I installed a 406 with a large cam XE284, I have heard that a large cam can hurt vacum.. Whats the fix and how much will it cost me?

 

do you have a vacuum gauge? whats the vaccume at idle?

if its low you need an reserve vacuum canister
something like this one
http://www.jegs.com/i/JEGS/555/63010/10002/-1
you can get aluminum too.

personally i dont feel that your cam is large enough to cause this issue.

 

I had the same issue when I swapped in my 350. I found that if I adjusted my timing up slightly, and lowered my idle at the carb to compensate, it helped my vacuum just enough to give me alot better braking. But I can't explain why - maybe a seriously technical guru can chime in and provide some deep insight as to why this worked

 

Does my idle speed work for that car? I believe I had mine set to around 950-1000 rpm and i gave it a good bit of timing at idle to help stabilize my cam. Timing and higher idle do help the vacuum issue but theres only so much it will help. I'd keep playing with the tune for now to see if you cant get it to work out without a canister. Verify idle speed/IAC counts and engine timing along with air fuel ratio. Work those abit to see what the car likes. If the brakes still suck, then should look into a vacuum reserve canister. I forget how much they cost, but my 383 didnt have brake problems and i had a pretty aggressive cam.

 

more work and $$$ but hydroboost is an option too. then you could add a huge cam and not worry about your brakes.