Impala SS427.com Message Board

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power brake vacuum source

Posted by Ken P <iframe src='https://members5.boardhost.com/impalass427/info/user=ratcayne' width='330' height='300' border=0 style='border:none;'> on 8/11/2020, 5:29 am

Just wondering did chevrolet use a steel tube to route vacuum from the rear of the intake manifold to approximately the left head to supply vacuum to the power brake booster on a '69 427/425? And also was that nipple in the rear of the intake just for the power brakes or was there also a nipple off of it for another vacuum source (hose) ? My car never had power brakes but I'm adding them.

Re: power brake vacuum source

Posted by Nick <iframe src='https://members5.boardhost.com/impalass427/info/user=427impalasportcoupe' width='330' height='300' border=0 style='border:none;'> on 8/12/2020, 10:14 pm, in reply to "power brake vacuum source"

Hey Ken P. I own an original 69 Impala SS427 with L72 425 hp 4 speed with vacuum power brakes. The vacuum come from the back of the Holly carb. The engine produces low vacuum and the brake pedal gets very hard after a fast stop. I am installing a pump from Summit Racing to correct this fade. Do not use a cheap one as they are noisy and do not work well. Maybe get a better booster than original. NICK L72

427impalasportcoupe

Re: power brake vacuum source

Posted by Ken P <iframe src='https://members5.boardhost.com/impalass427/info/user=ratcayne' width='330' height='300' border=0 style='border:none;'> on 8/13/2020, 11:14 am, in reply to "Re: power brake vacuum source"

Thanks for the reply. I have a 4346 Holley carb and there is not a vacuum provision on the back of the carb.The only large one is for the PCV valve,right side on the base plate.

Re: power brake vacuum source

Posted by Sluggo <iframe src='https://members5.boardhost.com/impalass427/info/user=sluggo' width='330' height='300' border=0 style='border:none;'> on 8/11/2020, 4:35 pm, in reply to "power brake vacuum source"

The best place to find your answer is the factory assembly manual. Detail can be found under the option code sheet(s)

Re: power brake vacuum source

Posted by Ken P <iframe src='https://members5.boardhost.com/impalass427/info/user=ratcayne' width='330' height='300' border=0 style='border:none;'> on 8/16/2020, 3:01 pm, in reply to "Re: power brake vacuum source"

Thanks.Took some time to find it but it is pictured in the assembly book.

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