4 wheel disc brakes. vacuum issues? - Pontiac GTO Forum
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post #1 of 5 (permalink) Old 11-05-2018, 07:48 PM Thread Starter
 
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4 wheel disc brakes. vacuum issues?

So I was thinking of installing four wheel disc brakes on my now all drum brake car. Thinking to myself that while the motor is out now would be much easier install. The question I have is will I have enough vacuum? I have a 67 gto original 400 and have installed a 068 cam. But without having the engine complete not sure what to expect. Opinions/comments appreciated.
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post #2 of 5 (permalink) Old 11-05-2018, 08:32 PM
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The 068 cam has an LSA of 116 which would provide enough idle vacuum for a power brake booster, you will see problems with vacuum and a rough idle when the LSA is below 112,

Randy


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post #3 of 5 (permalink) Old 11-06-2018, 07:05 AM
 
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I have a 65 with power front disc brakes and drums in rear. I have the 389 with 068 cam. No problems, almost 15" vacuum.
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post #4 of 5 (permalink) Old 11-06-2018, 12:29 PM
 
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I have ~ 11" of vacuum but the brakes work great with the booster (I have wired-up a vacuum pump but am not currently using it).

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #5 of 5 (permalink) Old 11-07-2018, 06:10 PM Thread Starter
 
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Thanks guys. I was looking at this kit on Ebay for $1200. I am sure There are better/more expensive kits out there but for mostly in town driving (3 speed manual/3:55 gears) It should serve me well.Drum brakes gotta go!
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Complete Engine Compartment Discussion

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