tapping noise after shut-down in rebuilt 302

There is a distinct tapping sound coming form the intake manifold(new Edelbroch 289 Performer). This sound will occur even if I turned the motor over a few times with
the coil disconnected(no fire-up) so I dont think its from a hotspot. Have new heads on, engine has run about 10 mins total since rebuild. Will a bad water flow/pocket make this noise? Its not faint at all, sounds like the gerbils are trying to hammer their way out....
Thoughts?
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Would prefer more information, did you have oil pressure? But, first things first. Are all of your accessories (alternator, power steering pump, etc) installed and secured?
Pull your valve covers and crank the engine with the coil wire disconnected, check to see if all of your push rods are in place and your rockers are installed correctly and properly torqued. Crank your engine and watch your rocker arms to see if the noise is around the same speed as your rockers. Will indicate valve train issue. If the noise is much more faster than your valve train, than it is the rotating assembly.
Was a tool left under your intake?
Frank

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I should note that this tapping occurs after I shut the engine down, for about 30 seconds it lasts, almost rythmic, i'm thinking its a cooling related problem. It even occurs when the engine is cool and cranked over with the distributor disconnected.
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wrote:

Very useful
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Just wanted to follow up -
after running the engine for an hour or two after the rebuild, the sound has not reoccured. Perhaps it was an air pocket the needed to work its way out....
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