I just hooked up a vacuum gauge to see how much vacuum I am pulling with the CC306 and ported heads. When I start the car up, the gauge goes to about 12 in. Hg. After about 15 seconds, it drops down to 8-9 in. Hg. When I put it in gear and am sitting still, I'm getting around 5-7 in. Hg (usually right around 6).

I was just wondering how much vacuum everyone was pulling with a similar setup. I've searched some, but most people who say they're having issues with vacuum don't tell actual numbers. In this post, jcobz28 said that his buddy had 10-12" of vacuum. My brakes aren't where they should be in terms of braking power (at least in my opinion). Am I just looking at normal vacuum numbers for my combination and just have to deal with it?

 

Umm all i know is my brakes work fine..

 

I am having the problem with my brakes after my cc306 went in.

What i have been told is to get a one way release valve or something like that in the boster line, that will keep the built up vacum in the brake boster.

I noticed that if i rev the car up a lil the brakes work better, maybe we have a vacum leak?

I hope some ppl do chime in on what vacume they have with the cc306

 

Anyone with the cc306 and a vacum tester?

 

Put your idle to 900rpm, or 1000(might be a little high) if you have a stick(for other guys reading this).
Vacuum is around 11 for my 230/236 cam with 396.

 

Yeah, mine idles about 900 rpm (automatic). I just put in a vacuum canister yesterday, and it made a lot of difference. 97formula1234, you might want to try one. They're only like $45 from Summit. I still feel like I'm not getting as much vacuum as I should, though.

 

My breaks work fine.

 

Good...now back to my question, what vacuum numbers are you pulling?

 

Physics, after the vacum canister are your brakes fine now,

kinda confused because u said you thought you still wernt getting enuf vacum. Did u mean in genal u wernt or with the brakes and the canister their still wasnt enuf vacum for the brakes.

How/what does the canister do?

 

my brakes, always werent the best either..but I dont have any #'s for ya either..

 

TTT still looking for some vacume numbers of a car with the cc306 cam to compair to mine.

 

8-9 in. sounds really low. Sounds like thier is a small vacuum leak somewhere. I have never vacuum tested mine but my brakes were just fine with the cc306. If a vacuum canister doesn't fix it, you have other issues besides the cam, trace down that vacuum leak.

 

Just my 2 cents worth, if the vaccum is low try this, are the liftes adjusted correctly (ie Comp R's 1/16 turn past zero = .002-.004 pre load), and what are your counts on the IAC. A reputeable tuner on here is haveing me adjust mine to where it is at around 30 counts once warmed up. My vacuum is not as low as yours, but I do have a XE 230/236 cam and I am around 12HG vacuum.

 

By design, brake boosters will hold a certain about of vaccuum even after the vaccuum goes away. Usually you will get 3 pumps if you don't have vaccuum anymore before the booster looses it's "saved" vaccuum. They do this so that if your car dies you still have power brake, atleast for 3 pumps. A check valve will not do anything more than the booster is already doing.

As for vaccuum numbers, I wish I could help, because if i could, that would mean I have a cam, and I don't yet

 

mine is about 12 to 13 inches at idle maybe you have a vaccum leak some where?