Author Topic: No brakes with large cam  (Read 931 times)

Offline turbo224

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No brakes with large cam
« on: June 08, 2015 - 11:32:48 AM »
I have finally been able to do a little test and tune with my cuda now that it's all put back together and the first issue I need to tackle is a brake issue. The brakes seem okay when I am driving at normal speeds, but when I am idling around at low speeds the brakes almost disappear. I currently have stock power disc brakes in the front and 11" rear drums. The 440 I am running has a very large cam, but unfortunately I am not positive exactly which cam it is. I suspect it's low vacuum that is causing my brake issue. I bought the motor from my dad who built it for a different project that he never got around to. He is trying to find the paperwork for the motor to confirm, but he knows that he had the machine shop put a cam in there with at least .5" of lift. I have not put a vacuum gauge on there yet to confirm which I know I need to do first before anything else. Assuming I have low vacuum, I have read a little about either a vacuum canister or possibly a vacuum pump? I have never dealt with this sort of thing, so I have no idea how any of that would work. Any suggestions for me?
~Tyler Larsen~Salt Lake City

-1971 Plymouth Cuda 440-6pk Tribute
-1992 Dodge Daytona IROC R/T




Offline RzeroB

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Re: No brakes with large cam
« Reply #1 on: June 08, 2015 - 02:37:48 PM »
As you suspect, it sounds like your cammed up 440 isn't creating enough vacuum at idle. Assuming that there is no other issue that is causing the low vacuum, you may need a "vacuum reservoir" like one of these sold by Summit

http://www.summitracing.com/parts/cca-5200?seid=srese1&gclid=Cj0KEQjw-tSrBRCk8bzDiO__gbwBEiQAk-D31Yo-PPwlrqUYSpY2jOYNAJxeA2r1mQiUjlgHUUyl94gaAjPb8P8HAQ
Cheers!
Tom
St Louis, MO

Former owner of 16 classic Mopars. "It is better to have owned (Mopars) and lost then to have never owned at all" (apologies to Alfred Lord Tennyson)

Offline Chryco Psycho

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Re: No brakes with large cam
« Reply #2 on: June 08, 2015 - 06:45:49 PM »
You could have a bad check valve or booster , the vacuum should be stored in the booster until needed , so even with the car off if you rock the check valve there should still be vacuum in there , if not you need a new valve or booster  .
 by far the best solution for engines with low vacuum running power brakes is Hydro boost , adapting a unit from an Astro van or similar & connecting it into the power steering pump provides far better braking with zero dependency on vacuum from the engine .

Challenger - You`ll wish You Hadn`t

Offline turbo224

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Re: No brakes with large cam
« Reply #3 on: June 08, 2015 - 06:59:52 PM »
Assuming I try out the vacuum canister, how exactly does this thing hook up? I see three different nipples on the canister?
~Tyler Larsen~Salt Lake City

-1971 Plymouth Cuda 440-6pk Tribute
-1992 Dodge Daytona IROC R/T