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I re-wired the ignition system in brother's Superformance Cobra yesterday (we had problems with the Durapsrk system so we went with the MSD 6AL set up). All went well except upon start up the engine made a very loud, high pitched, whistle/squeel through the carb. My brother shut it off virtually imediately and no matter what adjustments I made, it wouldn't go away. The engine is a '65 427 side-oiler, with Edlebrock aluminum heads, etc (was professionally built, is rather healthy, and has approximatley 5000 miles on it). Prior to the ignition change, he had replaced the intake manifold gasket. He also adjusted all of the valves.

The sound is not mechanical sounding, I believe that it's the sound of air being forced back up through the carb, as if an intake valve wasn't closed all the way during the compression stroke. We re-adjusted all of the valves and checked compression on all cylinders and they were fine (150 -155 psi). What could be the problem? If it was an old engine, I'd suspect a slipped timimg chain, but this engine is barely broken in. Any sugestions or ideas are welcome, no matter if they are wacky or not!

Thanks in advance for your wisdom, this place continues to be an invaluable resource! (Thanks, Bob)
 

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I don't have an answer for you but go over anything that you changed since before the repairs. This past week has been horrible for me at work with broken airplanes and each snag has been after someone changed something.
Hose off when doing valves or running new wires, hose slightly damaged (cracked) and making a poor seal. Enough to whistle but not lean out the engine enough to affect idle.
 
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