Vacuum Advance?
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Joined: Sep 2000
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Vacuum Advance?
I have a 77 Vette with 350/4spd. I just put in new distrib. Should I connect the vacuum advance? If yes, should it be connected to full vacuum at idle, or ported vacuum? What is most people running. The only change to engine is Crane HV272 cam.
Thanks
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Instructor
Joined: Apr 2006
Posts: 114
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From: Spring Texas
After setting the base advance, now connect the vacuum. The distributor will advance and the engine will run faster due to the vacuum.
Hope this helps.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
To set a distributor with vacuum advance, you first have to remove the vacuum. Set advance to about 7 degrees BTC with your engine running about 7K to 7.5K RPMs (depends on your cam). This is a good place for a stock 350 and a bunch of 383s to start the engine from.
After setting the base advance, now connect the vacuum. The distributor will advance and the engine will run faster due to the vacuum.
Hope this helps.
After setting the base advance, now connect the vacuum. The distributor will advance and the engine will run faster due to the vacuum.
Hope this helps.
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,364
From: At my Bar drinking and wrenching in Lafayette Colorado
Yes, you want to run vacuum advance.
No, you do not want to set timing to 7 degrees at 7K rpm.
First, you want to make sure the vacuum advance control unit you are running is matched to your engine's vacuum at idle. If you have a 272 cam, you likely want to run a VC1862 vacuum advance control unit to assure that the vacuum advance will pull its full range in at idle. Run it off of manifold vacuum for best idle quality and throttle response. For specifics on vacuum advance and control unit specs, e-mail me for my spec paper.
Set timing (with the vascuum hose disconnected) to 36 degrees total. For specific instructions on setting total timing, you can e-mail me, or see Barry's sticky on timing at the top of this Forum section.
V8FastCars@msn.com
No, you do not want to set timing to 7 degrees at 7K rpm.
First, you want to make sure the vacuum advance control unit you are running is matched to your engine's vacuum at idle. If you have a 272 cam, you likely want to run a VC1862 vacuum advance control unit to assure that the vacuum advance will pull its full range in at idle. Run it off of manifold vacuum for best idle quality and throttle response. For specifics on vacuum advance and control unit specs, e-mail me for my spec paper.
Set timing (with the vascuum hose disconnected) to 36 degrees total. For specific instructions on setting total timing, you can e-mail me, or see Barry's sticky on timing at the top of this Forum section.
V8FastCars@msn.com
Melting Slicks
Joined: Feb 2002
Posts: 2,625
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From: Cut n Shoot TX
