Vacuum Advance - Yes or No?
Thread Starter
Racer
Joined: Oct 2006
Posts: 269
Likes: 7
Vacuum Advance - Yes or No?
My high performance 406 is almost ready for the dyno. I am being asked if I want a distributor with vacuum advance or not. The engine builder is suggesting no vacuum advance.
I do not understand the implications of Vacuum Advance vs No Vacuum Advance so I would like some info from our Forum members with large inch small blocks that have made this decision.
What did you decide and why? What are the benefits / tradeoffs?
Thank you
I do not understand the implications of Vacuum Advance vs No Vacuum Advance so I would like some info from our Forum members with large inch small blocks that have made this decision.
What did you decide and why? What are the benefits / tradeoffs?
Thank you
Tech Contributor
Joined: Jun 2004
Posts: 20,921
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I take it your engine builder is stuck in the 60's.
Do yourself a favor and read the Ignition sticky (all of it, including the corrections). A vacuum advance system is more than just "road hugging weight", another concept the old timers believed in.
Do yourself a favor and read the Ignition sticky (all of it, including the corrections). A vacuum advance system is more than just "road hugging weight", another concept the old timers believed in.
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
Street driven cars need vacuum advance, as it adds in lead under low-load conditions. It compliments centrifugal advance. If you operate at a single rpm level (like a dragster) you optimize lead for that rpm level, so you do not need vacuum advance. In a nutshell, engine rpm dictates centrifugal advance; engine load dictates vacuum advance.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
As far as the engine is concerned, it doesn't get impacted by a vacuum advance can except at idle or low throttle cruising conditions. And, if you select the correct vacuum can for your engine's vacuum capability, having one will make idle and low cruise more comfortable and easier on the engine. There is NO DOWNSIDE to having a vacuum advance system on your car. It can only improve low throttle operation. When you 'mash the pedal', there is no vacuum produced by the engine anyway, so it's a moot point. If you want the engine to have 'good manners' at idle put one on the dizzy.
Thread Starter
Racer
Joined: Oct 2006
Posts: 269
Likes: 7
Melting Slicks
Joined: Mar 2009
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