Whistling sound

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Oct 6, 2006 | 04:46 PM

craigl58

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From: pa

Whistling sound

I just installed new cam, lifters, heads,and intake on a 390. I am hearing a whistling sound when I rev the motor. I am sure I got a good seal on the intake.
There's a 600 holley on it.When I adjusted the fuel mixture setting to get the highest vacume I turned the screws out about one full turn and only came up with 16 lbs of vacume. Assuming the factory carb setting was out one and a half turns this seems like too much. Could this be the power valve? It must be running rich when its cold, it loads up the plugs and stalls. After it warms up it idle's fine, but I still hear the whistle when I hit the gas. Thank's for your help Craig.

Oct 6, 2006 | 05:25 PM

mswift

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Make sure you are not sucking air at the bottom of the carb, where it mounts to intake....

Oct 7, 2006 | 03:21 AM

craigl58

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From: pa

I"m just about posotive I don't have a leak there ,but I'll check there and everywhere again. thanks Craig

Oct 7, 2006 | 10:17 AM

Ford428CJ

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From: Klamath Falls OR

Some Holleys do Whistle. I have a 4011 800CFM that does it and a Moded 750DP that does it too. It doesn't hurt to check everything but I will bet its the carb!

Oct 7, 2006 | 11:14 AM

craigl58

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From: pa

Ok that would be good. Is 16 lbs of vacume acceptable? I thought 17 to 19 was what I was looking for. And it seems the fuel mixture screws are adjusted out pretty far. I'm going to take a look at it rigt now. Thanks Craig.

Oct 7, 2006 | 11:21 AM

Ford428CJ

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From: Klamath Falls OR

Use a little propane torch (Like for sweating pipes). Make sure the car is started and wormed up. Turn on your gas on the torch (don't light it). Then go around the intake and the base of the carb with it. If your idle picks up.......YOU GOT A LEAK LOL. I hope this helps.

Oct 7, 2006 | 12:24 PM

76supercab2

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Ok, I only bring this up because it burned my butt when I rebuilt my Holley. After finished, I installed the carb with the new carb-maifold gasket packaged in the kit. Had a leak at the base in back of the carb. Turns out the new gasket that came with the kit was shorter than the original and uncovered the vacuum passage that the EGR connects too. I ended up reinstalling the old gasket and solved the problem. Use the propane torch, starting fluid or brake or carb cleaning fluid. IF you find a leak at the rear of the carb, pull the carb, flip it over and see if the bottom gasket covers the entire base of the carb.

BTW, vacuum is measured in inches of mercury. Abbreviated InHg. Not pounds. It makes a difference in that the force created by the vacuum (absence of atmosphere) depends on the atmospheric pressure on the other side of the item that has the diaphram. IE at 28 inHg (total vacuum) at sea level on a diaprham, the force on the diaprham would be 14 pounds per square inch. On top of a mountain where atmospheric pressure is lower, the force would be less.

Good luck finding the leak.