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#60716 05/21/2006 10:02 PM | Joined: Nov 2000 Posts: 582 Shop Shark | | Shop Shark Joined: Nov 2000 Posts: 582 | Just finished setting up the mechanical linkages for my dual Holley Webers and Offy intake. Langdon's says to use the vacuum ports off the Holleys for the distributor advance (above the throttle plate). Vacuum line is going to Langdon's mini HEI with vac advance. I've seen where others have apparently used the vacuum port on the Offy. Any advantage of one over the other? If using the Holley port, I assume that you hook to both and not just one via a tee in the line. Want to set up the vacuum line(s) once and not redo it if one is better. | | |
#60717 05/22/2006 1:57 AM | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Use the port on the carb, the advance needs to run on ported vacuum to get the proper signal to advance/retard the timing. Using the port in the manifold won't allow for that as it is a constant vacuum.
Bill Burmeister
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#60718 05/22/2006 4:13 AM | Joined: Jun 2005 Posts: 887 Shop Shark | | Shop Shark Joined: Jun 2005 Posts: 887 | The instructions with my HEI from langdon said to try ported and un ported (direct from the manifold), one carb and two, to see which way works better.
The vaccum in the intake isn't actually constant-it varies with RPM and depends in part on the cam- a bigger cam produces less vacuum is the general rule. So, ported might not be enough.
'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi
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#60719 05/22/2006 2:54 PM | Joined: Nov 2000 Posts: 582 Shop Shark | | Shop Shark Joined: Nov 2000 Posts: 582 | Thanks. Will use both ports to see how it does. | | |
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