Low vacuum with brakes

[mobileaudio25]

i did a top end on my motor and ever since the bigger cam lowered my vacuum tremendously. I bought an air canister which helped but still not even close to safe.

I did the blazer brake upgrade with drilled and slotted rotors, breaking improved a little bit more but no way is it near its full potential.

I have the smallest brake booster ever put on our gbodys. Would going with a bbody caprice booster or a dual diapham Monte Carlo booster which is a lot bigger help my problem or no because the vacuum isn't there in the first place? Few more bugs to work out....

 

[foxtrot]

What does your current vacuum measure? How much lift does your cam have?

You could always run one of those vacuum pump kits to be safe..

 

[timo22]

Some GBodys came with diesels and those cars used a hydraulic boost for the brakes. Good luck finding that set up. I don't think many were made. Astro vans come with hydro boost . I've heard of guys using them on their cars. I'm sure Google would give you some info...timo22

 

[Texas82GP]

If it is a matter of not enough vacuum for the booster, check out the pully driven vacuum pump setup 565BBC is running on his beast. It looks very reliable.

 

[mobileaudio25]

Yeah jegs makes an electronic vacuum pump for $200 that always keeps the vacuum around 18. I'm pretty sure that would solve my problem 100% I'm just looking to an alternative to a $200 fix. I'm currently measuring between 8-10.

 

[Kwik_Cutty88]

I have a hella UP28 (iirc) plumbed into my vacuum system. I use an SSBC vacuum switch wired to the brake pedal so it only comes on when vacuum drops below 18" and my foot is on the brake pedal. I also have a vacuum can. You can find a lot of the hella pumps (UP28/UP30) on late model GM cars. They used them as supplimental vacuum pumps as well. IIRC I think I got mine from a pontiac G8. You might have some luck at your local junkyard for way less than $200. My motor only makes like 7-9" IIRC and it helped tremendously. I can actually get the car to stop with much improved pedal feel.

 

[Injectedcutty]

If I were you I would definitely add a vacuum pump. I had the same issue and dealt with crappy brakes due to the healthy cam my 355 had. Once my resto began I vowed to add a pump and it made a world of difference for the little I got to test it out. Mine is a CVR brand, but has summits name on it which made it a few bucks cheaper. No its not the cheapest option, but it made the car stop as good if not better than my 07 Mazda 6 daily.

 

[mobileaudio25]

If I were you I would definitely add a vacuum pump. I had the same issue and dealt with crappy brakes due to the healthy cam my 355 had. Once my resto began I vowed to add a pump and it made a world of difference for the little I got to test it out. Mine is a CVR brand, but has summits name on it which made it a few bucks cheaper. No its not the cheapest option, but it made the car stop as good if not better than my 07 Mazda 6 daily.View attachment 56528

Were you running factory break setup or did you have some upgraded braking? Also I have the smallest power booster made do you think if I were to stick with the small booster and get a vacuum pump I should be ok?

 

[Injectedcutty]

Were you running factory break setup or did you have some upgraded braking? Also I have the smallest power booster made do you think if I were to stick with the small booster and get a vacuum pump I should be ok?

Yes, I was running the factory setup but my 87 cutlass had the larger booster. I added a vacuum can at one point but I really didn't notice any difference to be honest. I still have factory size fronts but with drilled/slotted rotors and drums in the rear. However, I do have all new stainless brake lines front to rear, and stainless flex lines with the addition of the pump. The unit I have was pricey, but the solenoid, switch, etc is contained into the unit preventing clutter. I have it on a 30 amp toggle switch, but it shuts itself off once 22 inches of vacuum is reached. If it goes below 18 it will kick back on.
I think the small booster might suffice, it just can't obviously hold the volume that the larger booster can (btw my stock unit is for sell). A pump will definitely improve braking though, as larger cam and less lobe separation profiles rob vacuum the engine doesn't have the necessary time to build vacuum.

 

[mobileaudio25]

Yes, I was running the factory setup but my 87 cutlass had the larger booster. I added a vacuum can at one point but I really didn't notice any difference to be honest. I still have factory size fronts but with drilled/slotted rotors and drums in the rear. However, I do have all new stainless brake lines front to rear, and stainless flex lines with the addition of the pump. The unit I have was pricey, but the solenoid, switch, etc is contained into the unit preventing clutter. I have it on a 30 amp toggle switch, but it shuts itself off once 22 inches of vacuum is reached. If it goes below 18 it will kick back on.
I think the small booster might suffice, it just can't obviously hold the volume that the larger booster can (btw my stock unit is for sell). A pump will definitely improve braking though, as larger cam and less lobe separation profiles rob vacuum the engine doesn't have the necessary time to build vacuum.

Are you upgrading to a new brake booster? How much are you asking for it and it's the original booster that came with the car right?