power brake vacuum

[gunmetal72]

I just put in a different cam into my 340 and it seems to have affected the power brakes. They work but I have to push harder and seems they take longer to build up enough vacuum. Is there any thing I can do to get more vacuum to the brake booster? I thought about adding a vacuum reservoir, but before I did that I thought I would ask in case anyone has had the same problem. I may not be on the right track,not sure

 

[6.1cuda68]

Im thinking the cam has reduced the amout of vacuum you have and the booster doesnt get the nessasary assist it is designed for. Typically vacuum needs to be in the 15 inch range. A quick fix might be to try a smaller bore master cylinder. A manual brake Master should have a bore size of 15/16, the power one may be larger than that.

Just pull the master off the booster but still leaving the lines attached and measure the bore, if its an inch or bigger you might want to try a smaller bore size. the only draw back you might experience is slightly more travel on the pedal to achieve the same braking effect.

Another alternative that you mentioned is a canister and/or adding a vacuum pump. I'd try the smaller bore master first. Hope this helps. Marcel

 

[68383GTS]

vacuum canister

 

[1968FormulaS340]

Ditch the power assist. We have manual discs on both my Barracuda and the wife's 73 dart.

They work awesome.