Brake Booster???

[6600DURAMAX]

Just finished installing new mild built 355 in my 72 and I believe my brake booster is bad. The cam is not that large,not for sure the size cause it was an old cam I had in another motor a while back, probably around a 282. Problem is it seems there is not enough vacumn and the engine wants to die when I come to a stop. Now I am going to install a vacumn canister, but I still believe the brake booster could be bad because the brakes have felt like crap for a while.

Now the main question, will a brake booster off of a 82 chevy 2wd pickup work??? Or do I need to find one of off a 71-72

thanks

[6600DURAMAX]

NO one knows????

[Shane65]

the brakes have felt like crap for a while

What brake pads are you using? They wouldn't happen to be the "better" semi-metallic or metallic ones? If this is the case then get some pads that are the non-metallic ones. Some parts places refer to them as the cheap sets. In reality they are the correct hardness for 67-72 trucks. The pads should be less then $20.00. The other pads are too hard and do a bad job of stopping the truck. I couldn't believe the difference in my truck. What vaccuum do you have at idle? Connect a vacuum pump to your brake booster to see if it holds vaccum. I wouldn't replace the booster unless it proves to be leaking.

[6600DURAMAX]

So, how exactly to you check to see if it is holding vacumm? I do have a vacumm gauge, so do I plug it into the vacumm hose off the booster and press on the brake pedal and hold it down and see if the vacumm bleeds off? Is this with the engine running??

Any help is great

Thanks Shane

[Shane65]

You need a hand held vacuum pump(like Mity-vac). The engine is off and the pump is connected to the vacuum port of the booster. pull 20" of vacuum and see if it will hold that vacuum. What manifold vacuum do you have at idle?

[72k5]

You can get a quick idea about your booster by simply disconnecting the booster and plugging the hose to the manifold. If the engine now idles well, the booster is leaking. You can often hear the booster hissing if it is leaking enough to cause the engine to die.

Another easy way to get an idea if the booster is leaking is to run the engine, driving the vehicle or simulating it by snapping the throttle shut from about 3,000 rpm a couple of times. Shut off the engine and wait 10 minutes. Apply the brake without starting the engine. If you still have power boost for the first couple of brake applications, the booster is not leaking. If you get no boost at all, either the booster is leaking or you have very serious vacuum problems with your engine.

I'm betting the booster is OK and you have other problems with your motor, esp. since you say it wants to die. More likely you have a vacuum leak at the intake, carburetion, or timing issues. Investigate these thoroughly, and get your engine running well before you replace the booster. Many things on these old trucks can cause the brakes to be less than impressive, and it would be a shame to waste good coin on something you don't need.

I don't know if the newer booster will work.

Good luck with it.

[6600DURAMAX]

Thanks guys, I think I know where to start looking now.

[franko72]

I checked my booster by turning off the motor and after five minutes I removed the vac. hose atthe check valve. I then slowly pryed out the check valve from the booster and heard the air hissing from the connection.meaning that it was holding vacuum.