WarMachine

Recently I installed a Heads and Cam package on my LT1. I have a very low vaccum now. It reads about 12 on my gauge. Is this normally or is something wrong with my setup. The cam is a bit under the cc306, and the Heads are Race ports. I'm seriously thinking about trading this car in and buying an EVO if I can't fix this. I can't even have conversations in the car because the engine is so noisy now, and most of the time women are affraid to go for a ride in my car because it shakes at idle and the vibrations scare them. Either I'll return it to stock or sell it but I'm hoping fixing my vaccum problem might eliminate all of this somehow .

jay_lt4

stock cam = lots of vacuum

wild cam = no vacuum

i have a 383 with the cc 503 cam(also just a bit smaller than the 306 cam), and i have 14 in vacuum at idle, did you have your pcm tuned for the cam, timing and iac/ idle adjusted??

shoebox

Post the specs of the cam. An agressive cam is going to give lower vacuum and lope. I don't know how you could not have known this before install. Idle speed and timing can also affect the vacuum.

mrmint69

I was told the previous owner changed the cam but i have no idea if thats true. I think he said it to get more money and make the car sound like it was more than it was. Are there cams that are more aggressive than stock but sound and run similar to them? My vacuum is 16 but the car runs awesome and idles great now. My vacuum gauge and the Chilton says that 20-25 is the best place to be. I have been looking for leak that might explain the lower reading but maybe its the cam. Having no idea what type would make it hard to tune.

Injuneer

Have you checked the valve adjustment? Who did the tune? 12"Hg sounds low for a cam smaller than a CC306. As Shoebox indicated, post the cam specs. A narrow LSA will produce high overlap, and that will cause vacuum problems and rough idle.

matLT1

Thats the same vacuum I get with the cc 503 in my 355 also.