information.

Thanks very much for your time , I appreciate your efforts.

Thanks for your help , it was the crank gear with the different marking .

All good now .

Now that you have seemingly sorted out your problem, let me offer some additional advice. Now would be a good time to double check the cam phasing as well as tdc. Use a dial indicator on the top of the position and confirm that you have tdc on the compression stroke, i.e., that the cam opening and closing events are correct when the piston is at tdc. cam phasing on the six is critical because of he way the combustion chamber is laid out and how close the intake is to the piston. I once had new gears that were mismarked. Installed them, thought all was well until every intake valve hit the top of every piston and bent all of them. cheap insurance. Just a thought.

Let me guess. I long razor thin line from the center of the gear through the timing tooth? I have read about after-market gears marked in this way.