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Hello,

I have a problem and a little baffled. My brake pedal on my 1972 MC Custom are very stiff. Just putting the car in drive and then pushing the brakes barely stop the car. Back wheels still turn when up on a lift and pushing the pedal. Very stiff pedal and hardly moves. Have replaced both Master Cylinder and brake booster but still  have the same issue.  454 big block original and AC car. Any thoughts? Could a vacuum canister or vacuum pump be added or help? The hoses are new and it has a Edellbrock 650 carb.

Any suggestions would be of great help. I want to be able to drive my car!!

Thanks. Jeff

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Silly question....1- Do you have the vacuum hose hooked up to the booster? Make sure it's plugged in. (Ask me how I know) lolol

2- do you have the brake booster attached to the brake pedal in the correct location? 

3- is the rod between the booster and master the correct length? 

4- how much vacuum is your engine actually making? With a 650 carb I would think the engine is not that radical warranting a vacuum can or a pump. What are the specs? Correct timing? 

Hope this helps...

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Thanks. I have done all of the above except for adding a vacuum can or pump.

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Engine is stock, no bigger camshaft? (you said 'original', but you know how that goes).

Has it always been this way?

And like Tom asked, what is the vacuum reading?  The hose is connected directly to the intake manifold port and not someplace on the carb?

Headers, especially if they're real close to the frame mounted proportioning valve?

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Tom and Joe nailed it, get a vacuum reading.

A single diaphragm brake booster needs at least 16 inches.

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