1972 350 Timing Tab

[CutlassCrusin]

The timing tab on my 350 engine is un-readable. I seem to remember that each pointer is 4 degrees off the next, but I'm not sure where TDC is. I know the proper tuning is 12D BTDC. Can anyone help with the markings?

[rocketraider]

The saw-tooth points are 4 degrees apart. Best ballpark I can give you is that TDC on the tab is about 45 degrees off vertical, and that is probably not accurate enough to set timing properly.

I'd get that tab readable. Degreaser and a wire brush will do wonders. Once you get it clean, a dab of white paint on the preferred degree mark will help you see it in future.

[CutlassCrusin]

Thanks Glenn

I can't get in there with a brush but by using Brake Cleaner I managed to clear the lines and see a "0". For anyone else who might need this, here what I can see (as best as I can re-create it).

/___

\___18?

/___16?

\___12?** Correct Timing

/___9?

\___4?

/___0

\___

___

[rocketraider]

You're real close. The "9" is actually "8". The timing tab points are every 4 degrees apart: 0, 4, 8, 12; and the vees are every 2 degrees, 2, 6, 10, 14. 1972 350-4v AT, factory spec is 12d BTDC @ 1100 rpm, with vacuum advance disabled and canister "carb" port plugged. I like to set timing with a vacuum gage in addition to the light (plus it's a good way to plug the vacuum advance line). Go for highest vac at normal curb idle speed and if it doesn't ping, diesel on shutdown or grunt starting, timing is pretty much where it needs to be.

[CutlassCrusin]

Thanks again. I guess you caught my typo. So then it should be:

/___12 ** Correct Timing

\___10

/___8

\___6

/___4

\___2

/___0

\___

___

How do you alter the vacuum? Or is that just a by-product of the timing?