Howdy all,

Been reading through a bunch of timing gear threads and I have a couple different "truths."

When installing a timing gear and chain on a 1968 Okds 455, assuming the #1 is TDC compression, the camshaft gear dowel should be at the 12 o'clock position, aligning the "0" marks on the new gear set. Or, #1 TDC compression, the dowel pin should be at the 6 o'clock position, leaving the alignment marks on the new gear set both at 12 o'clock.

When I took the old and loose chain and gears out, both marks on the old gears were pointed to the 10 o'clock position. Without knowing the dentify the camshaft, is it possible to have a ballpark advance setting for the cam?

Appreciate ya

 

I think the factory manual shows the cam gear mark at 6 and the crank gear mark at 12. Dont have a clue as far as the dowel pin goes, really does not matter.

 

Thanks again, Bill.
I have it set as the diagram implies. The dowel pin is at 12 o'clock on the cam sprocket, and both timing marks aligned: cam sprocket mark at 6 o'clock, and the crank sprocket at 12 o'clock. I realize this is just a somewhat educated WAG as far as cam/crank timing is concerned.

I have read a couple of posts suggesting the other way as well, but it would seem to me one of the settings would be 180 degrees out of timing...and that sounds messy.

thanks,
pigs

 

I dont have the factory manual here at the shop, I just had that picture. Dont know for sure on Oldsmobile but on Chevrolet when you align the marks like the picture it is actually on #6 compression stroke. So you have to turn it a turn to get it on #1 and put the distributor in.

 

The dowel pin is where the tab on the fuel pump eccentric goes. And once again, it doesn't matter if the marks are at 12-12 or 6-12. Just rotate the crank 360 degrees and you'll be at the other location. Verify compression at the spark plug hole.

 

The 2 positions are 12/12 or 12/6 crank vs cam gear (they are 180* apart) that the timing set can be installed. 12/12 is the #1 cylinder firing and the distributor rotor will be pointing to the #1 plug wire, or 12/6 would be the #6 cylinder with the rotor pointing to #6 plug wire. If you're following the instructions in the assembly manual when assembling the engine, they tell you to turn the engine 1 full turn after installing the gears at 12/6 to install the distributor on #1.

 

Nice! Thanks, gentlemen. Much appreciated. Happy holidays