Reply to "351C typical vacuum readings"

panteradougMember

Disconnect the vacuum hose to the power brakes and see if this helps.

I think you should have around 14-15 inches with that cam but if the power brake diaphragm is leaking, you would wind up with a low vacuum like this.

OH! Don't forget about the power valve in the Holley carb. If it is blown out it will have the same symptoms and with the hassle of breaking in the new cam often gets overlooked and just one backfire will blow it out.

These things are absolutely horrendous now and even will blow out with the check valve installed. Genuine Holley parts are best but it is now a comparison between just plain crap and complete s hit.

Just because it is a new carb doesn't mean that you didn't blow out the power valve on first start up?

You need a power valve tester to know for sure. Otherwise you are just chasing dillusions.

2/15/1812:41 PM

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