Got Time?


Seems like there’s a whole lot of confusion over this timing an engine stuff.
That said, here’s what works for me.
At least what works for me on the GM engines, but the information is pretty much applicable to the other brands as well if they are modified.
If the other brands are stock, you would do well to use the stock timing curves and advance methods.

We’ll go over initial advance, vacuum advance, centrifugal - or as some call it, mechanical - advance, full time vacuum and ported vacuum.
Other than noting that camshaft advance or retard is something completely different from ignition advance or retard I’ll just point out that camshafts are set to place the torque curve peak in a particular place as well as for smog requirements on some engines.

Low end - rpm wise - torque requires the camshaft advanced.
In most cases no more than 4 degrees BTDC. (Before Top Dead Center)
The great majority of cams, both hot and stock are installed straight up as the saying goes.
Retarded cams are usually found on smog motors.
Retardation due to the indexing on the timing gears.

Degreeing in a camshaft is a requisite for building serious engines and it doesn’t hurt to do it with engines that are not so serious.
A not so serious engine perhaps exemplified by a stock compression 350 SBC with modest cam, modest carburetor size and a reasonable for the street intake manifold and at the least duals and better yet, small primary tube headers.

For the not so serious engines, simply installing the cam on the marks will suffice.
I’ve done more than a few of these, degreed them to boot and found that at the most they were off 1 - 1 1/2 degrees. Entirely reasonable for a street engine and indicative of the quality work that cam grinders do.
Play in the timing chain is more than likely the reason why the cam doesn’t degree in right on the money.

In fact, even if you want to run a cam “straight-up” on the street, it’s probably a good idea to advance it a couple of degrees to start with.
Timing chains stretch to a certain point right away and stretch even more over time.
My thinking being, if you start straight-up when the chain stretches, the cam timing is going away.
With the cam advanced to start with the engine will remain in an overall better state of tune for a longer period of time.

One big caveat here: Don’t confuse cam timing with ignition timing.
They are entirely separate.
If you find an ignition timing point that your engine likes, you can always return to it regardless of where the cam is dialed in.
Reason being, the cam and the ignition are separately adjusted devices.