Vacuum Advance Check Valve & Boost Referencing

[fang16]

Boost referencing two Holley 1000 CFM for a 6/71 blown Dart 434 and was wondering if a Standard Motor Distributor Vacuum Advance Check Valve placed in the vacuum line would prevent injury to the power valves in case of a backfire?

[Gaz64]

You need a suspended type valve that will be open in both directions, for vacuum or normal boost pressure. The ball should be forced up to seat if a sudden high pressure spike occurs. Or you could use a 3 port solenoid triggered by a vacuum switch, the power valves can then see the manifold vacuum (closed for cruising), and then be vented to atmosphere to stay open, anytime the manifold pressure is above your opening point. The power valves won't see the manifold pressure spike if your switch and solenoid are fast acting. Gary