Thread: Low Vacuum in 390

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If it will pull to 5000 rpms strong,you are not out of time at the cam. From what i can read on your cam sheet it isnt radical enough to kill the vacuum, plus you say the booster works. I would start over checking for a leak ,or a stopped up fitting.

Have you found your vacuum problem. I have a similar or same problem. I am running a elgin cam HYD .536 int and .562 on exh 75deg overlap. I am only reading 8-9inhg at the manifold and my c6 doesn't shift very good out of park. A big clunk. It shifts ok while driving. I have 20 inhg at higher rpm 1500 or above. I don't think I have any leaks but haven't check timing or valve adjustments yet.