y-block manifold vacuum


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By Ol'ford nut - 12 Years Ago
What amount of vac do you think I should be able to get with a stock rebuilt 292. I was reading that with my power brake conversion (dual diaphram) that it requires around 20 inches of vac to operate. Single diaphram take less! If this is true it might explain why I have never felt like the power upgrade did me much good. Still have to stand on the pedal for any quick stop.
By oldcarmark - 12 Years Ago
I have the 6 inch dual diaphram booster on mine and it works fine.There is a reserve built into the unit as most boosters do.Are you sure the brake is releasing all the way?You should have about 1/8-3/16 inch freeplay before the pushrod makes contact with the booster.You can check it with your hand without the engine running by slowly pushing down on the pedal.You will feel it when the booster piston  is contacted..Or you may have a defective booster.It takes very little pedal effort on mine.The dual diapragm is the equivalent of a much larger single unit. 
By Talkwrench - 12 Years Ago
You should get an easy 17" vacuum , My old girl still gets that. Ive not heard about them needing 20" to work, however I still have to stand on mine too, very bad fade, Also I need to put a mile or two with braking to "warm up" the brakes when I start out.  This may not be the booster totally at fault, Im thinking that it might be that the linings are not matching the drums well. Everything I have is new .. Got me ..?