reducing advance under boost
Thread Starter
Instructor
Joined: Apr 2006
Posts: 110
Likes: 0
From: wakefield uk
reducing advance under boost
I'd like to try reducing the amount of mechanical advance,I want to achieve about 26degs when boosted.Whats the best/accepted way to restrict the mechanism on a HEI distributor,and maybe lower the vacuum advance aswell.
Tech Contributor
Joined: Jun 2004
Posts: 20,905
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I'm assuming (and HEI mechanical experts please correct me if I'm wrong) that there should be a bushing or some way to restrict the advance weight movement, limiting the total mechanical advance to what you want. This timing limit would work well under boost. However, under light cruise conditions at higher RPMs, you're possibly going to be retarded in your timing curve. A vacuum can with a lot of advance might be able to compensate for the reduced mechanical advance, but still not affect the total timing under boost. Seems like some combination of those two items should get you in the ballpark of what you want.
Keep us updated on what you do, and the results.
Melting Slicks
Joined: Jul 2006
Posts: 2,373
Likes: 6
From: Baltimore MD
Would a msd unit with boost timing retard on it ,work for ya?Its what i have and a friend of mine.One is a computer car and the other is a hei unit.On my vette i just have the hei setup with weights and adjustable vaccum.I need the msd unit like my other vehicle.
Last edited by Billysvette; Jan 30, 2008 at 03:31 PM.
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
Along with the blower I upgraded to a Crane HI-6 R ignition which is by far the simplest and safest way to pull timing out under boost. You can dial in as much or as little as required...it ain't cheap, but neither are engine parts 
http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku
