Timing light vs Vacuuum gauge

[forestb]

I was wondering if it is better to use a vacuum gauge to adjust timing or a timing light. It seems like from what I have heard that the vacuum gauge will help you time the engine in a way that is more engine specific while using a timing light is more general. But maybe using a vacuum gauge will not give you total timing?

[skyphix]

Using the vacuum gauge just gives you vacuum, but it can be used to help set the appropriate timing for the engine. I'd use both, to be honest... one to give me ideal timing, and one to tell me what that ideal timing is. A timing light will also let you recurve the distributor for maximum power output, and also adjust in case your engine detonates at max vacuum (too much timing for the octane and/or condition of the engine.)

Of course, grain of salt... its been a while since I was messing with carbs and distributors.

[Ziegelsteinfaust]

Timing is separate from engine vacuum in a few key ways.

A traditional sbc or BBC likes 36* total timing , and a initial timing of 12-15* initial. With 20-22* of mechanical advance. Anything over 36* advance with the vacuum advance removed, and power starts rolling over. Plus hard starting. Under 32* your leaving power, and mileage on the table.

Modern sbc or BBC heads, and your in the 28-32* range most of the time. With 32* usually being the best guess unless you dyno it.

LS heads and 26*-30* from what I hear is about right. I never tuned one personally. I had my truck tuned.

Vacuum is more of the carburetor being adjusted right, but only hints at air fuel ratio being close. Even if it is on the lean side vacuum maybe fine.

Timing effects vacuum as a lazy engine puts out less then if it is tuned right.

You really need both as they have individual purposes that can not be just condensed.

[forestb]

Ok thanks guys