I have a 65 velle with a 454, stock 281 heads 10.5:1 hypereutectic, performer RPM intake, holley 850 double pumper.

The cam specs are as follows: Comp cams part #11-213-3

view the specs here: http://www.compcams.com/Technical/CurrentCatalog/HTML/172-195.asp

.550 gross valve lift
244 duration @.050
110 lobe separation

I converted to a power disc setup a while back. My brake pedal has always been very very stiff and the car never stopped well. Well today I found out why. I just bought a vacuum gauge and I am only pulling 10" of vacuum at idle (900 rpm).

Does this sound normal? If so, what is my best option to do? Should I ditch the power and go manual setup? Should I get a vacuum pump (if so, what kind)?

Help!

Joe

I just read this thread: http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=7;t=005858 about a vacuum check valve. I am sort of confused about this. Is the check valve the plastic nipple coming out of the front of the booster, or is that thread referring to another valve placed in-line with the vacuum hose running from the manifold to the booster? Right now I have the hose running from the bottom of the carb right to the plastic nipple on the booster.

Go to your local parts store and their "HELP" section. You should find the check valve you are looking for. Looks like a big black fuel filter. usually straight through but I've seen some with a 90 on one end. Put that in and It should be better but I think 10" is still a little low for power brakes.

Jeff

10" is about right for that combo, maybe could get a little more with tuning, anything less than 13-15" is gonna make power brakes a little tough. The check valve is the plastic peice on the booster that the vaccum line attaches to-pretty easy to check it either works or it doesn't.

Here's another data point. I have 2 vacuum sources being used on the motor. The brake booster is connected to the back of the carb, and the passenger side breather is connected to the intake manifold right behind the carb. When I took the vacuum reading I used the hose from the back of the carb, and left the hose to the breather still hooked up. I then capped the hose running to the breather (sealed it), and re-ran the test. To my amazement it was the same 10" of vacuum! Wouldn't you think that plugging that hose would raise the vacuum by at least a few inches? Am I going crazy? None of the hose connections were leaking as far as I could tell.


Joe