low vacuum (hard brake pedal) Help!

[copteaser]

I installed a 218-218 cam in my engine, now the vacuum gauge only reads 9lbs. My brakes are hard as a rock. I am assuming that because of the large cam it can only generate very low vacuum. Therefore hardly any vacuum is getting to the master cylinder.
Any ideas on how to obtain more vacuum to run the power brake unit?

Thanks for any assistance

 

[cmokem]

Go to your local NAPA parts store and purchase the vaccuum pump for a early model sunbird. It works on a 12 volt system and pulls up to 18" of vac and shuts off. It automatically comes on at 12" of vac. Just hook the master cylinder to it and you should be fine. I guess GM had some problems with the 4 banger in the sunbird pulling enuff vac to work the brakes, but it prolly wasnt because of the cam selection

HTH's
Bob

 

[TurboBuickSix]

Good call

Originally posted by cmokem
Go to your local NAPA parts store and purchase the vaccuum pump for a early model sunbird. It works on a 12 volt system and pulls up to 18" of vac and shuts off. It automatically comes on at 12" of vac. Just hook the master cylinder to it and you should be fine. I guess GM had some problems with the 4 banger in the sunbird pulling enuff vac to work the brakes, but it prolly wasnt because of the cam selection

HTH's
Bob

Tip of the month for sure! Thanks for the info. Offhand do you know around how much $ they go for? Just to save some the time to call.

 

[copteaser]

BOB Yu DA MAN!
Maybe I can actually stop my car when the need arrives. I don't have stand on the brakes with both feet.

Thanks

 

[Nick Micale]

Originally posted by copteaser
I installed a 218-218 cam in my engine, now the vacuum gauge only reads 9lbs. My brakes are hard as a rock. I am assuming that because of the large cam it can only generate very low vacuum. Therefore hardly any vacuum is getting to the master cylinder.
Any ideas on how to obtain more vacuum to run the power brake unit?

Thanks for any assistance

Yes, find your vacuum leaks. We have 218 cams with vac brakes and they work fine.

 

[cmokem]

The unit I'm thinking about is a bit pricey..maybe in the $200.00 range...but if memory serves me correct..some Caddys with the 4-6-8 option also used a electric vac motor that has a bit more capacity. Maybe one could be had at the local bone yard for a good price.

HTH's

Bob

 

[Roger]

PM doesn't use vacuum.
I've tried vacuum & went back to PM - $199 at Discount Auto Parts.

 

[John Larkin]

Does it matter if the brake booster has "X" in/Hg of vacuum or does it just need vacuum period? If it just needs vacuum, then a new check valve should fix it. What source are you getting your vacuum from for the booster?

 

[cmokem]

From what I recall vac is increased in multiples of hydraulic force to operate the brakes...the more vac you have the more force you can apply on the brakes... Ideally a vac of 12-15" is ideal from what I read..but I could be wrong about this. Anyone else have thoughts on this

Bob

 

[TurboBuickSix]

I also remember hearing from somewhere that all boosters were not created equal for a given model.I had a 70 LT1 Z28 with PB was told it was a special booster because of the low vac in the LT1? There are after market companies that sell new boosters as well.You should try to put a hand vacuum tester on the booster and see if it leaks and you can also add more vac than you are getting from ther motor to see if the feel improves.